I just moved to Texas from Maine the houses I built in Maine were on a foundations with a floor system. Now I live in Texas and everything I have built for houses are built right on slabs. I am wondering why that is and what the benefits of each are.
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Replies
The main difference is that the foundations in Maine need to go below the frost line, which isn't an issue in Texas. Since you don't have to worry about freezing ground, a slab-on-grade is much less expensive to build and it acts as a heat sink to help keep the house cool in during the summer.
Here in florida, 99% of the houses are slab-on-grade for the reasons stated above, but also the water table is so high here, and kind of basement would quickly turn into an indoor swimming pool.
Andy
HammerMan
I just moved here from Iowa and am used to basements to, but have you went out and tried to dig a hole, try it, you'll see why the slab is necessary.
Texas is a big rock with a little dirt on top of it, I'm sure someone will disagree with me but I haven't seen any places where you can dig a foundation. You can build a walk out if you build on a side hill, depending on what part of Texas your in a side hill may be as hard to find as a basement.
Doug
I've built a handfull of slab homes on unstable ground, if done correctly it is a nice way to go, besides the problems you have with mechanical systems and flooring of course :) If the draintile isn't done correctly, expect problems in the future, I've repaired a few very old slab on grade homes, built in the 50's, poor drainage, cracked, sunk, and washed the fines out of the gravel beneath the slab. We stripped out the flooring and slab-jacked (mud jacked) the house back to level (or close to) then provided new draintile around the slab.
Welcome to Texas and the forum. Where are you? One of the minor issues that tends to irritate me just a little is that so many of the contributiors here have never seen a slab foundation, and their answers reflect that. They think all houses are built on some type of basement or crawlspace. And many have no concept of whole-house a/c. Grace ice shield...what for? Blueboard...never seen it. Frost depth...about a half inch. Don't get me wrong, it's just an interesting thing, these regional differences. People talk about renovating 200 YO houses...I don't think anything here is more than 75 yrs old (except my MIL, and she's as old as dirt).
Do it right, or do it twice.
No matter what the region is, the cheapest method is the most popular method. Try to differ from this, and the cost goes up. In our part of the country, northwestern South Carolina, both types of construction are used. My own house has a half basement, which is slab on grade. The other half is foundation walls with crawl space. Improperly installed slabs cause a great deal of trouble, and most builders do not care to take the extra precautions for a properly installed slab. Vapor barriers? Aggregate and sand subsurface? Cure protection? Never heard of it!!
The frost line is about a foot in this part of the country, and still perimeter under slab insulation is unheard of. Therefore, slab perimeters get very cold, vapor condenses on top of the slabs, and carpets mold. Then they can't figure out why.
The ACI has specific guidlines for slab installation, and they should be followed.
It's odd, for sure. Fifity years ago, here in central Texas, the only foundaion was pier-and-beam. Sometimes just blocks, too, no perimeter wall at all, other than a skirting of boards or lattice.
Soil conditions here are not the problem, either, you could have a basement just about anywhere in town, for only the effort in running a backhoe to dig it. This is not the case in Dallas, Austin, or San Antonio. (Austin & SA sometimes seen to have neagative soil depth :) .)
This can make for some odd slab-on-grade houses, too. Just north of Austin, in Williamson Co., I've seen floor slabs that were 8" above grade at one end, and most of 60" above grade at the other. With nifty loops of post-tensioning wire strung through them. Now, if they were not (mostly) spec-built by huge national companies, then they'd likely be built with at least a partail crawlspace.
So, it looks to be mostly habit, and a very shallow frost depth.
Also, that slab will only be a couple feet deep into the soil, and have at least an 8" exposure above grade. That does not provide a very good heat sink, and sometimes contributes to higher heat loads inside the house (although, exterior veneer face brick does a bit more along those lines).
I've seen floor slabs that were 8" above grade at one end, and most of 60" above grade at the other. Happens all the time in San Antonio, which is on the edge of the Hill Country and thus has few flat lots (especially on the north sid eof town, where most of the high dollar building happens). In fact, I have seen slabs that are mor ethan 60" exposed, up to about 8 ft. I don't understand why they don't do a split level house, or dig just a little and have a walkout basement. We do have vapor barriers, but slab insulation? Just pile the dirt higher.
Do it right, or do it twice.
Yeah, but then the big buildrs would not be able to use their stock plans, which do not include messy details like elevation changes. They'll put 70 gallon water tanks up in the attic, too, instead of using a partial crawlspace. Filling that void full of concrete is not the chaepest solution, either. (Doncha just love to see the plywood & formboard joints on the those 1/3 & 1/3 million mc mansion's slabs?)
Really, it's no goofier than when I see them bring fill so as to build a split level plan in my relatively flat area around here. (And then, take not provision for preventing foundation movement in these lovely alluvial soils . . . )
Personally, I like pier and beam, it's economical in material use, energy efficient (more so with some insulation on the foundation wall), and relatively stable in our local soils. Best part is that you get to have a wooden framed floor, which has character no concrete slab will ever have.Occupational hazard of my occupation not being around (sorry Bubba)
Cap
Outside of Austin, I think near Buda, Pulte homes are building some houses with a basement(really just a walkout) they are calling them basements and in all actually they are, but they are getting a premium for them, something like 40G's more(I believe thats what I heard).
I would like to either find a pier built home or build one, I to like the idea of the wood floors, you can do so much more with them, more so than the concrete.
(Doncha just love to see the plywood & formboard joints on the those 1/3 & 1/3 million mc mansion's slabs?)
That's funny, I noticed that right away when I moved here.
Doug
That's funny, I noticed that right away when I moved here
LoL!
Those 1 gallon box or buford hollies planted about 24" apart and only about 12" tall, sure fon't do much to cover 4' of exposed foundation . . .
My other 'favorite' is seeing the driveways that have to make that same transition . . . Occupational hazard of my occupation not being around (sorry Bubba)
---"you get to have a wooden framed floor, which has character no concrete slab will ever have."---
To each their own. I prefer a slab, properly prepared, compacted and tested.
Our house now has one part a basement that has a wooden floor above and the other slab and I like the slab part much better. Then, there is no accounting for taste, is there.:-)
The many pier and beam houses with a crawl space around here have moisture problems and pest problems like snakes, mice, rats, scorpions, black widows, wasps, etc. Even the best have squeaky floors.
I rather know that there is not anything under there, finding their way occassionally into the house, something that seems to happen even in the best kept crawl spaces.
Our new house will be on a slab.
Ruby I like the flexability of a conventional foundation and built my house with a 3.5 ft. high crawlspace but after living in it for 8 years all of sudden I have the spider invasion from h... with 1/2 of them being brown recluses. Something I learned the other day is that wasp spray doesn't hardly phase a spider.
ANDYSZ2
I MAY DISAGREE WITH WHAT YOUR SAYING BUT I WILL DEFEND TO THE DEATH YOUR RIGHT TO SAY IT.
Wherever they may be coming from, you may need to nuke the house with pest control bombs and use a powder bomb with insecticide powder behind cabinets, bookcases, in droors, etc. where the bombs miss them and for continued control when the bombs fade, for those that come visiting later.
A friend had a brown recluse bite on a leg two years ago and after several surgeries to clear the damage she has a big hole there and is still having trouble walking.
Be very careful of poisonous spiders. Their bite can be dangerous.
We too like the idea of being able to get to everything from below, the pipes, wires etc. but not that much for the possible disadvantages, to us. We will run most everything over the ceilings, where we can. Of course, some plumbing will have to be in the slab. That is why we won't use any other than the necessary stuff there, like any heating coils or such, to avoid compicating things. They would be nice if we didn't have a slab.
Since the floors will be all tile, a slab is best for that too.:-)
To each their own. I prefer a slab, properly prepared, compacted and tested.
LoL! Too true. I might prefer that kind of slab, if I could find one ;-) . . .
Half and half is probably the worst combo, too. The transition is never quite right (and likely will change elevation unpredictably).
My objection to slabs is the fact that they are unmoving, static, 'lifeless' to use a term figuratively. I like floors that queak the least little bit, doors that change the way they close seasonally, you know, "character" . . . Occupational hazard of my occupation not being around (sorry Bubba)
" I like floors that queak the least little bit, doors that change the way they close seasonally, you know, "character" . . ."
I have seen concrete floors that do that, but it called a defect, not character <G>.
BTW, my house is a little different. It is on a full foundation, but a slab floor (cold area). And my basement is above the house.
Edited 10/17/2003 9:02:23 AM ET by Bill Hartmann
And my basement is above the house. I think that's called an attic.Do it right, or do it twice.
Nope
It has 4 walls make of concrete and a building above it.
And my basement is above the house.
Now, that deserves a picture or two--oops, we can't upload pictures . . . Occupational hazard of my occupation not being around (sorry Bubba)
It is simple, he says with an evil grim.
It is above, as in Higher, not directly over.
The house is on a hillside.
The lowest level is the main living space and it is a slab floor. 1/2 story higher and uphill is the basement under the garage. Then another 1/2 story to the 2floor of the house and the bedroom. Then another 1/2 story to the garge which is level with the street.
It is above, as in Higher, not directly over.
I see nothing in the description which precludes a picture . . . :)
Sounds, cool, actually.Occupational hazard of my occupation not being around (sorry Bubba)
I'm a fan of pier and beam floors too. Good point on the reasons given but my my largest reason is parochial. I'm an electrician and pier and beam gives you a crawl space that makes wiring, rewiring, and most other mechanical work so very much easier.
It is also a boon in any location with a high water table, poor drainage or light flooding. I have seen houses that were perpetually damp because the water table was only a foot or so under the slab. Even with a poly sheet underneath and acrylic top seal the concrete continues to leach water. Other houses in the area, a more traditional piered design, were dry.
gives you a crawl space that makes wiring, rewiring, and most other mechanical work so very much easier.
LoL!! Reasons that speak to a remodeler's heart! Perhaps I have been in too many old buildings, and know how they change. And, that knowledge just doesn't "jibe" with mechanicals buried under (or in) a concrete slab.
Could just be I'm lazy, and hate driving a jackhammer, too . . . :-)Occupational hazard of my occupation not being around (sorry Bubba)
One more advantage of the crawl space is that you can store poatoes there all winter and they will not sprout, stay fresh. Of course, no one needs to buy and keep their potatoes safe for a year after harvest anymore. We are spoiled, can go buy what we want.
If you store them there, just go in there to get some when you need them, remembering to watch out for rattlers and spiders.;-)
Every place has there own best method. Around here wood floors are nice and there are some pier housing, but we are in the termite capital of the world so slabs are the best way. Its also quiet to walk on. But we also just scape the top soil. form with 2x4 (yes 2x4) dig a 10 inch trench for the footing and pour. Its real common to start one day and pour a day after. Because we have no winter its also a problem of all the animals getting under the house and nesting in the insulation. So for wood floors you get, termites, wild animals, mesh insulation, screw up plumbing, spiders and a two foot step to enter house. For slab you get, cold feet, and can walk right in.. Now I did mine by blocking a stem wall 2 course and fill with fill dirt with slab, so my elevation is about a foot about natural soil, which i slope to house. My yard slope toward house from the back so I raise elevation, also sepyic tank guy put the tank in too high.so I had to raise elevation.