Shed Floor Insulation - Any Tips?

[Bob Bessette]

Hi All,
I live in the White Mountains of New Hampshire so around this time of year it gets pretty cold. Since last winter I have insulated my walls and ceiling of my workshop and am running a Rinnai propane heater every day. I keep it at low which maintains about 54 degrees continually. When I work in there or workout in there I move it up to 60 for the time I'm in there and then turn it back down.

It is awesome to be able to keep a stable temperature in there during the winter months and so far so good. My only question is that the floor is pretty cool and I'd like to invest in some type of floor insulation. I don't want it to raise up the floor too much but I would like it to be warmer on my feet.

Any help/suggestions would be appreciated!

Thanks!

[Joe Caff]

Put down PT 2x4's on the flat, lay in 1 1/2 rigid foam (home centers/building supply) between them, vapor barrier on top then 3/4" t&g OSB. Only adds 2 1/4 inches of height, but much warmer, drier and friendlier to dropped tools.

[Frank Pratt]

I agree. 1 1/2" of foam doesn't sound like much, but it'l make a world of difference. The extruded foam has higher R value than the white expanded foam.

[Jim Becker]

Yea, sleepers with foam board insulation between them...probably good to put a vapor barrier down first. T&G Plywood on top. You only lose about 2" of headroom and gain a whole lot of comfort. Were I knowing what I know now, I would have done this to my shop a long time ago, but that train has left the station. There was an article in FW quite awhile ago that showed this method during a shop construction.

[Charlie Velasquez]

Yes, but you may also consider eliminating the sleepers. You can get insulation with compressive strength from like 25psi to like 100psi. More than sufficient to support even the heaviest of machine tool.
Laying 2x4 sleepers on the perimeters and 16” centers means about 25% of your floor will have an r of about 2, while the rest has an r of 7.5.

edit: you didn’t mention your current floor. If it is concrete, then you need pt sleepers, so the r of those would be lower than kiln dried construction 2x’s.

[Jan Smith]

Yes, but you may also consider eliminating the sleepers. You can get insulation with compressive strength from like 25psi to like 100psi. More than sufficient to support even the heaviest of machine tool.
Laying 2x4 sleepers on the perimeters and 16” centers means about 25% of your floor will have an r of about 2, while the rest has an r of 7.5.

edit: you didn’t mention your current floor. If it is concrete, then you need pt sleepers, so the r of those would be lower than kiln dried construction 2x’s.

How would you go about securing the plywood floor?

[Jim Becker]

How would you go about securing the plywood floor?

It would have to be a floating floor with the T&G plywood or Advantec panels glued together so they become one big sheet...which is certainly a valid option.

[Lisa Starr]

If you lay ISO board, you can skip the sleepers. ISO gives you an R8.5 in 1.5". You can then lay 3/4" T&G over it and just screw thru the insulation into the old floor. It is basically how many, many commercial roofs are made. ISO is available at any local commercial roofing supply facility.

[Bob Coates]

I have put 3/4 " rubber cow mats on my concrete floor and found that helped. I did not put it under tools that were on stands is so it is only on the walk areas.

[Jim Andrew]

I used 1" pressure treated deck flooring for sleepers, put 1" blue dow foam between, then put T&G flooring over that. Only used 1 3/4" of ceiling height, and the shop stays about 10 degrees warmer. Better to walk on as well.

[Terry Therneau]

I laid Fomular250 sheets down with OSB over the top, and staggered the seams. No glue or nails. It has been just fine, going on to the 3rd winter. I can roll machinery around, though I don't need to do it much given my layout. If you conservatively assume that the sheathing can distribute the load of a caster over a 10" square, that's 1 ton (25 psi). The only place I wimped out was directly under my bandsaw, a 26" Moak that weighs 1100 lbs, but I suspect that it would have been fine as well. The shop is 22 x 28.

[Doug Garson]

Surprised no one has asked this yet. What is the existing floor? Can you get under it to add insulation, can you rip it out and start over?