Seen a few homes in Charleston sc with crawl spaces (say 3 ft high) where the “floor” of the space instead of dirt is cement/concrete.
How common?
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I don't know how common it is but I wish mine had cement instead of visqueen and dirt.
There was a builder in this city that was known for that (he poured a fairly thin floor) - and I happen to know at least a couple of owners of those houses. They really have enjoyed and benefitted from that.
Considering the problems of crawlspaces and the poor and "uncomfortable" efforts toward solving them (visqueen, gravel) and - on the other hand - the storage value and neatness of concrete (it's even brighter) - I think it's money you would never worry or have regrets about.
Out here, it's called a "rat slab".
It makes it a breeze to work under the house--use a mechanics creeper to get around.
Cliff
Thats what we call em here in Jawja too.
Rat slab out here in the land of latte as well.
Not always concrete though I have seen many done in CDF.
CDF... wassat?
I knew I was going to get asked that.
I should have asked someone to remind me today at work.
I was told many years ago now I forgot hang on let me google it & see if it jogs the memory.
It's like concrete but with either a 1/2 sack or maybe 1 sack of cement also called flowable fill. Comes out of the mixer truck.
AH here it is CDF = Controlled Density Fill 200 to 500 psi
http://www.cif.org/nominations/nom_156.html
Thanks now I know more about it than I ever wanted to. LOL
In pre-planning, my arkeetekt said the concrete was basically a watered down mix and would essentially self level itself. Contractor said pretty much the same thing but during the pour, it looked like the same old, same old to me. Then they bullfloated it and gave it a nice smooth surface. Don't know if it was something different after all but it worked out great!BTW, someone mentioned 24" from slab to joist bottom. In our area, code requires 28" minimum. Nice to actually be able to work under there!
Here the word "slurry" is used for that kind of high water/low cement fill mix. 200 - 500 PSI sounds about like a match for the adobe ground in my crawl space. ;-)
-- J.S.
Just finishing our new home and we poured a 2" thick slab in our crawl space. Architect called it a "dust slab" but I'm sure it's known by many differnt names. Unusual? Maybe but what a difference when you're working under there! You should see the faces of the contractors light up when I tell them too! Once finished, I figure the benefits are: cleaner space, less moisture and much nicer environment to change furnace filters. Also ties the walls and piers together making the whole foundation stronger IMHO. Go for it - I think it's worth the extra bucks.
I think in general a rat slab is a really good thing. Just consider those few small places where pipes and stuff have to go thru, and leave yourself a little bare dirt so you can dig and replace should it become necessary.
-- J.S.
Must be a regional thing. I've never seen a crawl space with a slab in it. Never even heard of one except on BT
Being blond is definitely a different state of mind. I can't really put my finger on it, but the artifice of being blond has some incredible sort of sexual connotation. [Madonna]
I'v seen houses (maybe forty years ago), that had concerete crawlspaces and the furnace just blew into them. Wherever they needed more heat or cooling, they just cut another register into the floor. Made for a very comfortable house, aand the crawl was verry nice to work in.
As a fellow latte land guy we do a lot of Rat slabs in the crawls. Have had some smooth and for some reason have had some that have been raked or rough (supposedly the rats don't like to walk on the rough surface?)
All I can say is if you go that way do the trades a favor and give it a quick trowel.
And what the heck just as a rant why doesn't everyone just agree to go 24" to the bottom of joist. 18 " just gives me a headache.
Actually Romero, I left what was destined to become latte land over 30 years ago. Can't say I regret the decision.Where I live now, we don't have a building dept. If you can satisfy the health dept.with your septic system, you're a go. Don't matter if you live in a shipping container. Don't get me wrong, where I build has some of the most stringent code requirements there are and I build everything to those specs. required or not. note the difference between where I build and where I live! We don't have rats here, I think the possums keep 'em down Jim
Ed:
I have seen a few slabs in crawls here in Michigan.
I just built a new home on a crawl space. I priced out a 2" slab. (4K for 2,100 s.f.)
I then saw in f.h.b. an article about the "cleanspace system". I can't tell you the issue right now, but you could search it. I ended up using the system. Intalled it myself for 1.2 K. It is awesum. It is radon proof (concrete is not), moisture proof (not concrete). I placed 4" of peastone underneath. I dropped 4 heat runs in my crawl, crack them slightly and my crawl is dry and comfy. No insects, mold, moisture.....nothing.
You can't roll around on a creeper, but it is clean, bright (white) and dry to crawl on. Mine has been down for a year and no problems.
Check out the article. Just food for thought.
nailer01