Geotechnical Engineer Abe Simantob Explains What You Need To Know When buying A Hillside Home

Geotechnical Engineer Abe Simantob Explains What You Need To Know When buying A Hillside Home.

Abe Simantob, P.E., G.E., D. GE

 L.A. PRIVATE EYES ENGINEERS perform geotechnical inspections for real estate clients.

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Contact us at 866-436-3647 or (866-GEO-ENGR) to schedule an inspection


A Geotechnical survey is a necessary inspection when buying a home on a hillside for many reasons. This type of inspection is outside the scope of a general home inspection. A home inspector will typically recommend a geotechnical inspection when homes are built on hillsides especially when obvious settling of building is visible such as floor deflection inside the building, foundation cracks, expansive soil or if the building is in a Soil Liquefaction zone.

Soil liquefaction occurs when a cohesion less saturated or partially saturated soil substantially loses strength and stiffness in response to an applied stress such as shaking during an earthquake or other sudden change in stress condition, in which material that is ordinarily a solid behaves like a liquid.

Expansive soils are those with excessive swelling clay minerals such as montmorillonite. The presence of expansive clay minerals in soils can cause excessive swelling when the soil comes into contact with water and also shrinkage when it undergoes drying. This condition can move the foundation up and down and side to side lifting wood columns off their concrete piers in some cases.
Expansive soils contain minerals such as smectite clays that are capable of absorbing water. When they absorb water, they increase in volume. The more water they absorb, the more their volume increases. Expansions of ten percent or more are not uncommon. This change in volume can exert enough force on a building or other structure to cause damage.

Cracked foundations, floors, and basement walls are typical types of damage done by swelling soils. Damage to the upper floors of the building can occur when motion in the structure is significant.

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Transcript

John Laforme: 0:00

Buying a home? Don't panic. Just listen to the rest of this podcast welcome to Home Inspection authority podcast with me, John laforme. Are you a homebuyer, a realtor, or maybe a home inspector? If you are, then this podcast is definitely for you. So let's get right into some straight talk about home inspections. Okay, everybody, welcome back to the show, John here from home inspection authority. And we're going to get into some straight talk about geotechnical engineering and what you need to know when you are considering buying a house that may be on a hillside or on compacted soil, and so forth. So I have a special guest here today. And his name is Abe Simantob from LA Private Eyes, engineers. How are you? I'm good. You know, last time I seen you, he took me to some sushi and got me really sick. True story. But I don't hold that against you. I know you didn't cook the sushi.

Abe Simantob: 1:22

This is where the good for trying to do a good deed.

John Laforme: 1:25

Exactly, exactly. But anyway. So I've known a for quite some time now five or six years.

Abe Simantob: 1:33

I'm better than that

John Laforme: 1:34

longer than that. Okay. All right, stand corrected. So, the reason why I invited Abe, aside from the fact that he's an awesome guy, and he's, to me, he's one of the best if not the best in the area. As far as come when it comes to geotechnical surveys, because he uses some tools that I've never seen anybody else use. And that kind of is a very positive thing when it comes to the inspection process of any kind of a house. Because I myself use all kinds of tools when I'm inspecting homes, because I think it's just easier way to make in your point. And I haven't seen anybody else but a user. That manometer That's correct. I said it right. Yes. Okay. So Manana, which is basically a water level. So why don't you give us a little info on that.

Abe Simantob: 2:47

You know, when people buy real estate, in Hillside areas, ideally, it would be nice to drill couple of holes to take soil samples to do lab testing. All of that costs a lot of money and takes a long time. So instead of visually eyeballing the house to see if it's level or not, why not do something that has sat there on the land at the property for several years, to see how it has performed? If I show our clients that the house is level after 50 years, it speaks volumes about how tight the saws or it could the foundations are. Whereas if I do my measurements and find out the house is tilting, then I question whether or not they did cut fill grading whether or not they compacted the Fill if there's a drainage issue. So every inspection that I do, John, I draw a floor plan of how the rooms are laid out. And I have this machine that's called them manometer water level is nothing. The basic principle of it is, when you have two cups of water that are connected together with a hose water wants to be at the same elevation between both cups. If I keep one of the cups stationary, and put the zero mark of a ruler next to the station and water level, everywhere else where I go with the second cup throughout the house, if the floor between underneath the second cup and the first cup is uneven, the wallet will move against zero and I know how much things are off. And when I change surfaces, from tile to wood to carpet, or if I step down living room, I take a double shot across all these transitions. So all the data gets adjusted to take into consideration all those variations. And then you sit back and look at the trend of the data if all the numbers are the same, that means the surface the slab or the floor is pretty level. Okay? Whereas if I find out that the numbers are, you know, trending in a certain direction either going up or down. That tells me there's some movement either due to expensive soils are settling filled soils. And the rule of thumb is usually that the movement is, in order for structure not to have a lot of cracks at the corners of doors and windows at the junction of walls and ceilings for you not to have perception of sloping floors or for doors and windows not to stick, the rule of thumb is that it's not supposed to building is not supposed to be off by more than an inch across a horizontal distance of 30 feet. It doesn't mean if a house has settled or move more than a couple of inches, it's going to fall down. It just explains the why it might be exhibiting some cracks. So okay. If a house is 660 feet long, it can be off by like two three inches. Without you having a perception of sloping floors. You go into some houses to get vertigo when you walk on the floors, because they're sloping, excessive

John Laforme: 5:53

is my daily my daily experience at work. You get flow deflection here. What's that mean? Well, I'm walking downhill over here. So actually, you're a little taller than me right now. So, you know, real quick back to the one inch to 30 foot rule. So just so people understand better. So basically, if I walk in the front door, and it's 30 feet from the front door all the way to the back of the house. And so you're saying one inch is allowed, which is typical settlement, right? For any, any structure, right? Correct. Okay, so that's normal. So want to be clear with listeners out there. It's my understanding, there's no such thing as a perfectly level house, that's great. And that's because they're built on Earth. And a lot of things can come into play, that can cause that to settle on one corner, settle on one side, and so forth. And that's, that takes us into the the whole drainage, and how important drainage is even in Southern California, sure, which I get resistance on on a daily basis from listing agents, listing agents pay attention, drainage is needed on all properties, especially if it's on a hillside. So it's really important to remember that and understand the importance because lack of drainage leads to inadequate water. Getting off the property, and it's it that's what leads to settlement, as opposed to other things. Yeah. So can you can you film, Can you fill us in on? Cut Fill? And

Abe Simantob: 7:36

sure, before I go to that topic, I wanted to elaborate a little bit more about this floor level measurement, okay. This measurement, like John mentioned, is crucial in assessing structures or properties. Because, you know, the last thing you want to do is, say somebody these houses sloping when it's not. So this is why you always want to measure. And without doing this measurement, you really don't have an idea of what's going on. This floor level measurement is not also usable. It's not only usable for evaluating settling due to geologic issues or movement due to expansive soils. It can also be used to evaluate deflection of framing, like a lot of people call me for condos and say, the floors appear to be sagging, Oh, yeah. And they're like on the second or third level of, you know, multi level structure. And I explained to them that I'm not a structural engineer, I'm a registered civil and geotech engineer, you know, but because of my civil engineering background, I also understand structures to some extent, but I don't want to pass myself off as a structural engineer, because those guys can also talk about roof and, you know, removing a load bearing wall, things of that nature, you know, but sometimes we see excessive sagging of floors, because of past leaks from kitchen or bathrooms, like when I do my measurements, you could have a house that's perfectly level in the lower level, because it hasn't settled it's on a slab or race foundation. But when I go do the upper level, it's significantly off condos, right. And the question is like if it was settling related wiring, both levels sagging by the same amount. So the deflection that you're seeing up in the upper level could be due to seismic shaking past water leaks or whatnot, or poor framing, poor framing, sometimes I could look at condos. And there's a significant sag throughout the whole unit in both levels. And the reason for that is because of the spacing of the columns in the garage, subterranean level below these units, because the cars are separate was to go through the spacing between the columns is more than the spacing between the parking stalls. And you get some units that are perfectly level and some units that have like three four inch sag. Yeah, I've seen it, I've seen it. Yeah, it was just measurements pretty good. Like John mentioned, this cut fill business. As I always tell people got doesn't create level building pads, people come in order to build houses, they make cuts in the hillside area and put the dirt down as fill in the low lying areas to compact it. And in the old days, when there was no requirement by the jurisdictions for involvement by geotech, engineer, soil engineers, people didn't compare the film as much as it should have been, there are certain things that we do, we remove all the loose dirt before we put the fill down, we bench the Fill onto the bedrock, puts up drains below the fill, so water doesn't accumulate in the Fill between the contact between the filling bedrock, these things are usually not done in the old days. And the net result is like John said, when there is poor drainage, when water saturates that fill, it settles and the bedrock doesn't and then you get the crack right across that cut field transmission line that goes through the building. And it does have to structure houses that are built across cut field transition lines also don't fare too well, in case of earthquakes.

John Laforme: 11:37

I mean, let me ask you a question before I go any further there. So how does one know that there's cut fail?

Abe Simantob: 11:44

Very good. When I do my measurements, after I draw a floor plan of how the rooms are laid out, first I look at the lay of the land right to see is this property located down slope of the road? Is it above the road, in the old days, when they used to do grading for roads, they would throw all the loose dirt on the shoulder of the road. So that's my first clue as there might be filled there, you know. And I also look at my data after I do my floor level measurements. If I see all the numbers from the road, to the far end of the house, or sloping uniformly in certain direction, it's probably a good assumption to say the whole building is unfill. And as you go further down the hill, the thickness of the fill is increasing. And that's why the is maximum settlement is for this away. Sometimes when I do my measurements, half the house, all the numbers are the same, passed a certain region, which we call the trans Cut Fill transition line, all the numbers start to dive. So that's how, okay, when the numbers all the same, it's probably a good bet that you're in bedrock. And when the numbers start diving down, that's probably whenever you're unfill.

John Laforme: 13:00

So it's your training and experience that determines all that and your and your specialized tools. Exactly. So let me stop right there for a second because I want to make it clear to any homebuyers or their realtors. A home inspection does not cover this, a home inspector does not have the credentials that Eva has. So if we see fluid deflection, you know, we make a note of it. If we see excessive cracking and drywall, the doors not opening properly, like along, let's say you're walking down a hallway and all the doors on the right seem to have the same sticking issue at the top corner of the doors. Those are notes we're going to put in and that's going to, and that's going to lead us to recommending further evaluation by somebody like Abe.

Abe Simantob: 13:49

or sometimes you see that score doorframes.

John Laforme: 13:51

That's true. That's true. So that's something I wanted to point out, because as a general home inspector, you know, we're generalists. We're not specialists like this, and a lot of buyers and the realtors just don't quite understand our scope. So that's what I want to I want to point that out. So if we say, Look, this house is built on a hillside, we're seeing a lot of flow deflection in one area or multiple areas we're seeing we're seeing physical, visible cracks in the foundation and one or more areas. We're going to recommend that you get a geotechnical and or foundation specialists out here to further evaluate the property because that means something

Abe Simantob: 14:35

and the ramification of excessive settling of the field, you know, when being you're on Cookeville is you can have cracks in the slab, you can have cracks in the foundations like you mentioned. It causes you know, a lot of people assume since the house has sat there 3050 years, therefore, there must be no issues you know, And I always tell them, that's the wrong assumption. It's like, I've been smoking 30 years, therefore everything is fine. Yeah. So just the fact that it has sat there doesn't mean it doesn't have issues, you know, these type of geologic foundation drainage issues are all big ticket items to address. Yeah, you know, when you have a leaky roof, maybe with 10 $20,000, you can fix the issue. Or if you have a faulty dishwasher, or whatever, you know, but when you have water intrusion into a crawlspace, or if you have excessive movement of a building that requires underpinning by putting some caissons under the vibrations to go through the field into the bedrock. All these are very expensive to address. So this is why you want to do these inspections before you purchase the property. And in addition to that cut, feel that I told you about the measurements tell me what's going on right? Before I go to an inspection, I also do some research. So depending on where the jurisdiction is, like in city of LA, they keep records pretty good. But some other areas, they don't really hang on to like Beverly Hills, Beverly Hills is not too bad. Okay. But some like in Pasadena, for example, it's very difficult to find a soul report for an existing structure, especially if it's older, maybe the newer ones have something. But like if there is availability, I tried to review the previous soil reports. And sometimes the grading documents tell you where the cut Ville transition line is how much they placed, or compacted was sometimes there is documentation on that it's good to know the history of the property to like if there was a landslide there that they repaired, I think it's important to the client to know about right.

John Laforme: 16:50

So what what tip would you give to home inspectors, especially new home inspectors, regarding inspecting a house that's on a hillside, or has experienced excessive flow deflection or any kind of, you know, major cracking anywhere on the on the interior exterior or foundation.

Abe Simantob: 17:14

Like you mentioned, you know, most of the time, even you know, if you don't see issues just to be safe, it's probably a good idea to do it. Like the example I always give people when I buy, I always buy my cars used. I don't buy brand new cars that buy them one year old with a few miles and I take it to a mechanic to check it out. And they're like, You're crazy. This has warranty why wasting your money? And I'm like, You know what, I don't know anything that was cars or mechanical stuff. I rather have somebody told me that it hasn't been heard is real. So when you see a lot of cracks, are these telltale signs or the issues or if you see steep topography, steep drop offs, causes too close to toe slope. You know, you really, like you said, don't know what stable today might not be tomorrow. So the best thing to do is it's expensive to do these inspections, but in the big picture is probably a good thing to do.

John Laforme: 18:19

And what is your basic cost for like a 2000 square foot house on a hillside.

Abe Simantob: 18:25

Nowadays, because I'm so busy overwhelmed with requests for this type of inspection, my minimum charges 2000 for houses that are 2000 square feet. Okay. But that's not just to look at the stability of the hillside, you know, this inspection everybody does it differently. A lot of my competitors are geologist and there are a lot of fine geologists. Some of them are dear friends of mine. They don't do what I do, but they know their business. In my line of work, I don't believe when you do a geologic inspections you're just interested in knowing how stable the hillside is, you want to also know how the geology is affected improvements on the land. So in addition to making sure the hillside is stable, I also check the house to make sure it's level because of adverse geology does not undergone excessive movement. I look at the drainage to see if is where does the water runoff from the slope go? Is there potential for water intrusion underneath the house into the crawlspace or if there's a subterranean levels, you know, is the water coming through the basement walls? I crawl on their houses check the foundations make sure the concrete has not deteriorated. There is no excessive cracking of all the seismic hardware. All the floor posts are straight. And then we followed up with a pretty extensive report with our pictures, measurements and recommendations. Yeah, so it's a lot of work between doing the researcher to see The end, you know, doing all these measurements and different areas that we inspect and putting the report together takes several hours to report to God.

John Laforme: 20:09

Now there's a lot of work involved, just like just like general home inspections, you know, I see you want to crawl spaces all the time. I'm always when I do see you under there, we typically hang out together. And I'm like, Hey, you see that crack? And you're like, Hey, do you see that water intrusion over there. And we kind of just compare notes. It's funny when we're on the under the house together. Sometimes we have these walk crawlspace we can walk around, which is typically on a really steep hillside. So you can, there's a lot of room in there. So you can see a lot

Abe Simantob: 20:39

this is actually I take a lot of pride in that because a lot of fellow inspectors like yourself, always tell me hey, we so strange to see you crawling alongside us in a crawl space, most of your competitors come out there and we are shocked. The guy didn't even go under the house. Yep. That's where all the action is.

John Laforme: 20:59

That's where all the action is. Exactly. attics and crawlspaces. Yeah. So anyway, so I want to get into a house that I inspected and then referred you to, and I want to explain why I went through that I came up with that conclusion that look, you know what, I'm gonna refer you to a geotechnical engineer to further evaluate this property, because there's been some major settlement here. So the first thing I noticed walking up to this house, this house is in the Glendale area, definitely, on a on what seemed to be a flat lot. But at the back of it, it's sloped down. And so you know, it, I can't tell you as a home inspector, if the house was on, cut, fail or anything like that. I'm just like, hey, you know, let's just check out this house and see what we find. And so the first thing I notice, I parked in the street actually parked across the street on this house. And then I walked up to the sidewalk, and the first thing I noticed was, with a curb touches the street was fine, that connection, there was fine. But with a curb, touch the walk with the sidewalk, I noticed a gap between the two. So then on the other side of the sidewalk, which is where the grasses in the driveway of the house, I noticed another gap. And I'm talking about a three quarter to one inch gap. And then as I walked more towards the house, I noticed at the other side of the driveway that connects to the garage floor, there was also a gap there as well. And I'm like, Okay, this is not normal, because this is not what I typically see on a daily basis. So that caught my attention right away, which then caused me to open the garage door, and then go in the garage. And inside the garage, I saw a good one inch gap between the garage floor. And the this is a slab foundation house, by the way. And there was also a one inch gap between the garage floor and the House Foundation, which is just where you step into the house to the garage door. And then to the left of that I noticed I noticed a pretty significant crack in the garage foundation. So and then I looked around the ceilings, and I can see stress cracks on the walls. And I'm like, wow, there's been a lot of movement here. So I couldn't tell right away if this was from maybe a past earthquake that really hit this area hard or what but I was like Okay, forget about the rest of the inspection for now I have to dig into this more. So I went out of my ordinary protocol when I'm when I'm inspecting a house and I just continued inside and looked at the floors real good looked at all the walls and ceilings. Amazingly, inside the house, I didn't really see much stress cracks or anything weird like that. But then when I walked around through the garage to the front door, I noticed there was a crack right across the front entry, which was in direct line with the foundation in the garage if it went left to right. So it's hard to explain this through a podcast but doing my best. So I noticed that and I and I kind of realized, well, maybe maybe there's some fluid inflection here. Let me let me see what's going on. So I use a default laser level, you stick it on the floor, turn it on, and it shoots a red beam all the way across. And i i If I remember correctly, it was between four and a half to five and a half inches of floor deflection across this 30 foot. This 30 foot span of house was about 30 feet I guess. And I was like wow, that's really significant. But the funny thing was you couldn't really see it when you first walked in the house. You couldn't like Feel a downhill slope you, it was kind of it was kind of an anomaly was kind of weird. To me, I was like, let me check that level again. So I checked multiple times to make sure I wasn't crazy. And sure enough, there was a four and a half to five and a half inch drop from the front of the house to the back of the house. And I went upstairs and I got a similar reading up there as well. So this was when I recommended Abe come out and check out this house. And so I'll let you elaborate on that. Because I can't go any further on that as a German Home Inspector, I see. I was I can tell my customers look, you have major floor deflection as major settling here, it seems to it seems to me that the whole house, one side of the house has dropped significantly compared to the other side. So it wasn't a it didn't seem to me like a crack in the middle of the house with a slab cracked in the middle of the house. It didn't it just seemed like the whole house just tilted like that. Yeah,

Abe Simantob: 26:01

yeah. I'm very familiar with that property. And when I did my research, I found out that there was that whole lot was a fill lot. Oh, so as you went away from the street, the field thickness increased. Fill soils are like a spring, if we have two springs that have the same stiffness, the one that's shorter compresses less than the one that's longer. Even if the compact the soul the same amount, right, just because the fullest sticker, you get more settling in that area as compared to areas. If an area is underlined by five feet of fill, it compresses less than an area that's underlined by 30 feet of fill, I drew a floor plan of that house that we're talking about. And this is both the upper and lower level. And this is what I was telling you, I recorded dimensions of how long and wide the rooms are. So I know what distances My measurements are acting. As you can see here, we have deflections that are like five, five and a half inches. And the reason we want to know about the amount of deflection is because excessive deflection can cause all sorts of problems. In addition to cracking and sticking doors and cracks in foundations and slab broken windows. It can also cause separations in roof, it can get roof leaks, you can get separations between roof rafters and the ridge beam. So it's best to the extent possible to have a level house as compared to one that sloping, you know, sure. And this explains basically what's going on. Now, the big question that a lot of people ask is, okay, is this done and over with, you know, Is there potential for additional settling, you know, when I deal with houses that have five, six inches of settling, I usually recommend further investigation because of the magnitude of movement by who, by someone like myself, there are companies that come and drill holes in the ground. take soil samples, do lab testing, okay? Soil Investigation is different than the geotech inspections for escrow geotech, when you're in middle of Escrow Time is of essence. So people usually don't have the budget to spend five$6,000 for solo report, they can wait for six weeks for the results to come back. lab testing takes time analysis takes time. By that time, usually when we find issues like this, when we say we need further investigation, most clients usually walk isn't it becomes really the sellers issue. They have all the time and all the money and budget to tackle this, right. You know, underpinning buildings. You know, underpinning is when like this house that we're showing that there's like excessive movement settling five inches. To stop it from additional movement, we have to come and put case on these wrong concrete columns that go underneath the foundation, through the field into the bedrock. And depending on how deep the bedrock is, the cost could vary all over the place. So that's why you need a subsurface investigation to see how deep the feelings sometimes those previous soil reports that you have have that information to like how thick the fill is how deep the bedrock is, but I don't do this type of work because most of my clients don't want to spend that type of money but for past 39 years, you know, that's all I used to do the right soul reports and do subsurface investigation. Oh, that's

John Laforme: 29:52

what you used to do.

Abe Simantob: 29:53

Exactly.

John Laforme: 29:53

Okay. So nowadays, that's so to be clear on on what your your scope of Work is. So you're a geotechnical engineer that does not include soil sampling. That's correct. Okay. So if you could, if somebody wanted to hire you for it,

Abe Simantob: 30:10

I don't have the equipment for it. But I know how to do these things. As I said, most clients don't want to spend that type of money to purchase a property, or to fix it, right? There are companies that do that. But for real estate transactions, because I'm so busy doing these inspections, and people don't want to spend that type of money, I haven't bothered to set up $100,000 lab and, you know, set up all this,

John Laforme: 30:36

I understand. So basically, if you're buying a hillside home, and you finish your general home inspector inspection, and then your home inspector recommends a geotechnical survey, then somebody like Gabe can show up and take care of that. But then at that point, he may recommend a soils

Abe Simantob: 30:57

depending if there is excessive movement, and there is need for substantial repairs. We remember when you try to pull a permit, or most of these repairs from most jurisdictions, because they are in a hillside area, they're gonna require a subsurface investigation or soil report. Okay, so you need to do that anyway.

John Laforme: 31:18

And what do you think of souls report? What cost?

Abe Simantob: 31:20

They usually start at like 5000? Nowadays?

John Laforme: 31:23

Okay, so yeah, that's, that's a good amount of money. $5,000? Yeah. Yeah, that's a good amount of money. Okay. So as far as that this particular house goes, your final conclusion was

Abe Simantob: 31:38

it, there's potential for additional settling, when the fill, like say they filled in a canyon, right. And the house is 67 years old, and it's settled three, four inches. What I always tell my clients is with good drainage, so there's less potential for that fill getting wet. And barring large magnitude earthquake, which can damage any property, probably the potential for significantly additional settling has been diminished by now because settling of most Souls is usually over after the first 1015 years of construction. But that's because the Fill has confinement from the sidewalls of the canyon, or if you have a retaining wall, it can't go anywhere anymore, right? But if you have a free face, like the Phil slope, and the House has settled five inches, who's to say that it's done and over with, it can go under,

John Laforme: 32:36

there's no support below it? Exactly. There's no such there's no retaining walls down there.

Abe Simantob: 32:41

There is no sidewalls of a canyon, so you can still undergo some movement. The problem with uncompacted soil is not only the downward settling movement, it's also lateral stability. They can you know, a lot of these fill slopes fail, they have slope failures, you know, that are also expensive to repair. We haven't even talked about the expensive soils, which could be

John Laforme: 33:08

we're going to Yeah, we're gonna get into that too. So yeah, understandable. I you and I did another house. years ago. I cannot remember the address that saved my life. But it was in such bad shape. The slab in the it was a raised foundation and a slab foundation combined. On one side of the house and the slab. I literally tripped over it. When I was walking in. There's a shag rug over it. You remember that place? Yep. And

Abe Simantob: 33:40

Sherman Oaks in Encino. So I think it was Sherman

John Laforme: 33:43

Oaks in the hills. And yeah, and, and I remember tripping. I'm like, what the hell I just tripped over. I thought I was walking on carpet. And then I pull back a little bit. And then I could see that there was like an inch and a half crack. Which means one side of that slab was dropped down an inch and a half from the other. And the house was literally no exaggeration riddled with stress cracks on every wall and every ceiling.

Abe Simantob: 34:14

Now in those situations, we are kind of fortunate because the house is talking to us. Yes, it is the fact that it's exhibiting all the cracks and these telltale signs it we know there's something going on in addition to getting that feeling when you walk you have a perception of sloping floors, right? The houses that I hate are the ones that have all these issues. But the flipper whoever is selling it has cosmetically painted over all the axes. You'll see anything. I'll be darned if you say there's issues and he'd be doing some she says no issues. Yeah. And it gets so many phone calls from disgruntled clients saying I bought this house two months ago. It was pretty relatively we have had a seven year drought You haven't had significant rains. And when we get these heavy rains the house 32 pieces. Yeah, not fun.

John Laforme: 35:08

There's, you know, I did another episode on the podcast about why your drywall cracks and what's what's considered normal what's considered, you know, not normal. I did a whole episode on this. So I'm not going to go back into that right now but just for the homebuyers out there understand if you walk into a house, the one I just mentioned is, like I said was riddled with cracks. They were everywhere. And I couldn't believe I was hired to inspect the house. Because it was so obvious. There was big issues here. windows were broken. The frames were bent from all that settling, unless I

Abe Simantob: 35:43

don't know, I don't think it's maybe Earth good damage. Yeah, you have to you know, as long as you know, it was a one time deal, I patch the cracks and life goes on. But when I do my measurements and find out the house and settled so much, and I see all these cracks, I usually tell my clients, you know, if you don't fix your foundations, if we don't stabilize the house is a good chance that these cracks are going to come back even after you patch them up. Yes, and nobody wants to buy a $2 million house nowadays. And Ray cracks showing up after you spend 200,000 Exactly modeling.

John Laforme: 36:21

So now I'd like to hear your opinion on expansive soil and why it's only in some neighborhoods and not all neighborhoods.

Abe Simantob: 36:29

Sure. Expensive soil soils is something that's opposite of settling soils. And that's usually associated with clay, soil, right. Even bedrock, you know there is different types of rock there's different types of soil, we have sandy soil, we have silty soil we have clay soil and same thing with bedrock clays, bedrock clay stone, you know, shale, depending on the clay content of the soil, the soil can become expensive, expensive soils or soils that heave shrink and swirl with changes in moisture content. That's why having good drainage around properties are of paramount importance. If you have a bucket of sand and you put a couple of jars of water over and there are holes at the bottom bucket, most of that water comes right through right with expensive soil because the soil is comprised of clay particles which is which are really tiny, those clay particles have an affinity towards attracting water molecules and when they attract the water molecules, the soul heaves it it wants to expand with bloats so if you have a bucket of compacted clay and you put water on it and have time to see that water percolate into the soil chances are very little water comes out of the bottom of the bucket because the clay absorbed all that sponge exactly like a sponge it attracts all the water and then unlike the settling that the building goes down, expensive souls can push this slab or the foundations of structure up post in pairs. You go underneath the house you see all the posts on piers are elevated above the concrete pads they were supposed to be sitting on it you see cracks in the foundations you see cracks in floor slabs because the sole push the building up. Yep, they can be very damaging. I've been to some houses that because of expensive soil. There were separations between the roof rafters and the ridge me I've seen that I've seen all that it can be also very damaging and the reason they're in some areas and they are not in some other areas is because of the clay content. Like a lot of parts of 1000. Oaks Calabasas are notorious for having expensive so it's torrents some areas that are you know normal soil like silty sands or you know sandstone or things like that don't have expensive source granite. The more granular the soil is the less expensive it is

John Laforme: 39:21

right and typically you can identify the expansive soil by the shrinkage cracks.

Abe Simantob: 39:25

Absolutely. After the soil dries up, you see pretty good, deep and wide shrinkage cracks into the subgrade soils in the crawlspace. Like a Utah desert. Exactly. That's what it looks like around the exterior of a building even.

John Laforme: 39:40

Yeah, I very rarely see it around the exteriors mostly see it in the crawlspace and then when I go into like a 1920s garage, the floor is heaved up. Exactly. And everyone's like what causes that well, just it's lifting up in the middle. I can't see expansive stuff. boiler shrinkage cracks around the outside, so I can't tell them that's what it is. I just say, Look, you probably gonna have to jackhammer this up, replace it and report. Yes, that's pretty bad.

Abe Simantob: 40:10

And also, to make sure it doesn't come back after the replace the slab, they have to remove the upper two feet of the subgrade soil below the slab. Oh, I didn't know that Emery compacted with sand. So ah, because, you know, you haven't addressed the mechanism that led to the cracking of that slab in the first place. So even if you repress the slab, it probably come back unless you treat the soil. Since we are on that topic, you know, this measurement that I told you that they do the floor level survey, sometimes they see houses that are perfectly level, and the slab is cracking to pieces. And they're like, now what, like when we do a lot of older homes. This is where my civil engineering background kicks in. As we know, a lot of older homes pre 1960 didn't have steel rebar reinforcing in the slab and concrete in absence of steel rebar has very little tensile strength and without rebar, concrete cracks. So combination of lack of steel, rebar and poor soil conditions, poor drainage conditions, you can see what it can do to the foundation or floor.

John Laforme: 41:23

So are you saying that the pre ninth would you say pre 1960s? Yeah, pre 1960 slabs didn't have any most of them didn't? Really? Yeah, so it's just straight concrete?

Abe Simantob: 41:34

Yeah. If you were lucky, they had what we call a welded wire mesh. Just to keep the concrete together. I say no, it didn't prevent the slab from cracking, it was just the concrete stays intact. The logic back then was if the slab is not supporting the load bearing walls, why bother reinforcing it. And then when people started seeing cracks in the flow styles and attorneys got involved, the papers got smarter. They said, Okay, steel rebar is cheap. Let's throw some in the slab while we're building the house. So even with doing that, like you said with the settling of soil or expensive soil, they were seeing some cracks in reinforced house slabs in houses. And then they went to even a more elaborate system. We call it post tension slab. I just gonna mention that Yeah, yeah, nowadays we have even more elaborate foundations to deal with difficult soil conditions, where you know, you have potential for significant settling or expansive soils. They have these really thick concrete slabs with high strength steel tendons that they lock the stress into the slab before they build the house on top of it so it doesn't settle or crack anymore.

John Laforme: 42:57

And that's typically stamped into the drive to the garage floor,

Abe Simantob: 43:02

the garage floor slab in a corner. Yeah. And that's usually for houses I would say within the last 1015 years. Yeah, I did a lot of land development in Magic Mountain, northern LA. And a lot of developers put post tensioned slabs. And like John said, there's usually a stamp in the corner of the garage slab that says do not make cuts in

John Laforme: 43:23

this slab very important people listen up, a lot of

Abe Simantob: 43:26

people like to go and put the jacuzzi or safe or something below their slab and they're like, let's go ahead and make sockets in the slab. You're asking for big potential injury. Yeah, because if we got any of these high tension steel tendons and they snap, they can cut your neck or face in half, we really want to be careful. If you really want to go there, I recommend you don't but if you do, you need to talk to somebody professional, or somebody to at least do some x raying to see where these 10 Maybe you can do it between those tendons but not don't cut the tendons.

John Laforme: 44:05

Yeah, so be careful out there all you di wires like Oh, I'm gonna install this car lift and my garage floor whatever you gonna do, if you see that look on your garage floor it's usually in the right or left corner by the garage vehicle door right it says post tension concrete slab do not cut and that that's there for a reason. So if you have to do something in the garage call the qualified professional to walk you through it so you don't kill yourself or anybody else in your house because that's that's dangerous, very dangerous stuff. One thing you just mentioned so back sit back in the day when they were there when the logic was we don't have to worry about the putting a foundation underneath load bearing walls if they're not load bearing walls, right?

Abe Simantob: 44:54

Right the floor slab in the middle of the house but

John Laforme: 44:58

they're technically is load bearing Walls unless you're on a truss system, right? So if it's a complete trust system that may not be considered load bearing walls, because the trust carries the weight of most everything,

Abe Simantob: 45:11

or sometimes they have these big girders that span between columns and right, we'll have partition walls.

John Laforme: 45:17

Yeah. So the frame houses so that that's why I came up, Mike. Well, yeah, I guess that makes sense to a point. But there's a lot of walls in between the perimeter walls.

Abe Simantob: 45:27

And also this settling or expensive soil business scares a lot of homeowners. I get so many phone calls saying, hey, my house is creaking and cracking all the time. I hear these loud bangs middle of the night that

John Laforme: 45:44

we're sitting at right now it does the same thing.

Abe Simantob: 45:46

You know, sometimes because of that movement due to expensive soiled when the house is moving, all this framing is moving relative to each other. And that's the noise you hear. Sometimes you also get creaking squeaking of structures due to thermal expansion contraction of a building during hot summer days and cold nights. Yep.

John Laforme: 46:09

That's what happens here. Yeah. Oh, yeah. I'm pretty confident. That's what it is. That happens here.

Abe Simantob: 46:12

I had one of these house was next to a steep drop off a cliff. And this woman swore that he after you, we bought the house and you suspected that I am hearing creaking and sounds. And I'm so scared that the house is sliding down the hill and something is happening here. Or maybe you haven't called Ghostbusters. Yeah, you know, and I couldn't understand, you know, I went underneath the house, it was dry. I didn't see any cracks in the soil. That telling me but an imminent slide is about to start it and we sat in that living room for half an hour to see if there is a sound or something. And then one day when I was driving the light came on. And I said I bet with you she's having expensive soil issues. Because they didn't put any of the drainage that they recommended around the building. I never do. Yeah, after they fix it. They never called me back saying they have this sound anymore. Ah, so to reduce the potential for settling and movement due to expensive sores, stop the bleeding. Like John said, you have to fix your drainage. If you don't stop the source of what's causing the soil to either Hiba or settle which is poor drainage, the problem with doesn't go away. So like John said, 90% of houses that be inspect, they usually have some kind of a drainage, they rarely is the question of them falling down the hill, right? It's like, hey, this house is cracking, because you have water accumulating underneath it. And depending if the soil is clay, it gets pushed up. Or if it's loose filled, it gets settled down. So you go to some houses, the crawlspace is bone dry. But then when you look at the stains against the footings, you know there has been flooding in that crawlspace before or if you see the shrinkage cracks in the soil,

John Laforme: 48:06

every time there's a heavy, high water table underneath the house or actual, you know, inches of water, it's always going to leave a brown stain around the foundation, it's really easy to pull it's real easy to see other period posts and pairs as well. It's real easy to see it's like wow, there's like a small lake on the hair at 1.0. You

Abe Simantob: 48:26

see a lot of efflorescence that site white salt right up on the foundation stone walls which fills the water set next to the footing and is migrating to the concrete into the curls

John Laforme: 48:37

and that leads to spalling which is a much worse condition. Yeah, all that. So okay,

Abe Simantob: 48:42

getting back to this expensive soil or even settling. We talked about how these different types of performances affect the building. These expensive soils can also cause havoc with retaining walls. I just did a house in Bell canyon that was 10 feet tall and it was out of level by 12 inches deflected what I measure the level of you know plumpness of a wall with using a plumb bob I have a string with a way to do it that idea. And because the soil was the backbone of the wall was clay. When water accumulated behind the wall, the soil pushed the wall out and it was crazy to know retaining walls are not cheap. They're like 400 bucks a square foot. So if you have a 10 foot high wall that's 50 feet long, you know, do the math, you know how many 500 square feet it's like 20 $30,000 You know, repair sometimes if they don't backfill the dirt behind the wall even if it's not clay, if you see when you squeeze soil inside the cup, the wall sidewalls of the cup don't even feel the pressure of the soil. But if you pull the soil without any compaction into that cup, the walls of the cup feel the weight of the sword. So that's why we want to backfill the dirt behind the wall. So there's not too much pressure on the wall, if the soil is loose, all that weight gets transferred to the wall.

John Laforme: 50:16

Right and and also, let's talk about the other side of that is when someone's, you know, redoing their backyard, and their house has a retaining wall holding up half of their half of their soil that's between the the wall in their property and the actual house. You can't just remove that and expect nothing to happen. Well, it's there for a reason.

Abe Simantob: 50:36

Well, sometimes I've seen the opposite of it. They might have a little slope around the house, and there's a retaining wall there. And they're like, oh, wouldn't it be great if I had the level backyard, and then go slap some bunch of additional bricks on top of the existing wall and then put the additional dirt behind the they basically extend the height of the wall and put the added weight on it? Well, good news for you just the wall is gonna mean Yeah, because they didn't reinforce it.

John Laforme: 51:05

Exactly. Exactly. So let's talk about liquefaction. Mm hmm. Why I can't explain that. Let you explain that.

Abe Simantob: 51:16

liquefaction is happens when you have a stronger copiously and you for it to happen. You need several things to be in place, shallow water table, loose, sandy soils and stronger quick. These are typical situations. I was part of a committee that put together the guidelines for evaluating liquefaction in Southern California and you're the right guy. I think I know liquefaction pretty well tear. That type of you know loose soil conditions is usually present like in Marina Del Rey venice beach or in San Francisco marina district where a lot of houses sustained damage due to liquefaction. The best way to explain it is like if you envision loose sand like a bunch of billiard balls sitting point to point when there's an earthquake, say billiard balls, billiard balls, okay? That mean like a pull table and table. If they're sitting point to point and when there's an earthquake, that the earthquake forces migrate and come and hit the water table at the property, it causes the water to boil, and these billiard balls are loose sand particles falling between each other and then the ground settles and then you get cracking building and all that you get sand balls coming out of the ground because water wants to come up through the soil. But as I said, that's more of an issue. Your areas that truly have shallow water table.

John Laforme: 52:50

Set Marina del Rey right Marina del Rey, I just did a property there beach. I just did a property there about a month ago. And the realtor mentioned to me at the end of the inspection, after I told him what was going on under the house, I had an excess of moisture under there, the rebar and the the stem wall was completely exposed in one area. And it it split, like 10 foot section, a horizontal split, the rebar got wet and expanded. Yeah. And I was like, wow, that's that's a pretty bad condition. So and then he mentioned at the end, by the way that was told this was on liquefaction. I said, Okay, well, yeah, there's a lot of things going on there no drainage either.

Abe Simantob: 53:31

Yeah. That liquefaction the nerves dissolved is that some settling and movement and again, when I do my measurements, if I see the houses out of level in the liquefiable area, then we attributed maybe due to liquefaction. You know,

John Laforme: 53:47

liquefaction only happens if there's an earthquake,

Abe Simantob: 53:50

exactly. Exact or if we have a heavy vibratory equipment that causes the soil or the foundation to shake a lot, but that's usually not prevailing in a house, you know, right. But going back to what you were saying about the I get phone calls from a lot of people saying, Oh, our home inspector saw a lot of horizontal cracks and the foundations like in palace where the area or Venice or Marina del Rey what happens if you don't even have to have liquefaction you can have an area with poor drainage, this can happen. Sure. What happens is when you remember I told you the foundation stone wall has a heavy efflorescence on it. Yep. That tells you whether sits next to the building, maybe in a planter or if the slope water runoff negative grade. Exactly, you know, what happens is when that moisture sits in next to concrete, it migrates in and corrodes the steel rebar. And when the rebar, corrodes, it expands. And that's when you get that horizontal crack in the concrete foundation. In extreme cases, it can cause the concrete to spoil off and you see rebar exactly what I saw. And unfortunately, if the rebar is shot, then you can't just go and epoxy that crack and say you're good to go. The reason we've reinforced our foundations with steel rebar is because again, concrete has a bit of tensile strength. And with that steel rebar, turning into powder, there is no more of that. So you kind of need a sister foundation or foundation placement in that game.

John Laforme: 55:25

That's what I mentioned to him, I said is probably what's gonna that's probably what a foundation guys gonna recommend as a sister Sister that up.

Abe Simantob: 55:31

Yeah, nowadays, when we deal with liquefiable soils, we, if possible, we like to put the building on driven piles, they come and actually hammer the piles down into the ground. Or they use what we call a matte foundation, we put a really extra rigid slab underneath the structure. So if there's settling, the building doesn't set it doesn't crack, you know, right just settles. I, you know, after Northridge earthquake, a lot of people complain that they're having cracking of building either due to being in a liquefiable area or in a seismically unstable area. So the city of LA or state of California put these maps together that identify areas that could have potential liquefaction, or could have potentially seismically unstable slopes. And that's based on some of the existing boring data, you know, subsurface information, how steep the topography is, how shallow the water table is, they have groundwater wells around the lake, so they know how high the water is, without any regard to the soil type. So there are parts of Westwood, Beverly Hills Valley, there are even in the canyons, you go like Mandeville or cold water. They say the soil in the bottom of Canyon by cold weather is liquefiable. But you're nowhere near having a shallow water table or being near Venice or Monterey. Again, that's based on you know, when there's runoff from the hills and all the water migrates down to the bottom Canyon, it flows down the center of Canyon. So they're saying during rainy seasons, there could be some moisture running down the Coldwater Canyon. So therefore, the sole might be liquefiable. In that case, when I come and do my measurements, and the house has been there six years and is still level, and you know, liquefaction hasn't occurred there. So, again, it all goes with the soil type, locality knowledge of the area. I have been fortunate. I've been doing this for almost four years now. And I know on time Yeah, I know LA area. Most of my inspections are in LA County. I do cover some southern margins of Ventura like Cambria and Ohio or I go on the east side near Pomona. As for Donna's palace where they that area, right I don't like to do inspections out of the area that I'm familiar with sure that local experience is really of paramount importance. Like if I get a call to go inspect a property in San Diego. I don't know the geology of San Diego like I do in LA.

John Laforme: 58:20

Got it. Okay. So no Orange County house calls.

Abe Simantob: 58:24

I mean, they can still do it. But you know, it's better if I'm so busy covering stuff in LA. I usually don't have time to go there.

John Laforme: 58:34

Right. So well. That is about it for me. I think I think we covered a lot. Do you get anything else you want to add any tips? Any tips for a like let's say a brand new home buyer that's going to be buying a house on a hillside any tips you want to give them any tips you want to give a new home inspector?

Abe Simantob: 58:57

I always when I get phone calls from because let's face it $2,000 is not chump change. It's a lot of money. Right? And I'm plenty busy when people call me and they're on the fence and you know they are not sure what to do. I always tell them listen, your best line of defense in all honesty is a good home inspector. If your home inspector goes there and his experience doesn't see any cracks, the floors look level the slope is not too steep. The house has been there for a long time. Chances are you don't need me. Right but if your home inspector comes and tells you there is a lot of issues and all the stuff that John has been talking about, chances are when I come out they're able to find more problems and you got to be confirming what I feel just confirms it and put you know explains to you why things are the way they are. So having a good inspection is really important. And also for a peace of mind. You know I have dealt with brand new houses John that, you know, I charged some guys$6,000 For like a $25,000 mansion that was brand new and he was uneasy. This is this is a, you know, $25 million investment, I want to make sure they bought this right? And I said, No, you're gonna pay a lot of money. And he calls me back and says, you know, a lot of my friends are telling me I'm stupid. I'm like, why is Jesus all approved by the city? Why are you having this guy come and inspect everything, you know, when it's all approved? You know, I said to my clients, you know, two plus two and papers always for, you know, what was drawn up on the plan. And whether approved by the City is one thing, how they bolted in the field is different thing that's called earth one. Lo and behold, I show up on that property, really high in house. I look at this retaining wall that's not even shown on the plans. Like where the distinct come from. And I look at this thing, and I'm like, I can swear this wall looks like it's leaning. It was 15 feet, it was hard for me to go above it to hang my pride up to check it out. And the developer, soil engineer tells me you're dreaming. Your eyes are crooked. Are you talking about? We don't build your eyes? Yeah, we don't build walls that are that much. 12 inches out of level? You know, I said, Oh, yeah. So we got the ladder and wind up here. And sure enough, we show them that the wall was not straight, and the guy couldn't believe it. And he walked away from that deal.

John Laforme: 1:01:37

Yeah, well, let me let me add a little more to that

Abe Simantob: 1:01:40

building a 15 foot high retaining wall is not cheap. Right.

John Laforme: 1:01:44

And just because something is new, doesn't mean it was done correctly. If that was the case, I probably wouldn't really have a job. Yeah. And you wouldn't either.

Abe Simantob: 1:01:53

If everything that got approved by the city was problem free, we would both have a job,

John Laforme: 1:01:58

you know, adding on to that as well. A lot of new houses, I do have little to no ventilation under a crawlspace brand new properties and like, Ah, I hate when that happens. Because now I have to tell these very excited buyers that they're getting. I mean, these houses are beautiful. And I have to tell them, by the way, you're gonna have a major moisture problem on your house. Yeah. You know, there's no ventilation

Abe Simantob: 1:02:21

as we both know, when you go underneath the house, when you turn off that flashlight, if it's pitch dark. Or if there's a lot of compartmentalization. You know, interior footings and stuff, you go from one corner of the house to some other you don't see any openings. You have poor ventilation, and that's when you need to add fans, ducts, more openings.

John Laforme: 1:02:42

So it's it's a second, it's just a little bit destructive there. Depending on how the house is built

Abe Simantob: 1:02:48

these topic that we're talking about today. We can talk about this for like eight hours for record toolbox or something. We haven't really covered a lot of stuff, you know, like you go to some houses, John, they have really leveled it. Yeah, you know, the house has settling issues, and they come and jack up the house. And they put a layer of cement or shimming plates on top of the stem wall and you think, Oh, the floor is fine. They again, they didn't address the mechanism that caused the original settling. All they did was temporary the level it bandaid. Exactly. So we have to be careful out there. Real estate is not cheap anymore.

John Laforme: 1:03:31

Now, not in this town, or any town next to it for that matter. It's absolutely bananas. But uh yeah, my my last, my last takeaway for this episode is to better educate people. So that's what that's why I do this podcast,

Abe Simantob: 1:03:48

bolting cripple walls, you know, in a word, the floor, where you walk on, sometimes there's a wooden wall that goes between the floor framing to the top of the concrete stem wall, we refer to that as a cripple wall. Yep. Nowadays, we are supposed to reinforce that wall with a sheet of plywood. So, building doesn't wobble too much in America. A lot of houses don't have those.

John Laforme: 1:04:11

Right? That's true. So what I want to just end the episode with is if you're a new home buyer, and you're looking at a house on a on a hillside or you know, don't be afraid of it, just just get all the facts. And that's that's what inspection contingency period is for calling in someone like myself or someone like AEV to let you know what's going on with the house and as he mentioned he can do some history and look up some history on the house. If there is history, he's gonna he may be able to find it, which is really going to help and improve his his assessment. Yeah, his assessment of the of the property. And as for home inspectors, if if this is something you're not familiar with yet, or you haven't had to experience yet, it's pretty important stuff. You don't want to overlook this. You don't want to ignore it. Just I didn't pay attention to that that day. Well guess what, you get a phone call later on, hey, why didn't you tell me this house didn't have good drainage on it or any drainage period or whatever. So, if you're a new home inspector, this is extremely important to understand the importance of drainage and my advice to any home inspector, if you are doing a home that is on a hillside or you have any idea at the at the lot was on a cut fail if somebody told you or if the house if somebody discloses it has liquefaction and if or if you notice expansive soil, you need to recommend a geo geotechnical engineer. I do it every day. Because I just want to let my clients know and I don't want them thinking I ignored something. So that's it. Thank you a reach here, where can they reach you?

Abe Simantob: 1:05:56

Thanks so much for having me. My website is very easy to remember. Geo-engineer.com Alright, we ever want to look up you know, somebody to do an inspection, they just search with geotechnical inspection, and my companies usually pops number

John Laforme: 1:06:14

one. Okay, right. And once again, as I always mentioned, I do have a YouTube channel. We did record this or YouTube as well. So as soon as I get the YouTube video edited and uploaded, I will add a link into the podcast description. Thanks, everybody for listening and thank you very much. Have a good one.