I have a question, to which I’ve received varied answers. I’ll be excavating for an addition to my home, and it seems a shame to simply fill around the footers under my single stall attached garage with sand and placing a slab. I’d like to take advantage of the potential basement space beneath it, by using some galvanized or such form (like on bridge decks) and placing the slab on it, with an open basement beneath. The most common answers I get is that it can’t shouldn’t be done from practical and cost standpoints.
Has anyone installed such a basement, with a slab above for a garage? If so, where did you get the steel forms / trays to support the concrete until it set? Any perspective on cost would be appreciated.
Thanks.
Replies
I dont know much about the subject but when I was looking around for ICF's I found a product you could use at http://www.polysteel.com/paneldeck.html. Its a foam system with built in steel beams that can clear span 40 feet (so they say) then your pour your slab on top.
My neighbors did the same thing your talking about when they built their house. They hav a full basement under their garage. They used Span-crete then poured about six more inches on top of that(I think six).
Like I said I dont know much about the subject just wanted to share what I have seen.
M. Anderson
Other than cost, there's not a reason why not. Both the products already recommended will probably work fine, you also might check into C-Deck from Reward Wall Systems, and Hambro trusses.
Hambro is a steel truss system that puts the top chord inside the slab. Mechanicals can be run through the space below, downstairs ceiling attaches to the bottom chord.
Newk
This is perfectly feasible, you'll need an engineer to design the slab, rebar, support beams, etc., for you and there are rental centers that will rent you the steel formwork pans --- and the support system if you wish.
I have a basement done like that. My was done 20 years ago and they used plywood sheets supported with bar joist. In the last couple of years I have seen a couple of additions that where done with similar technics.
I use my for a shop and heat it. It is hard to insulate the ceiling so if I where doing it now I would investigate the ICF's. There are a couple of companies that have them for this type of application.
In some parts of the country it is common to use precast connect slabs instead.
I just did a house with a slab over the basement. We used a foam form call Lite-Deck. It was very user friendly and went in for about $10/sq ft.
They have a web site that will help you engineer your spans and rebar schedule. We poured 4" with 10"x6" 'joists' every 2 feet. I was impressed with the system.
KimballKimball
I think spancrete is the only way to go. It's possible to do it with specially engineered wood web floor trusses. But no one has ever bought them after I've priced a job out...........(-:
Truss Designer Extraordinaire