Suspended Concrete Floors?

[cdhd2001]

Has anyone built a suspended concrete floor for a workshop before?

I am prepping for a 12 ft x 24 ft tool shed. Because of the creek and floodplain, the floor will need to be about 3 ft above the ground. My original thoughts were to build a wood floor. But, since I do alot of welding I decided I don't want a combustible floor.

The building will be all steel pole building style with 3'' pipe and C-purlin construction. The floor would be supported by vertical 3'' pipe on 6 ft centers and floor joists of 8'' purlin on 24'' centers. If I do a concrete floor, my thoughts are to install 26 guage R-panel galvalume to the top of the 8'' purlins and ring it with 4'' purlins. This would allow for a 4'' thick concrete slab with #3 rebar at 18'' centers. I am also thinking of dividing the floor with additional 4'' perlins at 3 ft centers (divide the concrete into four 3 ft x 12 ft sections). The extra 4'' purlin would give me additional attachment points for equipment.

Any thoughts or suggestions?

 

[wedge40]

Move?
Wedge

 

[Egon]

You may want to check out precast floor sections that are designed for the proper load.

 

[cdhd2001]

You may want to check out precast floor sections that are designed for the proper load.

Any links?

 

[Egon]

For that you would have to check in with some of the local Concrete suppliers. They may have some standard sizes they have forms for.

 

[westcliffe01]

The footings will still need to be below ground level, right ? Moving around in 3ft of vertical space is a pain in the A---. But it it was 6ft it would be pretty easy. You could get yourself whatever type of shoring you could find to support the weight of the deck (I would say you need 6" minimum with proper reinforcing). Build up the perimeter wall to the right height on the footings, providing a place to get in underneath to set and remove the shoring. It should be possible to use 3/4" OSB for the formwork. Lay a vapor barrier over it to prevent the concrete adhering to the OSB. Set up the re-inforcing on top of the vapor barrier (raised to the right height of at least an inch off the formwork and using wire chairs to stop it moving when doing the concrete work)

It should be possible to hire scaffold to support the formwork. This means that only the OSB would have to be bought for the formwork. Put scaffold planking on top on which the OSB is laid. This makes for a nice uniformly distributed load. Use adjustable feet on the scaffold to get the floor leveled perfectly. When the concrete has been poured and has set long enough, lower the support deck using the adjustable feet, dismantle and get all that stuff out there.

Depending on the size of the floor, it may be neccersary to create concrete beams to carry some of the load. This requires "channels" in the otherwise flat formwork and complicates the shoring a bit more, but not unmanageably. This type of floor would normally require an engineers approval unless you are not in a zoned area. Even then, its probably a good idea to follow guidelines since you want to get it right the first time. The process is obviously labor intensive and hiring the scaffold is a real expense, but the kind of floor you get is simply the best.

 

[MikeD74T]

Has anyone built a suspended concrete floor for a workshop before? Any thoughts or suggestions?

Ask your library if they can get you a copy of "Architechual Graphic Standards". It has charts for spans/slab thickness/ etc. Your project is very doable and common in commercial construction. If you have a precast supplier within 50 miles you may find cut off damaged /rejected pieces that will fill your needs for reasonable prices. MikeD74T

 

[tommu56]

we had lofts at work made with this type of pannel

Bryce Saylor & Sons Inc

another one

Precast / Prestressed Products: Hollowcore

google precast concrete floors and your local area,]

tom

 

[Ranger Rick]

I have a neighbor that built a new house with Styrofoam forms for both the basement walls and the first floor. He put radiant heat in the concrete first floor and the Styrofoam forms insulated the bottom of the floor as well as supporting the concrete. I believe that he used the litedeck system for his forms About Lite-Deck ICF Floor, Roof, Deck and Walls!
It was pretty interesting to see it all going in.
Rick

 

[gpflepsen]

With a raised floor above grade only 3', I would fill with compacted dirt and pour a slab on grade floor. It would probably be much chaepr than putting in an engineed structural concrete floor. 3'x12'x24' is only 32 yards of fill, or about 4 truck loads.