gypcrete and floor truss loading

Plumdog_2

I see in my Maxxon Brochure (several different types of poured floor leveling, sound proofing, fire-proofing and thermal applications) the Therma-floor weighs in at 12lbs/sq.ft when applied at 1.25 inch thickness,or about 115 lbs per cubic foot. Gyp-crete is listed at about the same. I was curious to know because I recently worked a project where one of the radiant panels was 3 inch regular concrete poured over what I think were 16 inch TGI on 16 in. centers with 3/4 ply subfloor; about 24x30 feet.

michael terry

gypcrete floor truss loading

would anyone know how many pounds per square foot you would figure for gypcrete with tile flooring , I need this figure for floor truss design.
thanks
Mike Terry

Brad White_78

Lightweight concrete

I imagine Gypcrete falls in the lightweight category, conventional concrete being 140-150 PCF with "lightweight" concretes at 110-115 PCF. To be sure I would get manufacturers data and consider the wet weight versus the dried weight.

Now to thickness, something only you would know: if say 110 PCF and 3 inches (0.25 of a foot) thick the weight would be 110 x 0.25 or 27.5 PSF.

(By comparison if all standard weight concrete, three inches would be 37.5 PSF).

Your thickness may well be less.

I usually figure tile and cement underlayment at the same density as standard concrete or stone. Often it is less but there is enough variation and the total when on a PSF basis for a thin layer is relatively minor. Say an inch of finish material (generous) at 140 PCF, 1/12th of that would be just under 12 PSF so my total with LW concrete and tile finish would be under 40 PSF dead load added.

Just keep your thickness in mind, get manufacturers wet data where you can, keep your deflections low (1:360 or better as may be recommended) and your pours small.

Paul Pollets

Gyp

13-14 lbs per SF @ 11/2" depth.

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