Episode 104 - What’s Really Holding Up Your Building?

The Structural Engineering Podcast. Action. Well Max, pretty excited about this one. Talking about foundations. Pretty, you know, common thing, one might say it's foundational of what we do. Structural engineers, but I think this is be a lot of fun. You know, one of our listeners wrote in and wanted to do this episode for us to do this. And I think it's a great idea. We'll dive into actual foundation systems here in a little bit. But I thought the most natural place to start truly was with the geotech. How do us as structural engineers interface with the geotech? Where's the importance, the liability, you know, things like that? What liability and risk might we be taking on by not following the report or things of that nature? So I want to start off asking you a question Max. Why do foundations matter? You know, it's going to be hard. A lot of these foundational topics, they have a lot of jokes that can be tied to them. And it's very the baseline of our career to make a joke about the foundation. Anyway, what was the question you asked again? I mean, they support the building. I think any good answer is going to be sound like a joke. They're the baseline of our structure. They keep it literally stable. Baring quality is against the soil that we have, whether it's expansive, weak, collapsible, or excellent. It is how we brace our structures against the earth. Yeah, something I was thinking about too is like a common misconception about foundations is just that they're standard and they're kind of an afterthought. You know, it's like, yeah, we'll just kind of figure out the building we're going to hyper focus on and we'll find some foundations that kind of work. But you know, one of the, they're the first thought. Yeah, one of the things I found was that out of our whole industry, one of the highest limits of insurance and cost is geotechnical. And it makes to me a lot of sense because it is so unknown. It's something we can't see. And you think about it, they're boring holes in the ground periodically, hoping that things stay pretty consistent. There's a whole profession behind this. So you'd have to imagine they've gotten pretty good at this. But there's many lawsuits that are huge that over the years I've been in structure mag or something similar that talk about foundation challenges. Usually it's when a design team or a geotech or an owner decide to kind of get it a little exotic, let's say, and not go with the tried and true foundation types that we utilize or similar systems or depths that are in the region. So find that, you know, it's such an important piece of what we're doing. Yeah, I often think that, you know, the geotech has approximately five points of information on a site, right? They might drill five boring holes to paint the picture of this entire site. They could miss a pocket of soil that is that will be a problem and they have to assume this entire picture based on five key points. And they often do a great job. I mean, not on them. They do good. But, you know, they can often paint a very accurate picture. But if they can't see a geologic feature of the ground that is hiding some poor soils or maybe there is a like a bedrock dropping off point and they aren't aware of this, we can have weaker soils over this and it just changes the whole picture. But it's not in the picture that they drill. Yeah, I think about it as like the LRFD overlapping bell curves, right? You've got one for load. What is our statistical chance? We assume the load was, you know, correct. And then the other bell curve is strength. And you know, that overlap is the failure, right? It's not strong enough and the load is too high. And I think of like, when we design, we feel so confident that our load is right and our strength is right and that failure mechanism is so small. But there's so much testing and data that we can do. And ASTMs etc for grade that feel like that's a really small piece of chunk of failing. But when you get to soil, could you imagine that they test one beam out of the whole building for the strength of it and we just use that blindly? But I feel like that's almost what they're doing with the soil. There's so many tons of earth below this site and man, like, I wonder what those overlaps more look like when you, you know, start talking about the technical standpoint. I want to actually dive into what the variability they have. But think about like our wide flange beams that are 50 KSI. Like that could be 55 to 49. I'll double check those numbers, but you know, it's a pretty small window leaning stronger. All right, I'm not a statistician, but I can tell you that A572, grade 50, frequently exhibits higher than the nominal strength that we use. Typically, we're seeing 53 to 60 KSI, depending on the producer and the heat used. There's some dynamic effects they want to come forth thickness effects as well. It's a safely larger number. I have a feeling the window that geotext would look at is a big window. Yeah, absolutely. I think it makes sense when they, you know, factor up or down values. I can only imagine, you know, before they set out their report, they're saying they're like, that one boring didn't look great. So let's increase that safety a little bit more. I think it'd be really fun, Max, in a future episode to have a geotech on because I have some reactions. I really enjoy talking to geotech engineers. There's so much to learn from. So, anyways, that's for a future topic. So the first thing I want to start off with is asking you, what do you typically provide from the structural engineering perspective? What do you provide to the geotechnical engineer for their analysis and what they need to do? I'm generally giving point loads and slab loads. And usually early in the design, this is an assumption, but we try to be within 20, 10 percent. And that's reasonable. So, you know, building size, use as if that's exactly needed, but if they could just have the weights, that's everything that they're going against. And then, you know, exterior items like parking, roadways, they're going to need to know that it's not exactly important to the building, but that is what I would be sure to give them. That match will you're thinking? Yeah, and a few other things that I've personally come across. Usually, they're asking me for the column loads and wall loads, which you'd mention. Then they're asking for a minimum number of borings, which I find intriguing sometimes that geotech might ask the structural engineer of that. But there's some good rules of thumb for that for both how big the building is in plan, as well as how tall it might be. And is there a little codified, this number I had in my head of a five, borings in a medium sized site that is based on reading something a long time ago, but is there a codified this many borings per this many square foot? Not directly that I could find, but some information I found. So, the other thing sometimes to provide is the minimum spacing between boring. So, something I found was for a one story building, two to six, borings, and anywhere from 75 to 200 foot kind of on center from the spacing standpoint. Up to three stories, you want, yeah, over four and 50 to 150 foot spacing, so kind of still similar. And then when you're getting to the high rise, you want a lot tighter spacing. So, 25 to 50 and then more than six. And so, where I thought it was interesting was, you know, it doesn't that guidance didn't really fully speak to the plan area of the it's this book of the height. What I would be interested to know more from a geotech and like people that an engineer said design high rises like really tall buildings is how deep do you feel you should go because you know the idea with the depth of the boring to my understanding is at what point does the ground feel no more load, right? The soil it's going to dissipate all your building loads. So, if you didn't have to a point. So, if your building is 500 feet tall, I would imagine you're not boring also 500 feet deep, right? So, it'd be interesting to see that correlation. Not something I looked up or found for this discussion, but some, you know, something to think about. So, yeah, I actually also I'm picturing about this as when is the building weight a minor percentage of the total soil weight. So, once you're 20 feet down, you have 20 feet of soil over you, the building weight is a fraction, I in most cases, in a small structure, building weight is a fraction of that 20 feet of soil, but, you know, right, is that sort of a component of that distribution? Let's take a generic building weight where there's going to call it 200 pounds per square foot. Maybe this is a three-story wood building, a two-story steel building. Maybe it's a very heavy concrete building, only one-story. Anyway, the graph here is pretty asymptotic. So, as we go down, we are a high percentage of the total weight for a while. Once we're down to, let me look here, 35 feet, we're only 5% of the total weight. And as I to say it's asymptotic, it decreases pretty slow at this point. To get down to, let's say, 2%, we have to be 75 foot deep. This gives us an idea of the scale of the building weight to the total soil weight accumulated. You know better than anyone. 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And then once you potentially hit refusal, right, you hit bedrock, just every site all over the country, all over the world, just so drastically different. But other things to consider providing a geotech would be preliminary foundation types. You're considering where you, depending where you're at in the design and thoughts of you've worked in the area, like you said, blueprint or column layout, if there's basement levels. One that's really important for everything we do is anticipated tolerable settlement. Geotechs have a good rules of thumb they utilize and they usually provide you. But if you have some sort of something that's special with what you're doing, the tolerances could be good to provide them or to tell them like this building can see typical movement or the owners okay with a little extra or a little little because it really just comes to cost. A building doesn't, something I learned earlier in my career, like a building doesn't fall through the earth, right? If you add a lot of load, it's not going to just completely go through the whole planet. It's all settlement based. That is the short term and the long term settlement. And so that's what they're juggling the whole time. Many times in their design and something we'll talk about with shallow foundations, that's a big piece of that versus our deep foundations. Yeah, I think something that's big about settlement, think about originally is a fancier foundation that maybe gives us a higher bearing value, but maybe you have to drill into earth to get that. That's often settlement tied. And so when a developer is more tolerant of a little more settlement, they're basically saying, what's a cheaper foundation that like if it can work within sort of code requirements and what we just think of as standard for a building, that's what I want. I want this building to be safe and usable, but I don't exactly care if it doesn't settle an eighth of an inch, you know, different, different characteristics. Yeah, I've always found that. This discussion could go on further and maybe come to ethics and a lot of other things. I always find it interesting when the owner is willing to assume more risk of movement, then that owner may also sell the building within a year or two and guess who's still liable for the building and that's us. And so I always find as like in our AEC world is like certain things that, you know, we should take risk on or push the bounds a little bit more like maybe you'd be okay with something deflecting a little bit more, but when it comes to the foundations, I've always thought like to go in and retrofit foundations is one of the hardest things, right? You're beamed deflects, well, the steel plate to the bottom, add another joy, sistered up, you know, probably some reasonable ways, add some carbon fiber, you know, something with concrete, but when it comes to foundations, man, if you got settlement and bad issues, you got to lift your whole building up or you know, you got to do something that slows it down like what a challenge. I always don't know until it's a real issue like if that your foundation has cracked and you can't see it underground. Not till all the repart is corroded away and this thing really moves, do you know it? Yeah. So my suggestion would just be to document any decisions that are made that way for future use. Yeah. If the owner says, hey, I'm good with like three, four inches of movement, make that foundation as cheap as possible. You know, maybe that's not the right answer. The buildings, you know, I don't know, there's different opportunities, but I think something we just always got to remember is like we, we own this building for quite a while as a design professional and that owner can just sell it tomorrow and doesn't necessarily, to my knowledge required to disclose that information that the foundations are designed to let the building move a ton and it might take a while for that building to actually move. So I don't know, something I always find interesting. So Max, what would you expect to get back from the geotech? What's in the report? What are you looking for? I'd like a little engineering stamp at the end in a signature that's saying we believe this information. I'm looking mostly, these reports can be pretty long and early in the career, I would just flip through and definitely look for the key points. Now I'll look a little deeper, but still the ultimate takeaway is what is the bearing value, the little deeper here is like the confidence in what they found in this soil. So they'll give in the summary what the outcome is with the bearing qualities are, but they'll give you a little more detail in the reports. Consolidation that they would expect, bearing values for things that a structural engineer needs to use, bearing values, there's truly only one. If you're just helping out on a project and you need another bearing, control F, search the PS, search for PSF and that's basically the answer that you will need. What am I missing, Zach? You got the big one, a lot of well bearing pressure, foundation options. So often they won't just say, hey, shallow foundations, they might say, you could do shallow, it might move three inches. We would recommend deep foundations or these three different options of deep foundations. So usually there's some recommendations. If it's pretty straightforward and obvious, it's usually just one. And I find useful is looking through the boring, finding groundwater levels because that could affect construction of things in buoyancy. Do anything underground. Boiancy is a pretty big deal and a huge load. I mean, this can be substantial. General soil conditions, again, reviewing the boring, swell potential. That could dictate your slab. That could dictate, yeah, you do have a structural slab depending on your swell potential as well as your foundation's system deep versus shallow. Values for your retaining wall at rest, pressures, things like that. Potentially site specific things for seismic. It'll give you your site class and some of your seismic parameters. It would be, you know, it's a good place. Maybe some information on settlement, total versus differential settlement. Those are both two numbers that are important to look at. And lateral soil parameters, both for the whole building. How are we going to resist this sliding per se during a winter seismic event? Subgrade modulus can be pretty important. When we talk about deep foundations, skin friction and end bearing. Sometimes there's a minimum dead load if your swell potential is a little bit higher that you may need to provide for your foundations. Work with action potentials and high seismic and some construction considerations and limitations. Depending on what kind of soil you have, there might be different requirements for how they're going to build it. And, you know, I think that's sometimes when you get into the existing buildings and you have to kind of excavate down a little further than the existing foundations, it's pretty important to know what's under those existing foundations on how the soil will act. When you do that, I wouldn't say you should undermine the whole foundation, but in certain sections, it's good to know that. What sort of differential settlements do you think is commonly acceptable? Or what have you seen in a report and you say, that's more than expected, but that is still okay? I think something that I've commonly found is kind of this one inch of movement in total and then a half inch of differential. It seems to be common to what I've found. It will vary for sure, maybe an inch and a half. I ran into where, you know, geotechs are very specific on what they're comfortable with, which I love. A confident geotech is like, "Hey, this is going to settle an inch and a quarter. That doesn't make me comfortable. We're going to lower the bearing value. We're going to do one inch." You know, it's, yeah. Those scale of questions. I have looked many times, and if any of our listeners know, please email us. I've looked up recommendations for total building deflection as well as differential. To me, the total deflection isn't as big of a deal. You might have issues with exterior doors that go out. The newer IBCs require structural stupes for exits, so that kind of hopefully should solve that challenge. But to me, it's the differential architectural finishes. You don't have to be a lot to really start affecting the structure. But, you know, if you talked about a pre-engineer-metal building or, you know, let's say a steel building in general, I'd feel more comfortable with a little more flexibility than I would with a pre-cast or a tilt or a concrete building. You know, just from a strain standpoint, there's a lot more flexibility, let's say, in a steel building, maybe then a concrete one, you might think. If you're to say the building differentiated. three inches. That could be substantial, maybe even for both. So I kind of like that half inch or three quarter inch and one inch, let's say, is something that's maybe more common to see. Yeah. I want to throw in a little structural trivia topic for you here, quick like the Millennium Tower. We've talked about this one, but as far as settlement goes, I think it's eight inches, 18 inches total settlement. There's a lot of other items going on here, but for the scale of what can occur, it can't get that bad. But yeah, I agree on the half inch differential settlement being the most common one that I have seen. And I actually did a, oh, when I was learning about engineering software, I played around with what sort of force can you put in a brace frame when you force one foundation to settle a half inch over a 25 foot span, just like my interest of how the building is placed together and where house stresses are developed and what additional force you can put on a foundation because of differential settlement. And I don't remember my takeaway from this. This was 15 years ago, at least half inches of the number I used. Yeah. And going back to the building in California that settled 18 inches, if I remember correctly, instead of doing, and I'm going to be probably off on these numbers, but from a relative standpoint, instead of drilling the case on 300 feet down to good soil, they drilled them like 100 or 150 feet down in kind of this marsher or mud, more or less that they have in the Bay Area, I believe is where this is. And that like they thought that there was something they could do with pouring more of them, but shallower, something like that. And it's like, man, now looking back at that risk, I'm sure not a single person on that team thought that was a good idea in hindsight. And I think it's a good reminder of just our whole industry. And you know, there's times to take risk. And I bet they it was calculated that was a really good idea. And now, man, 10 years later, something like that, it's still a challenge. They're still trying to figure out a fix it. There's great articles on it. If you'd like to learn more, I find it fascinating. You never want to engineer something and it creates a problem. But it is fascinating on how engineers solve problems have been created. Like how do you stabilize or lift up even that edge of the building that's settling 18 inches? I mean, that's incredible. Okay. So let's go back big picture. What drives your foundation selection? What do you say? What's your initial thoughts there? Initial thoughts, the building type and the region and the typical foundations used. Right. So if you've done work in some area, you probably know that the two story buildings are all in shallow foundations. I wish I had a number of this, but I bet you 95% of buildings are on shallow foundations or maybe higher. That is really common being aware of what is in the area is super important. But that is usually my starting point is. And frankly, most of our buildings are medium to small and they're houses are commercial and they're on a standard foundation. Unless we've got soil that is clearly should be inspected by a geotech. Some other things I was thinking like from an impoliminary standpoint is what is the structural loading at some point? You might run into a challenge with that. The soil conditions, the variability, the compressibility, the strength, where it is groundwater to live. That plays a big role in some of the systems that we're going to talk about. Scysemic considerations, how the foundations act during an under seismic loading, frost depth. So that's a big thing across the whole country. You could have 54 inches of frost depth or you could maybe have 12. It's a big deal or man, something really cool podcasts up so we could do is talk about permafrost. How do you build in permafrost? Like what? I mean, the more north you go, I mean, it just becomes a huge challenge. Adjacent structures and utilities could be a big deal. Do you have a zero lot line? How you make a decision on the foundation system and then construction considerations, schedule, access budget, et cetera. I think play a big kind of initial role in how you I feel like I'm curious for you Max, when you get a building, let's say a client calls you and says, Hey, I got this three story, precast building in this area that you've worked in a ton. You start thinking what that foundation is going to be, right? Before you get a geotech, you got a preliminary idea. Absolutely. And then I will just double down and say that the geotech information, you might have a good idea what that foundation is going to be. But if it's a commercial structure, I would not produce something without a geotech report that residential is very often without a geotech. And that can make sense, especially in a neighborhood houses are dense. You know what it's likely to be. But if you're building a new house on the edge of a lake, I would probably want a geotech on that because you have high groundwater. Definitely. Like you can see where it is. So there's some other consideration. Yes. We generally start with a good idea what it will be. But we want to fall back on the geotech report for what they're expecting to. Yeah. I think of a lot of within the world we live in as risk. Everything we do has a level of risk to it. And you know, if you, as you mentioned, maybe you have a residential house, it's going to be very light. If you're caught if construction, you know, and the way things are done in that area are very consistent, you know, maybe doing presumptive values from the IBC and using 1500 PSF, let's say unless you know different of the soil conditions. You know, I think it would be acceptable. And then where you're shifting risk is maybe you put in your drawings for the contractor to verify with a geotech, the soil type and foundations, and conditions when they're in construction. The challenge with that is, if you wait till then to get that verified, you could have to redesign the owner of what might have costs that they weren't aware of. The presumptive soil values, I think, can be good early on, especially if you're very aware of the area. But most, if not all of our construction or commercial projects, at least that I've been on, I would say majority of them have a geotech. I think in the residential side, actually, I thought the bearing value presumptive was an IRC table. I didn't, is that IBC does allow? Okay, yeah, IRC does also have this table and it's 1500 is the, who won't say the lowest, but I thought it was. But yeah, you know, between 1500 and 12,000 something like that. I get a number for you. We are at 1500 clay, sandy, silty clay, clay, silt and sandy silt clay. And then we're going up to 2000 with sand, silt, the sand. Wow, there's a lot of repetition here. Play, sand, 3000. We might be doing sandy gravel, sedimentary rock that's going up to 4000. If you find crystalline bedrock, you're doing 12,000. This is out of the IRC. These are just presumptive values that you can use in your head, what you might expect from the geotech. In the residential side, you also have an open hole inspection, which is, I know nothing about it, so I can't speak on, but it's basically, unfortunately, instructional engineer or hopefully a geotechnal engineer going to look at the soil and see if it looks like a big pile of clay, an old landfill or nice, aggregate and not that much organic. I think summarized like what drives it? It's a big, important piece to this is it's so rarely it's just a structural engineer. There's the contractor. There's underground utilities that MEP is bringing in. There can be a lot more pieces, the geotech, engineer, etc. That comes into picking the foundation system and is not just us saying, hey, this is what we're doing now. So any commercial structure type that you would feel confident designing without a geotech important? In go full scale here, but what would you, you know, what would you confidently put a stamp on? That is with with the caveat that it will be checked during construction or it will never be checked. It'll be checked during construction. Hey, I want to say this is a conceptual question. Yeah, I would say unless you're building a shed, get a geotech, no report. It uses better words than that, but I'm just curious, where do you feel the most comfortable? There are minor things. If you know the soil in the area, it's a minor structure. You can get away with that geotech report, but I am really against it in big picture, but just curious, would Zach's thoughts are here in general? Let's say probably a, like a, maybe a, man, that's a great question. Maybe a one story steel, lighter, you know, one story would, two story would probably wouldn't be a huge deal because if they found it was maybe a thousand and not 1500, which would, could be a while, you could make your footings a little bit bigger and it would still be okay. From like a, I don't know, substantial loading. One story, steel building probably or metal, pre-engine, metal building. I would think as we get into heavier structures, pre-casts, cast and place concrete tilt and multi-stories of those, I wouldn't feel as confident, I think, and just assuming that. Because of just the rest, like the movement factor, like 50%. 1800, you know, we get a value from a geotech that is purely tied almost purely I shouldn't say that, but majority of the time tied to deflections and those requirements. So I think that's the hard part is as you get to these heavier buildings, the soil is going to want to move that, you know, short-term and long-term movement. And depending what soil can types you have, that can vary. So I know lighter buildings, I think, and an important thing to me is that we as structural engineers aren't making the decision in a vacuum and that we're making a decision on taking risks as a team. So Mr. Owner, you don't want to get a geotech report, you can understand that building smaller, lighter areas, pretty consistent soils, we'll need to get and you know, have a geotech come out there during construction and verify our assumed values. So you might take the risk on then, but I think one of the things that as an industry we do without with thinking we're doing the best thing is not involving everyone in the decision making. Like why do we think it's our decision to tell everyone like this is what you're going to do, but not tell everyone the risk at the like later on like, hey, you might dig this up and find that nothing we thought would work. Like that's a huge risk and maybe the owner and the contractor, no one wants to take it or if you're hired by the architect, you might make them look bad, litigation, all those things. So I think it's an important that we're communicating. We're talking about the risks that sit with these things and it lowers our risk. Like hey, Mr. Owner, are you willing to accept the risk of figuring this out later or architect? Are you, you know, but I often think, you know, it's not something we should figure out, consider. I don't know. I heard this once and I really like this and this is sat with me is if you know, if we don't care what the value is, even even our building deflection comment, one inch or half inch differential, at what limit does that affect us? At what point do we actually care that will drastically affect the building? Often the limit that we probably would drive towards is bigger than what the finishes could account for what the building owner is okay with. So so often those aren't just our decisions to make. It's, it is a point of discussion to have with everyone. So I think if you come across a question and you're unsure of what the answer is and you're like, I don't really mind what it is. This goes more than just geotax. It's probably because it's not your decision to make. You know, if, if, when it comes like steel beams, like we need this, we have to have this beam. You know, like it, that is important to us, but there's, there's so many decisions that we make that aren't just us to make. So going off on a tangent. I like to think, no, no, sorry. Let me, let me tie the tie the end of that tangent is, I think in a lot of industries, well, we think of ourselves as paid to be paid to give the answers. We are paid to be the expert and we ask questions to people knowing what the breadth of the answer is, but we are not paid to give the deflection needs to be this. We're paid to respond to what our thoughts on what the deflection should be. Why this or that? What is cheaper and more effective, but we're not paid to give the answer just the logic. Yeah, consult them. Be a good engineer. You know, communicate, make decisions. Maybe sometimes provide your input on these things. Like, hey, I, we typically see this, but this is, you know, something we need to make a decision on together. So before we get into, you know, into diving into these foundations, I want to give a quick, quick overview of the ones we will get into. So we'll discuss shallow foundations, deep foundations, and kind of hybrid or more specialty systems. You know, each, each kind of system we'll talk about. There's different economics to it, contractability. It's not always just its capacity that we want to design for. So just remember that in this discussion. There's so many verabilities as we've discussed with soils that everything has a different thought on that. So before we dive into that max, the last pitfalls, lessons learned from a geotext standpoint, I just want to throw out there. And these are discussions, I feel like we're all having is designing before the geotext ready. Should we, you know, start making assumptions and diving into the foundations or really conservative assumptions and just requiring rework, ignoring settlement compatibility with our structure and our materials, not asking the follow up questions that are needed to make sure things are going to be put in a good place, misinterpreting allowable values. I think it's a really good thing to understand are you looking at allowable or, you know, ASD or LRFD values. Foundations are typically in allowable or ASD type values and not getting, you know, discussed from an LRFD standpoint. So I think there's some quick things like that. Also, I've heard that geotext want us to involve them in the design during the design phase. So showing them a plan to the foundations, the sizes, the loading you have and make sure they're on the team, making part of the team. There might be some additional cost to the owner or client to bring in the geotext for review. But man, if you got a complicated system or loading is weird or whatnot, so important to get there by off at that point too. Don't just take whatever their suggestion is and just go forward with it. I think it's good to call the geotext walk through things, understand it, some lessons. Yeah, ask questions. Don't design blindly. I mean, just some practical things. So with that max, let's dive into the foundations. All right. I want to start with one that I have a feeling, both of us and everyone that's hearing this has done. Zach, have you ever done a shallow foundation? It's a bread fun. Yeah, absolutely. Yeah, what is? Let me give you a better description. And my actual question is the foundation that we often see under residential homes outside of ocean landscapes would be a shallow foundation that goes just below a frost depth and it's continuous poor of concrete often thinner at the top with a wider section on the bottom, right? But in some regions, they do these wider single poor foundations. I would definitely say those are both shallow foundation category. They're often two to three foot deep. And of course, this varies by a frost depth, but that is what what I would call a shallow foundation. The mat is doesn't need to be to frost depth. So the interior doesn't need to be a frost depth because it's frost protected. And that is generally poured either over the foundation on the edge or right up to this edge. And so that is your line where you build the structure beyond that. It didn't ask that question very clear. We're basically thinking about strip fittings, first trench fittings, trench fittings are kind of a mid US Tansis Arkansas. I have not had that much experience with them. I don't love them, but they do exist. So has that had you done a shallow foundation? Yes. Yes. Okay. I would say what I mean, what's our percentage was? I had made this guess earlier like 95% shallow foundation. We occasionally do see some soil modification. So we're going to discuss rammed aggregate quickly later on. There's some other types of this, but you could still put a shallow foundation on rammed aggregate. That's just for the soil underneath. Shelf foundations are very cheap cheap system. They work fairly well, but you need the upper soil to be pretty good. That's not always the case, but for light structures, that's it's often enough. I bet from my experience, I experienced nine, almost 10 out of 10 buildings that I have designed or in part of our shallow foundations. I mean, it's unique situations for deep foundations come in. And again, probably more often than not. It's five stories and below has been my experience with shallow foundations and periodically needing deep foundations for very specific sites or very unique equipment that can have tolerances. Gosh, they got to be so tight and they can't move and deflections matter. So you go deep. But yeah, from my experience, most buildings that I've done have this continuous footing around the perimeter. And then some isolated spread foundations on the interior, potentially around the exterior to take some of those loads, combine footings or a big one footings. It's a bigger foundation that supports two columns or more pretty common. Yeah, there's some more exotic ones that I can't say have done a lot of. I think that are done more. But in my mind comes to come to my thought goes to Texas. And then I think you'd still consider foundation. It's usually called a slab on grade, maybe a little bit separate of a category, but I am a couple of those in my foundation categories. So we'll get into this. But that's when we get there now that we are sort of done. Oh, let me, my summary of shallow down foundation, you said almost everything here, but the, that is the baseline. That is where we all start in most areas of the country. If you have a lighter structure, that's fairly tolerant of a little moving and the soil underneath at high levels is strong. It's not ideal for expansive soils or classable soils. Any weak elements, it can't exactly span over and then the slab interior to the building is not modified soil generally, but that is the baseline where we start for almost all projects. It is the most cost effective. It's a decent amount of material, but like the labor, I've laid foundations. They don't, you don't have to be a pro and it comes out okay. Just comes to mind, I think is like interesting. I learned early in my career is the tolerances for shallow foundations. Like, you can't, like in the field, they can't just make them as big as they want. Significantly larger. The ACI has tolerances that, you know, how much smaller can they be and how much larger can they be. And I find that fascinating because I would have thought, "No, let them pour bigger. That's okay. That's, you know, that doesn't matter, but it really could. If your foundation's way oversized, it could affect things. If they pour the concrete wider, significantly bigger than the rebar, that could create some issues. So there's some interesting tolerances when it comes to foundations. Do you remember what these numbers are? All right. Let's each take a guess of a spread footing, how much bigger and how much smaller? I'm going to say zero, zero inches smaller. I'm going to say it can't be smaller, but it could be up to two inches wider. Oh, that was, I guess, I'm going to say half inch smaller, two inches wider. And I'm going to edit it right here. Ooh, ACI 11710, section 4.5.3. Variation from specified dimensions in plan plus or minus two inches or really half inch minus plus two inches for footing thickness. The level top service is plus or minus three quarters of an inch, but that really matter that much. Not that bad for a guess. If it ever comes to it, I'd take a look at all the details. So Max, how would you say a shallow foundation works from a load path standpoint? So a shallow foundation, we're just talking about bearing value at the base of the footing. There's any skin element friction from the side walls. This is the area that the load requires to distribute this out so that the soil will remain in place and the foundation doesn't move. We already mentioned the lowest end. We might be 1500 PSF, but you could certainly get up to 2,000, 3,000 pretty reasonably. It is just a bearing value of the size of the footing that we have. So the axially, we are taking the load down from the walls, the columns, whether it's landing on a pilaster transferring to a foundation or a bearing wall transferring to a foundation, it's going through a stiff element that will also help distribute the load quite a bit in span over any weak points, but our concrete wall that's sitting on the spread footing or the foundation wall helps distribute that wall load out to a bigger area. And then it's just a bearing. It's just bearing. What about lateral loads? How do we resolve our sliding forces? So that one is a little more involved. So we can bear laterally on concrete and we have active and passive soil pressures depending on which direction the wall is leaning. There's also a friction of the soil, of course. So when we look at wind loads on a building, the building isn't going anywhere. Why is that? That's a little bit of the soil friction that we have. The just entire area of the building has a little friction to the soil that it sits on. So from frankly, the passive pressure, when we look at wind pushing on a building, the passive pressure is a lot stiffer than the friction and that is taking all of the force of the building. Whoa, misspoke there. The passive pressure has to be engaged. The friction is there already. And so it's back and forth on what is controlling, but basically it has to move a little bit for the passive pressure to contribute. And then I think the last thing I wanted to add into, probably with most of our foundation systems, 60 KSI rebar, really common for most of it, you get into some more wild things, maybe higher strength. And then ACI has serviceability requirements for concrete strength. So depending on what category you're in, you might have a minimum concrete strength of 2500 or 4500 or 5,000. So those are things to think about as well. All right. The second style. Yeah, I think the next one would be helical peers. Oh, yeah. I know a little bit about that. Have you ever used helical peers? I have. Yeah, both in new construction and seismic retrofits. Ooh, okay. That's what I was going to ask is how often is it a retrofit? Because I have only used them in retrofits or if there is a sinking foundation often. All the ones I've done have been homes built on soft soils and the house starts to lean a little bit and they had a few tech reports. They say that we're going to need to basically, the soil is very weak. Using a helical, you're kind of using the soil in a different way. So if your top layer of soil is weak, you can with a helical bear a little bit lower and you can be on a better soil. You could be down 50 feet, you know, and still, if that's how deep it takes to find good soil and then just pour a column up that's fully braced by the soil. This is often just a steel column, right? And then the, then you've got the bearing value you need and the building will likely stop settling. In the IBC, there's a whole design procedure for helical peers with equations and something I found interesting is that they actually spec a torque. So once the helicals hit a certain torque, it's an embedment depth and a torque. So even if you've hit the right depth, let's say for this, specifically for attention because you need a certain soil cone above to pull this out. And there's a still torque that's required to put the helical in. So I find that interesting. When we looked at it for a long term solution for a brand new building, the question that kept coming up, which is fast as fascinated me ever since, is how long do they last? How long does it lie? You just put steel on the ground and it will last for your building. And I went down this rabbit hole of 10 deep. You're so full of oxygen. Yeah. Right. Yeah. So the helical company actually suggested doing thicker steel, assuming over 100 years, so much degradation or rusting would occur. So I found that interesting. I don't know. I think it'd be fun to deep dive into helical peers or other systems of, you know, for some reason, shallow foundations seem to just be a better long, I don't even know what I'm trying to say. It's a better long term condition, but seem to have last really long because that's what many buildings have been on for hundreds of years. So it'd be interesting to see like the lifespan of deep foundations too. Yeah. Yeah. I have nothing to add there. I want to throw in the history of helicals because I want to look this up like when did we start using helical peels, helical peers, because we've only been using mild steel for, you know, not that long. It's predates mild steel. It was invented in 1833. It did a lighthouse foundation, which obviously has a lot of uplift because it's quite tall. And yeah, that's. Wow. So we're almost 200 years. And I don't know if that building is still, it's still in existence, still standing, but we've been doing this for a while. And even at that time, they were using a torque measurements. So they were doing it less precise than we are now, but they were drilling the pier down until they reached a certain amount of torque that they knew they were stable, able to push down on the soil. The last thing I want to give, and I think it'd be interesting if, as we jump back and forth on a foundation types, give us sort of a strength value and a cost value, just a ballpark of what we're looking at here. I would put helicals, they're pretty strong. And especially because you drill them down until they're strong enough, which is really nice, right? If you find yourself a layer of poor soil and you have a shallow foundation, you're kind of thinking about what to do next, or if it's strong enough for a helical, you're just drilling until it's strong. Like I said, before that can be five feet or 50. The torque is what the requirement is. Besides some uplift made. Anyway, the cost though, it is medium to high. The material cost is not that bad. These do have to go through a supplier that you could derive some equations if you'd like, but you're often just looking at a supplier's table of what it can provide. And then they have installers that have been certified. So you're basically, you have to find. Some of them will provide a helical in your area of a certain style manufacturer. And then the manufacturer will tell you who to use to install them. All right, Zach. Keep telling me. Tell me anything about H piles because I don't know anything almost. Yeah, absolutely. Really, straightforward to describe an H pile is a wide flange beam and it is driven, usually pneumatically. It's got different pieces of equipment, but think about just hammering a wide flange into the ground. Very unique, I think system makes sense. I actually looked up and tried to find a geotechnical report online for driven H piles from a standpoint of values do you get. The one I found said that you get different values depending on what soil you're in. There's now two pieces of this that we haven't discussed yet. There's still a bearing capacity, which is called the end bearing capacity. This geotech report, depending on what soils you're in and where they stopped, was anywhere from 15,000 PSF and bearing to 150,000 PSF and bearing. That was from if the lower end was overburdened soils to the higher end being into bedrock. It seemed like a great project to put them straight into bedrock. The second piece of this is skin friction. End bearing, think of it the same way as your pad foundation, just bearing right at the bottom of it, right at the tip of the H pile. Your skin friction is the area around the shape that is in contact with the soil. The skin of the wide flange in contact with the soil is a surface area times length or the area of what you've got. With an H pile, you take it as a square shape. You times that by the length it is and then times it by the skin friction. These are additive values that you use from end bearing and skin friction. From this one I found it was skin friction of 1500 PSF up to 5,000 PSF or a big range there as well. Depending what you're going into, it could be really, really good. Another piece of H pile is now that they're installed vertically and as we talked about how do you resolve lateral loads? In gravity, these steel H piles go into some type of pile cap or grade beam that we put the building on. There's still a concrete interface there. We're thinking about transferring lateral loads. Piles are very stiff in gravity but they're going to move when you start loading them laterally. There's a means of software to design this, something a software that's really common that I've used and seen others use is called L pile. You'll get from the geotext, some soil parameters that could go into that software. There's many others as well. There's a spacing you provide. There's some guidance from IBC as well as your geotext. With a lot of these deep foundations, this would be considered deep foundation solution. It's specific to different sites when you might use it. I can't say exactly the site, but it seems from my research it's not a highly common deep foundation. With most of these deep foundations, we'll find that the tighter the spacing, the more overlapping they occur and there's a reduction factor in your design for tightly spaced piles for H piles. A quick little overview there. Do you know how closely can you space them on average, you might say? I'm going to tell you that I have a number in my head for helical peers and it's pretty darn close. Is H piles spacing pretty darn close as they say or is it, are we talking 15 feet? From most of the geotext reports I've seen when it comes to deep foundations, it's a three times the width from center to center. Okay. Yeah. So yeah, helical is also 3D. So maybe you're 5 feet. Okay, Max. So you walk us through rammed aggregate peers, one of our ground improvement solutions. Absolutely. So yeah, this is a ground improvement. It's not exactly foundation, but we wanted to make sure it's on the list here because it's used pretty frequently, especially in the area that I am right now. Utah, rammed aggregate peers are very common because there are so as here, whatever, 10,000 year old lake bed, 100 to the, I don't know. It's a very old lake bed, 13,000 lake on it's old dried up then. The soil is pretty junky up top and in a seismic sense, if that is undersized, it waves, it'll liquefy and we need to densify the soil and we do this with rammed aggregate peers. There's a few other soil modification styles, but rammed ag, I think is the most common US from what I have seen. I don't know. Chip in if you have any other ideas that year, but we're basically putting out like the three quarter ag you might expect in concrete in that style. We're putting that into a hole in the ground and vibrating it and hitting it very hard and driving it deep into this into the soil. The intent is not to make this column essentially. It is to make the ground denser and then the bearing quality increases quite a bit. It's from a material perspective, it's very cheap, time perspective, it's a bit expensive, but you get really nice bearing values and you can either do this in the line around the perimeter of a building or I have seen in some cases where you're building on an old trash dump. I did once and we did these helicals and I think every 20 feet or something. Just in a grid around to give the whole site a little higher bearing value and then we just use shallow foundations on top of this. It often comes with shallow foundations. It gives you really high soil bearing values and they're regional. You can expect them in places where they use often. If you have a building that fits the category, you're probably going to need them. That's my very quick ramdag peers but I think there's originality to it. I hope that sums up what you might expect to see in those. I've got a deep foundation one for you, Zach. K-Sons. It's a weird word. Weird foundation what do you got? I think to me K-Sons and bored and drilled peers or piles are all in the same realm. There's a lot of different techniques. The general way to phrase this type of deep foundation is that you are drilling a circular shaft into the ground to some depth. You're putting some amount of rebar in it and you're pouring concrete. You're filling it with concrete. This is another deep foundation where you have an end bearing condition as well as a skin friction. A big thing with the skin friction is depending on what kind of soils you have, you might not be able to get skin friction. The whole length of your peer and sometimes it's just what's embedded. There's some nuances to how those but a very traditional way of doing it. If you have good soils that will not slough off and fill in your opening. Let's say take a two foot diameter auger and drill a shaft to a certain depth. As you're drilling all the soils coming out, then you set in a rebar cage, a circular cage in there with some spacers so you can get your cover to the edges and to the bottom and then you fill it with concrete. That usually comes up and ties into some sort of grade beam system or some way to have lateral support. It's a big part of a lot of these deep foundation systems as you need lateral support in different directions. That's often done with grade beams. Now, if you have the bearing on the soil, are those bearing on the soil around them or are they bending of the pile? I'm not sure. For lateral pressure, if you have a grade beam around, are you using that to push on the soil? Often, a lot of these designs, you're still looking at an L pile. Your deep foundation is going into some bending action. It just depends on the geometry and orientation of your piles, your foundation, your grade beam. A lot of those systems, you're still looking at bending of that to transfer lateral loads. If you have water, you might encase your pier, so you might do steel casing around it, which that could affect your skin friction. The last thing I would say is when you're dealing, when you have a building with drilled piers, you're often just increasing your pier diameter where you have the loads and significantly. I'll jump forward a little bit and tighten. You might go from 24 inches to 48 inches or even an 8 foot diameter drilled pier, but to compare that to auger cast piers, very similar to some extent of the foundation. You have this continuous auger. This is where soils are as great and might slip off and fill. You have an auger that has like a hollow shaft in the center that can pump in ground or seam intelligence material. And, um, uh, You drill it all the way down and as you're bringing that that auger out you're filling it And so there's some there's some requirements of length of rebar in there often the cage may only be put It's usually often wet set it has to be because you're pulling that auger out and that might be only 10 you know Top 10 feet or 30 feet or something like that of your of your auger cast those you don't necessarily go bigger You go more so it'd be significantly challenging to do an 8 foot diameter auger cast So you might just add a lot of 16 or 20 inch or 24 inch where drilled peers They're usually just you're doing bigger drilled peers than more drilled peers is is common So all three of those casons board and drilled piles and auger cast peers kind of all the same realm of Vertical shaft going down to some good soil you can use skin friction and bearing In some sort of rebar in there with with some sort of grade beams and things like that attached You mentioned the reinforcing might not go down all the way does the geotech give a guidance on that and I assume This is the bearing value sort of goes away as you get deeper in the soil it transfers from bending the moment is higher at the top And then once that is fully carried out you're just on axial loading and maybe that's 10 15 feet down But just thinking is that coordination through the the geotech or they just giving soil Parameters and then you think about this run a little L pile cow and it'll tell you where your moment drops to near zero And you don't need to be enforcing anymore thing is mostly from an engineering standpoint auger cast really is is assuming and bearing Is what you're you're you're you're more or less relying on and it has kind of the same three times diameter for most of these designs So a lot of a lot of these deep foundation systems are really contractor specific. They're very specialized not you know every concrete Foundation company can do them. I'd say it's more often that most foundation companies can or subs can come out and build chalif Foundations but deep foundations take specialized equipment to drive steel wide flanges drill a huge Large shafts or auger cast peers now max. What about a waffle foundation? That's a that's an interesting one sounds like it tastes good A little syrup on there man the waffle foundation that's it all right So what the wall foundation is it's a slab basically that's stiffened by orthogonal grips These are generally one to three feet deep and they can kind distribute the load evenly across the building and so You're if you your soil characteristics are not excellent You can spread the load out quite a bit and that's you know whether we're looking at a wall foundation or PT slab I kind of fit those in the same category where we're just spreading the load out Using the stiffness of the slab that we're making we haven't been doing the wall foundations for that long We started this in the 80s and I would say it's better for lower foundation load So this is not a 10 story building exactly. This is your residential your one to three story lighter loading Specific to poor soils and so if you have an expansive soil if you have a weak soil layers This will kind of spread your loading out Uniformly so that you can avoid the pockets of soil that you would have some extra settlement for Let me give a quick mistakes ratios here ribs cut out for plumbing and So void forms. This is a common mess that just think about if you have to do this sort of system is that if you're running Piping underground or drain lines water lines. They're not that big, but You could do it under the system Not ideal certainly especially drain lines that are a little more collapsible Make sure you coordinate all those before the slab is poured and that you have details and you calc out the holes in your foundation here But you have everything lined up and coordinated so the building us water and things can leave if they need to I Think on a strength writing. I'm gonna give this a six It's it's pretty on good Relative costs maybe it's medium. It's a little harder to pour the system, but is just a fairly thin layer of concrete All right, that's what we're looking at for It's really just waffles. I hope I your appetite is Okay, anyway, let's look at my profiles. How small do they go? They go pretty small I Don't know how small you could go with them, but let's say on the order of like eight inches You might do might have one piece of steel down this down the center of it They are they are very small piles very small diameter and it takes you know minimal equipment A place you might have to come in from a retrofit perspective as well Yeah, kind of restricted sites underpinning existing structures or penetrating difficult ground conditions Would be another one is not something I have done a lot of I know there's maybe more or some other areas within the country that you You use them more often, but it's another kind of system that can be you guys I hear them come up a lot when doing it kind of Existing building things Hey, let's add micro piles or helicals or kind of some of these more retrofit options it seems like so Yeah, you still might get an end bearing value in a skin friction and you could you you often have a lot a lot more of these You don't you don't just have one pile like we've talked about you might have three or four in a group with a pile cap that then you're loading you still need Some system that's not going to see a lot of movement Maybe adding a new column load You know adding another floor to a building. Let's say trying to run these columns down Shallah foundations would be huge. They're offset, you know, because you're up against the perimeter foundation So you'd have maybe huge eccentric loads and so of the Shallah foundation might be challenging So you might come in draw some micro piles Add a pile cap to it Some differential settlement thoughts are still there, but Yeah, just really small Give me a quick rating cost and effectiveness That's a great question. I think With the right contractor I think cost is in the medium realm and then effectiveness is pretty high I think from a standpoint of deep foundations. They're they're really effective. They can see a tunnel load comparative to a one foot section of foundation sometimes Now throw on a back to you max sticking, you know similar to a waffle foundation maybe maybe but What about a mat and raft foundation? Oh Yes, you need a floatation that raft will make it happen So this is not for horse soil conditions. You still this is silly surface A surface level foundation. So I'll describe what it is quick. I'm sure everyone is picturing what this is or as you use this But a single large concrete slab that can support maybe many columns or wall systems But it's often one very large piece the core of the building in some cases So I've done a couple under a core buckling or shane brace system have a building and so we might have two grids of this building Maybe we were 25 foot wide by 50 foot deep. That's just concrete and then we've got a perimeter system But it allows us to put a higher load on a structure So compared to sort of the waffle slab PT slab. We're still putting these high point loads But we can distribute it a heck of a lot better over a stiffer element to a bigger area And so like PT and waffle slabs We're really just trying to distribute this load out to make the most uniform possible application of the soil a Mat or raft foundation is the way to take the biggest loads we might have and distribute them really far So I've seen mat foundations, you know 36 40 inches thick and we are We got a lot of reinforcing in these but the intent is to carry a pretty extreme stiffness and distribute these column loads high point loads out really far and so we can look at this in finite element style software This is not just your like how do you Your point load divided by area, right? This one takes a little more analysis You can make some pretty good assumptions on your shear and moment that you need to carry through the foundation But you should really be using a fem software for mat foundation analysis When to use this Settlement sensitive structures. So you're again, you're just getting a very big area And so if you're distributing over a large area, you're less likely to have point settlements higher settlement Let me do a quick Common errors here thermal cracking is pretty serious one. We have a lot of concrete news case You want to make sure that the reinforcing is placed to make sure this doesn't happen and That the foundation is basically protected from a ground water penetration and a little bit of cracking will not harm it too badly and it's just reinforced correctly We have some potential uplift due to ground water because we You are displacing a lot of water. If this thing is in the groundwater system, but I haven't seen that as a big problem. We can see these things all over the place, right? So I've used them for East Coast Utah, where I am now. I've done them a lot. I'm in the farthest west one. Washington, I do want to Washington. That is all over the place. And I rank these very high in strength quality. So I'm gonna put this up by my nine for strength, 'cause this has always been in my head. It's like what goes under a very large foundation, a 10, I think if it was on the. Yeah, I think 10 story building we had it. I don't know how much higher it goes, but yeah, 10 story building can certainly have a matte foundation at the core to just be those loads out. So I'm a big fan. That's my favorite one. What do you got? Yeah, and I've seen there is an article years ago that they were pouring a 16 foot thick matte foundation. It was a building ish. I don't recall, and it could have even been for like a retrofit or something, like where they had to come in and fix some things. But I remember that they had to run cooling lines through the concrete because of how hot it was gonna get and to try to lessen the amount of cracking that would occur. They ran a bunch of water lines through it and it was. That was very novel. What a grid it did. And 16 reed of the book, read us a lot. Yeah, the book big read about the Hoover Dam, also doing the same thing cooling it with water lines. I read us when I was in architects, so it really hit me differently, but anyway. Yeah. Concrete creates a lot of heat. Zach, tell me about piles. You got a heck of a lot of types of them here. Our last section. You're eight different types of piles. Hit me with what you got to pause it and bear in what are we doing with piles? Yeah, so composite piles, exactly what you think it is, just like our composite structures. Steel plus concrete or concrete plus timber or some combination and strength. We don't really have it on here, but timber piles are a thing. Think of any coastal regions with piers, pretty common. But you might incase it with concrete or steel with concrete to strengthen it as well as improved durability and performance. Our friction piles, pretty straightforward. Piles adjust work through skin friction along their length. End bearing, same sort of idea. Piles of transfer load directly to a stronger layer of rock or dense soil at the tip. They act like columns in the ground and truly just are just hitting that end bearing. So no friction and then friction piles, really no end bearing. There's other things, open casons, pneumatic casons. There's foundation systems that I've seen where they'll take a precast pier, more or less, like what we might cast in the ground and they might drive that into the ground. So, and that's pretty common in bridges and marine construction. So that might be our pneumatic cason. So there's a lot of different, there's like build casons. I mean, there's a lot of different options of deep foundation systems that you can get into. I find it fascinating of how many different deep foundation systems are, so many things we talked about, but PT on Slavon Grade, Waffle Foundation, Matt, Raff Foundation are kind of our, still kind of our thoughts of a shallow foundation system. But man, when you look at the deep, and that's what you see around the country. Yeah, the deep foundations, I think are a little more regional than the shallow foundation styles. If you find an area of the country that uses a lot of end-bamp piles or open pneumatic casons, like that is one of the things that they have in their tool belt. Of maybe six options in every state has a different six, eight options. To go back to where we started with all of this, you know, it's really like how do you drive and make that decision when you're, you know, jumping into a new building, maybe even in your region in the country, you've never worked there before. And I think the first step is relying on the geotechnical engineer. Even given them a call prior to them going out and drilling, I think can be, you know, very valuable. I remember before I moved from the Northwest to Colorado, I talked to a senior engineer and he said, "Oh, you're moving in the region "where they use a lot of cardboard under foundations." We always saw that was weird and it's called void form. And it's to make a space below the foundations or the grade beams, usually with a deep foundation system, to make sure that the swelling can occur without affecting the building. There's-- - You can mention that one. I can't believe that was on my list. It's the quick. So, you know, the soil can swell and it doesn't lift the soil, but we're also putting higher pressure at the points that did not have the void form underneath it. So we're making a more uniform, higher bearing pressure that soil cannot lift up. Sorry, that's my really quick summary of that one. - Right. - Because I can't-- - And then from, forgot it. And even, you know, we've talked about how robust these deep foundation systems are for the most part, but they run into their own challenges, definitely in the construction standpoint, a little bit in the design, but also, you know, a factor that plays into it is that swell potential can actually push your peer out of the ground if it's not designed appropriately. So there's a lot of weird things that could be occurring. So I think leaning on kind of that local knowledge, pretty rare that you're gonna find, you know, things that are rarely done, I would say, like it's probably a drilled peer or a shallow foundation are probably the two really common ones when you're debating shallow or deep. And then, you know, the waffle foundation, maybe more, when I hear more often the kind of a Texas region, Matt and Raff Foundation's are pretty nationwide as you mentioned, and then PT Slab on Grade, more regional as well. I have family that lives in Texas, their house was built on a PT Slab on Grade. And here in Colorado, I've gone by some places that I've also have PT Slab on Grades, which seem a little out of the norms. And I always wonder, like, are those just engineers from Texas? I don't know. I can see value on it. So with it, some manage, it's kind of dynamic all over the place. So we'd love to hear from you guys. Please reach out. There'll be a post about this episode on social media. Please comment on there, kind of what foundation systems you're used to using. And if we miss one or you've designed them all the differently, or something like that, please let us know. 'Cause I find it, it's such an important piece of what we are doing that it's good to share that knowledge across everything. Other thing that we didn't bring up that I thought was interesting diving into is Frost Protected Chalifoundations or FPSF. There's a whole design for that, and we're just gonna tease that here at the end. So I think to me, Max, I wanna give some kind of a wrap up and some takeaways here, and I'll let you do the same. But I think a way to preface a lot of this is foundations are system decisions, not just a check box. We went over so many different options in this talk that there's no like, I always check the box for you, we're gonna keep moving like there's so many different pieces that tie into it. A good geotech is important, but in addition of a good structural coordination can help save money and definitely risk foundations as a big piece of the risk equation. And if you're unsure, always ask often, ask early, such a big piece of all of this. So I think in a great sense, most buildings are shallow foundations, and a lot of places thinking a lot of buildings are very tall or residential, and sometimes you need to go a little bit deeper to benefit from bigger loads or from movement. So everything with foundations, majority of things with foundations are driven by movement. What do you got, Max? Wrap us up. - All right, I think my takeaway summary is that almost everything is on shallow foundations, but know what your region uses, what your other options are when you have higher loads. Or if you have very poor soils, you might not always be on shallow foundations. So we have a lot of tools available to us and know what your local industry is most comfortable using. That is really important if you can't find an installer that can do the system that you ideally wanna use. You're gonna end up with a worse quality system than you had thought about. So see what's common. It's probably gonna be a shallow foundation system. Think about settlement and the total bearing value and the big picture questions that you're answering and the whole system as you said, Zach. And I think that finishes off our foundation well. It was nice to think about this stuff in big picture again 'cause with the working world, you kinda get stuck in your series of, I use these foundations in the area that I work the most and I kind of know what the sequence is. It's most likely gonna be this style, but we get a report from the geotech. It confirms it's 2000 bearing and we just continue doing the same normal that we all live in different areas that has the. that prioritized different foundation styles. All right. See ya.