I am planning to insulate the existing concrete floor of my woodshop. Major manufacturers of polystyrene insulation indicate the sheets are non-compressable and 2-by sleepers are not necessary when two layers of 3/4 plywood are added as the top floor. This seems to fly in the face of reason and my question is – has anyone installed poly insulation on a floor without using sleepers ?
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Replies
Sleeper
No Put down 1 layer rigid foam tape all seams with tyvek tape then 1 layer plywood. Use tapcone screws to hold down plywood then you are done.
Who you gonna believe?
The manufacturer or a bunch of 12 year old girls you met on the internet?
Type II EPS is the lightest available and it will hold up a concrete slab.
If you stagger the joints the point loads will be spread, unless your shop is full of 4 ton lates and such.
Glue and screw the ply together and you basically have a sheet the size of your shop.
I'd use EPS, it's cheaper and treated with borate so bugs don't eat it.
Joe H
Foam insulation is rated
for load. Around here the usual material for underslab use is Foamular 250, which is good to 25 PSI, but they make a 500 and a 1000 for heavier use. If you are talking to the manufacturers I would ask them which of their products are appropriate for your use. If it were me, and the dryness of the existing slab was not known, I would lay down 6 mil poly first, then a layer of foam insulation, then the plywood. The shop floor may seem dry now but it is exposed to the warm interior air. Cover it with insulation and things may change.
http://insulation.owenscorning.com/professionals/insulation-products/applications/under-slab.aspx
No sleepers required. extruded polystyrene is often used for many applications where a load is distributed over it .... roofs, slabs are the most common. As long as you have your fasteners for the flooring figured out, it shouldn't be an issue. That is the most common reason for sleepers ... something to attach your fasteners to.