# pros and cons of slab vs. crawl space



## DQ (Aug 4, 2006)

most of the new homes being built around here are on a slab. older homes are all built with a crawl space. I am putting together plans for a small building as much for use, as for "practice" building a substantial structure. I keep coming back to the idea that I would prefer to have a building with a crawl space. it seems much less daunting as far as actual construction because I can do a bit at a time, it seems it would be easier to plumb and run electric both as far as planning and construction as well as offering the option to alter utility lines later if need be withoutout jackhammering concrete out (aka... if I screw up the first time). I also would not have to pay for the concrete and pro finishers and feel I could confidently plan and construct it myself. (keep in mind this is all in practice for a future larger scale project (home) not just easiest ways to build a small building.)

what are the real advantages of a slab foundation that makes them used more often (currently)?


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## michiganfarmer (Oct 15, 2005)

I wouldnt want either one. 

I want a basement. I want the extra space, and someplace underground incase we ever get a tornado. Also Ive heard an unfinished basement is the least expensive space in a house.

If I lived in tornado alley, I wouldnt have a house above ground


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## cfabe (Feb 27, 2005)

In more southern areas like where the poster is from (oklahoma) Basements aren't as popular because you don't have the deep frostline. Up north if you're going to have to dig down 3-4 feet anyway it's a lot less of a jump to put in a basement. 

Between a crawl and a slab, you're right a crawl will make it easier to work on in the future. A friend who had a slab in part of their split-level house had to replace a drain line under the slab which required a lot of dusty cement breaking in the house, and of course replacing the floor coverings after it was fixed. 

The floor also feels nicer with a crawl space, it's not as cold as a slab and isn't as hard to walk on. Wood floors have some give which cushion your feet, this is particularly noticable if you've ever walked on a slab without shoes. One downside to a crawlspace is that it must be maintained, if you are in a wet area you'll need to check periodically to ensure there's no water/moisture in it and take care of it if necessary (sump pumps, drain tile etc). Also make sure no pests are making their home there. Slab houses don't have those problems. 

Crawl space houses also usually sit up a little higher off the ground which I think makes them look nicer than a slab house right on the ground. But that may be just because I'm used to it. Not many slab houses around here.


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## NEOhioSmiths (Sep 28, 2007)

I agree with michiganfarmer - go with a basement. You'll be much happier in the long run and won't notice any cost difference a few years after the house is completed. I'll go even further and say if you're going to do a basement, consider (1) poured walls, (2) an extra course of two of block if you going that route, and (3) make it a full basement. Basement is such useful space - root cellar, workshop space, workout space, storage, safety, .... Once you have one, you'll never want to be without one.


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## mandidawn (Aug 11, 2006)

I'm on a crawl-space, and I like it. Wish I had a basement, but whatever, next house.

Make sure that your crawl-space is high enough to be comfortable to crawl in. So many are not, and a larger person either has a very hard time getting in there, or just cannot at all.

Insulate really good under there. So much air is sucked down that the floors are really cold in winter (that's what I plan to do this long weekend, hang out with the spiders under my house insulating).

Lastly, make sure you close up any holes coming into the house (for pipes and such) really good - mice hang out in the crawl space, don't let them hang out in your house.

Good luck


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## stranger (Feb 24, 2008)

NEOhioSmiths said:


> I agree with michiganfarmer - go with a basement. You'll be much happier in the long run and won't notice any cost difference a few years after the house is completed. I'll go even further and say if you're going to do a basement, consider (1) poured walls, (2) an extra course of two of block if you going that route, and (3) make it a full basement. Basement is such useful space - root cellar, workshop space, workout space, storage, safety, .... Once you have one, you'll never want to be without one.


 go with the basement, sink it right down about 10 ft. sleep in it in the summer, it's built in airconditioning, plus all of the above


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## mnn2501 (Apr 2, 2008)

DQ said:


> what are the real advantages of a slab foundation that makes them used more often (currently)?


They're cheap thats the only advantage. in OK as well as any other warm place Pier and beam in the only way to go. More expensive but you won't have to have your foundation fixed or worry about the foundation moving and your pipes breaking. A slab will shift with time in the south - period,
Crawl spaces attract critters and can cause freezing pipes if not insulated properly -- they also make for warm floors in the summer and cold floors in the winter.

Basements are not really an option in the south, they're way too expensive due to the heat and the drying and shifting ground. They need to be re-enforced and the surrounding ground needs to be specially prepared, a basement in the south will cost 3 times what a same size basement in the north will cost.

I love basements having grown up in MN, but living in TX theres no way I'd put out the money for one.


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## OntarioMan (Feb 11, 2007)

I'm sure slabs have many advantages :

- fairly easy install of hot water radiant heat
- concrete is fairly inexpensive
- concrete is quick to install
- not having a basement or crawl space means the building is higher, less chance of flooding
- concrete is fireproof and strong
- concrete may be more insect resistant
- concrete represents lots of "thermal mass"

I have a basement, but I certainly would not rule out having a house in the future which was on a slab - I suppose it would all depend on the site specifics and economics. I know of a house on a flood plain which has a basement, obviously not a wise idea. Why was the house built with a basement? Probably because whoever built it ignored the site specifics, and had always built houses with basements.

.


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## tiogacounty (Oct 27, 2005)

I build in an unusually wet area of the mountains here in NE PA. My choice is a conditioned crawl space. This is a 4' tall, 8" thick poured concrete wall on a 8"x20" footer. First the floor area is filled with 3/4 clean stone to the top of the footer level, then a "rat slab" which is a 3" thick, roughly troweled slab is installed over 6 mil poly. There are NO vents and NO insulation in the floor joist. The walls are sprayed with R-10 urethane, from the rat slab to the plywood subfloor. The HVAC ductwork allows a small amount of heated and cooled air into the space. This sealed crawl is clean, well lit and dry as a ghost fart. I have had realtors, with decades of experience in the area, tell me it's the nicest crawl space they ever have seen. If your wondering why go to all this trouble and not just put a basement in? The answer is simple. I have been able to monitor the ground water level of the latest house I built, as it has a vertical dry well a few feet from the foundation wall. The static level of the ground water is the bottom of the footer +/- a few inches depending on when it rained last. So, a full basement would be located in 4' of standing water. Not an impossible problem to overcome, but why look for trouble? Google "conditioned crawl space" for more info. Good luck.


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## michiganfarmer (Oct 15, 2005)

mandidawn said:


> I'm on a crawl-space, and I like it. Wish I had a basement, but whatever, next house.


Jack your house up, dig the crawl out to 8 feet deep, pour new footers, lay new block walls up to your bottom plates. 

voila, a basement.

I did it. . I dug it out by hand. I dug the footers by hand. I hauled the concrete for the footers in by hand in 5 gallon buckets. I hauled the block and morter in by hand. 

It sucked, but i have a basement


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## mnn2501 (Apr 2, 2008)

michiganfarmer said:


> Jack your house up, dig the crawl out to 8 feet deep, pour new footers, lay new block walls up to your bottom plates.
> 
> voila, a basement.
> 
> I did it


 Michigan is MUCH different that OK or TX -- it won't work here. There is a valid reason why almost no one has basements in the South


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## michiganfarmer (Oct 15, 2005)

mnn2501 said:


> Basements are not really an option in the south, they're way too expensive due to the heat and the drying and shifting ground. They need to be re-enforced and the surrounding ground needs to be specially prepared, a basement in the south will cost 3 times what a same size basement in the north will cost.
> 
> .


really? thats interesting. I dont understand how the ground shifts. How does the heat have anything to do with the cost of a basement? 

My inlaws in coastal NC say the water table is to high there.


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## michiganfarmer (Oct 15, 2005)

mnn2501 said:


> Michigan is MUCH different that OK or TX -- it won't work here. There is a valid reason why almost no one has basements in the South


they person that I was telling that to is in Michigan. 

I thought so anyway. I will go back and look to make sure.


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## vicker (Jul 11, 2003)

mnn2501 said:


> Michigan is MUCH different that OK or TX -- it won't work here. There is a valid reason why almost no one has basements in the South


You forgot to post the reason.  The south has less drainage problems than up north. They just went a different route in house building.
Used to be people in the south built above ground with no under pinning for cooling purposes. Nothing sucks worse than working under a crawl space house that is only inches above ground. If you go that route, make the lowest point no lower than 2 feet (and that ain't high enough).
Concrete slabs are the cheapest route. That is the only benefit. Standing on concrete is murder on your feet, leg, hip joints. The floor is cold. They crack and settle. Go with a dirt floor first.


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## mamita (May 19, 2008)

my brother in TX couldn't build a basement due to massive boulders, so it is on a slab. it just wasn't feasible, so I think it would depend on your land. I never noticed a difference walking around inside, maybe cause it's warmer than my house in the north. we have a crawl space, and it is better when you change plumbing and such. we've never had water issues, but do have the small vents screened with metal lath to prevent unwanted guests. we do hope to one day dig it out, cause the storage would be wonderful. guess it depends on your budget, your ambition, and your property. happy building!


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## CGUARDSMAN (Dec 28, 2006)

Not many basements here and the ones that have them they are usually walkout. We have a crawl space that is 6' just below the gravel is shelf rock which is why we don't have a basement. The Ozarks is all limestone so if a basement is gonna be built it requires lots of jack hammering and a geological survey to make sure there are no caves below the build site.


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## Quint (Nov 12, 2004)

I went with a basement. It didn't cost all that much more than a crawlspace in the scheme of things.

I've never heard anyone build a house with a basement say "I like my house but I wish I hadn't put a basement under it."


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## Marsh (Apr 29, 2003)

We have both. Our house is a crawl space and the apartment is on a slab. They are both sitting ontop of HUGE SLAB of ledge. When they were built there was no way to get through the rock so they built ontop of it. We could now some 60 years later have the house jacked up or moved and the rock removed because methods have changed. But honestly the expense would be cheaper to build another house somewhere else.
Let me tell you that the house being 2 stories high and only 2 cement blocks for a foundation. Shifts all the time. The house was built in the 50's and sometimes the frost heaves make the house go one way or the other, meaning, yes, the house floats at times. Not alot but some.  I am sure newer methods of crawl spaces stop this. 
Our apartment unit is on a slab and it has no real problems at all. All the plumbing and wiring were put in from the attic. So it comes in from above not below. Much easier to get to and much easier to find a leak if there are any. No crawling in with the creepies hoping the house don't fall on you LOL The floors are just as cold in winter with the slab as the crawl space. The only difference is you could use and outside woodstove to heat radiant floors in the slab if you want. I suppose you could also do this with a crawl space. Also you can also lay alot of different flooring on a slab than you can a crawl space. The crawl space houses tend to float alittle and not all floor coverings will float with the house. Such as hardwood floor. I was told it would crack and just not be worth it due to the float factor. 
I also think with a crawl space you might be limited on the weight the house can hold. I know ours doesn't have too many pillars under it. It is more of a foundation ouline. It does have some carrying beams to hold the weight. 
I also know that with a crawl space the air gets underneath them and if it gets damp you can risk the floors rotting out. But then again if they do you can gain easier access from above to cut out and replace. 
The toilet here once had issues and the old owner couldn't fit unneath the house so he went from above to get at the problem. Now we have a floor bolted around the toilet. So if you ever have a problem again you can access it by unbolting the floor. LOL 
Hey we might not be in the best situation with the house but I have to admit it gives the house character and we like it. 
If we ever move to another house I suppose we would have a basement. But in living in this one. There is no basement and no attic. It has taught me how to live with less. You never realize how much "stuff" you have in your attic and basement until you go to move and don't have either. LOL 
On a last note. You might check with insurance companies. I know it was hard to get insurance on the house with a crawl space because they are considered high risk. The apartment was very easy to get insurance on the slab was no big deal. We ended up getting farm insurance because the insurance company didn't like our monitor heating in either place. They said it wasn't a consistent source of heat. I refered them to the woodstove and that wasn't consistent either. I refered them to the door and found a farming insurance that didn't mind any of the above ROFL 

Sorry this is so long. Just hard to explain in few words the things we see with slab and crawl space. 

Marsh


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## DQ (Aug 4, 2006)

I suspected that one of the only advantages of the slab was cost. my inlaws house had to have major foundation work done on their slab. my current home is on a slab and we totally rigged the washing machine to move it out of the middle of the kitchen to avoid hammering out the drain and moving it. I kept remembering in the house I grew up in, and a trailer I lived in, the hardest part about moving or repairing the plumbing was getting down and dirty and feeling like you had spiders crawling on you the rest of the day..

I have always had major basement envy. I have been told many times though that they are not appropriate for our area. I have thought about (eventually) building a house "in" a hill to to take advantage of the cooling effect as well as the safety (I am in major tornado alley, NE oklahoma). I could build my "practice building" in the same fashion on a small scale. my inital thought is to essentially build a retaining wall with block, with plenty of dead men, drainage and moisture barrier and than push the top of the hill down against it. there are obviously some serious details to work out but in a nutshell would that work??????


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## ChristyACB (Apr 10, 2008)

Crawlspace here. Mine is 3 feet for a 4 foot raise at the floor due to A4 flooding zone. I love it. So much less hard than a slab and so easy to get to stuff when it goes wrong.

That said, I have to echo what others have said. There is much more maintenance with a crawlspace and the bigger the crawlspace, the more maintenance. In my case, it is big enough to work very comfortably in, but it has drastic changes in temp and enough room to be comfortable for invaders. 

Wrap pipes, seal the accesses to the house around pipes repeatedly because they can wear, insure you get the very upgraded vents that shift in relation to the need rather than static ones and put extra insulation and a vapor barrier under the floor. 

Another consideration is the flooring. If you are getting a wood floor, be sure to pay a little more for a very thermally stable one. It will make a difference. 

As to basements, so far nowhere I've lived in VA or NC was that even possible. The water table here is just too danged high and drainage issues are significant. Can't even have in ground pools around here or where I came from in NC without massive and excessive work or else they slump inward.


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## Nevada (Sep 9, 2004)

The post foundation is, by far, the least expensive option. It's also the easiest to be a complete DIY project.

I looked into doing a concrete slab and it was going to be several times more than the post foundation, even if I mixed my own concrete.

The basement is the most expensive option, of course. You still need a concrete slab and a sturdy sub-floor, costing as much as a post and slab foundation combined, then you also need to build waterproof concrete block walls and pay for excavation.


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## 65284 (Sep 17, 2003)

A very good solution to this problem is to design the house so all of the plumbing is in a line and build a service tunnel. The tunnel is 36-48 inches below floor grade, and 36 inches wide, (think concrete trench or micro-mini basement), with an access trap door someplace. 

A trench is dug, the floor and walls of it are poured, the "roof" of the tunnel is formed when the floor slab is poured. All of the plumbing lines are sleeved and go through the slab directly into the tunnel and run at right angles along the top of it, just below the floor level. It's also easy to it wire for lights at this time. 

This costs a little more, but is well worth it if you ever have any plumbing problems. As an overall percentage of the cost of a house the outlay is very, very small.

If you are ever faced with the expense, noise, dust, and disruption to your life caused by removing a slab floor, or being forced to run water lines overhead, a service tunnel will seem incredibly cheap. Believe me, I know from first hand experience!! 

Everything is easily accessible, with room to do repairs. The usual problems associated with in slab plumbing or crawl spaces are avoided. It also makes a good place for stashing valuables or for a short time emergency shelter.


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## SunRiverMan (May 22, 2008)

I have a basement now and I had a crawl space on my last house. I prefer the crawl space.

My crawl space was 5' high. I cleaned it out and used it for storing those things that fill up a garage or shed. The best part is that the crawl space made a great root cellar. One day I cleaned the cobwebs, installed lights, and put down large rolls of plastic over the dirt.

I had all kinds of food storage and nobody never knew it was there. I prefer the crawl space. My entrance door was from a hall closet that the vacuum cleaner sat on making it not noticeable at all. SRM out!


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## MariaAZ (Jun 5, 2007)

michiganfarmer said:


> I dont understand how the ground shifts.


I don't know if our situation is the same, but we have something called "expansive soil" in some areas. When the soil gets wet, it swells, and when it dries out it contracts. This expanding and contracting can cause buckling, which can wreak havok on slabs, sidewalks; pretty much anything that depends on the ground to remain in one place.


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## michiganfarmer (Oct 15, 2005)

SunRiverMan said:


> I have a basement now and I had a crawl space on my last house. I prefer the crawl space.
> 
> My crawl space was 5' high. I cleaned it out and used it for storing those things that fill up a garage or shed. The best part is that the crawl space made a great root cellar. One day I cleaned the cobwebs, installed lights, and put down large rolls of plastic over the dirt.
> 
> I had all kinds of food storage and nobody never knew it was there. I prefer the crawl space. My entrance door was from a hall closet that the vacuum cleaner sat on making it not noticeable at all. SRM out!


why do you preferr that instead of the basement?


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## hotzcatz (Oct 16, 2007)

Nobody has basements around here, not exactly sure why. Some "crawlspaces" have ten foot ceilings in them, though.  Houses up on post and pier foundations have much better ventilation and a lot less centipedes.

Our house is built on a slope and it's not quite forty feet long. The back end is one foot above grade and the front was eight feet above grade although two feet of that was from erosion from the eves dripping down and washing the dirt away. (The house has been here almost 100 years). We dug out under the house so it has eight foot headroom about three quarters of the way back and then steps up to five and a half foot headroom for the last eight feet. It is still up on post and pier though, so it is more of an under house carport than basement. Fortunately we were able to use a garden cart to move the dirt with instead of a five gallon bucket. That was real handy to level the yard with so now we actually have flat spots to garden in.


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## clovis (May 13, 2002)

Resale value is the biggest reason you might want a crawl space over a slab.

Homes around here, at least by my experience, sell better and have a higher resale value if they sit on a crawl.

In our area, nearly all the 'cheap' homes that are sold in sub-divisions are sitting on slabs, while custom homes sit on crawls.

30-40 years ago, a sub-division was built in our town. All of the homes were built on slabs. I have seen alot of these homes, and you would not believe some of the cracks that I have seen over time.

Personally, I would not consider buying a home built on a slab. It tells me that someone, somewhere, for some reason was trying to save time or money. It makes me wonder what else they tried to save money on, like framing 48" on center, LOL.

My inlaws have a slab built home that is 44 years old. They have had expensive repairs to sewer, plumbing, and heat because of the slab.

My cousin built a home on a crawl, and added one extra course to his block, as well as wiring and lighting it. Talk about a nice crawl to work in!!!!! Definately something to consider!!!!

Clove


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## OntarioMan (Feb 11, 2007)

I think folks have to put the misconceptions aside and look at each individual build as a "unique" situation. Because someones neighbor, brother of a friend of a cousin in Toledo had a poorly designed/constructed slab foundation really means nothing. I've seen basement walls buckled 20 inches in and crawlspace foundation walls which basically collapsed - all means nothing.

When you look at it logically, most basements are just slabs placed in the ground instead of on the ground. Basements are indeed a very good value when it comes to square foot vs. cost, but they're not without thier own problems. As mentioned above, I have a basement, but I'd have absolutely no problem buying or building a house on a slab - if a slab was a valid design choice (and properly designed/constructed).

Take "rubble trench" foundations for example - I'm not even sure I could get this type of foundation approved here - but it may be a very valid and cost effective design choice. 

Every foundation type will no doubt have many advantages and perhaps many disadvantages. Which one is the "best" choice for your situation?

.


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## clovis (May 13, 2002)

OntarioMan said:


> I think folks have to put the misconceptions aside and look at each individual build as a "unique" situation. Because someones neighbor, brother of a friend of a cousin in Toledo had a poorly designed/constructed slab foundation really means nothing. I've seen basement walls buckled 20 inches in and crawlspace foundation walls which basically collapsed - all means nothing.
> 
> 
> .


I figured I would take a beating from someone over my post.


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## homebirtha (Feb 19, 2004)

Our house is on a crawl space. We're doing an addition and it's going on a raised slab. We made that decision for a few reasons. 

The floors over the crawl space are COLD in the winter. Much colder then the air above. We can have a good fire going in the woodstove, 78 degrees 3 feet up, and the floor is freezing cold. Also, we get critters under there frequently. It sucks to have to crawl under the house to take care of pipes or wire. The pipes have frozen a few times under there. 

So in the addition, we're doing a raised slab. Block walls up about 24" above grade, fill and tamp inside, then pour a 5" slab inside the walls. We're doing radiant floor heat so no more cold floors!! WOOHOO! We liked the raised slab because of thermal mass. We're designing it with passive solar, so that slab will get lots of winter sun to warm it up and keep the house warm all day. We are also using the concrete as our finished floor, so we saved a lot on lumber for subfloors and it came out to be about the same cost, even with the extra engineering to make it a raised slab. Our plumbing is going through the ceiling and down the shared wall to the slab (still have to figure out better insulation so that they don't freeze). 

There are some really great products to finish concrete, staining, etching, polish, that make incredible looking finished floors. We may cover some areas with cork if we find the hard floors to uncomfortable for walking. I would definitely cover it with something softer in areas where you stand a lot, like a kitchen. Our kitchen is in the old section, so not an issue for us. 

I really like the idea of a concrete slab. It's much more energy-efficient then a crawl space, and that was a big motivator for us. 

Oh, and a basement was out of the question here, because of a high water table.


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## Jolly (Jan 8, 2004)

My house sits on a slab, and I wish it didn't.

Down here, basements are not the way to go. With heavy clay soils that expand and contract with the season, slabs are routinely heaved and cracked, so you can guess what would happen to a basement wall. Not to mention the high water table...I can dig a 48" posthole in the wintertime, come back and check it the next day, and find a foot of water in it.

If I had it to do over again...crawlspace. And it's not a cost factor. When you figure up the price of piers, joists and plywood for the floors vs concrete slab, it's pretty much a wash. If a house shifts when sitting on piers, it's a simple and inexpensive job to jack up and align. Check out the cost for stabilizing a slab and repair...


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## texican (Oct 4, 2003)

We call basements, in this part of the country, indoor swimming pools... The water table sometimes gets just several feet below the surface.

I'm building my home on a slab. For tornado fun, I've got a walk out basement half built... home built on a hillside... so the basement won't be 'underground' as far as the water tables concerned...


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