Wooden floor thickness for shop

[Richard Gonzalez]

I am another who had concrete floor. Put down 2x4 sleepers flat, some 1.5 foam insulation and regular 3/4 flakeboard subfloor. So much more comfortable during winter (in Colorado above 6000 feet). Personally, I like a little bit of springiness in floor. Have a job where I’m often on my feet for 8 hours on concrete and my feet and legs kill me. Can spend 12 hours in my shop with no pain. It’s a shop - never did anything to finish floor, just the bare flake board.

[Dean Coss]

Don't forget insulation, cold feet are a misery.

How does installation of insulation under a floor work and what kind? I was thinking some of the pink foam sheeting insulation for good moisture resistance, but how is it attached? I’m guessing that it is cut to size and glued or stapled in sections from below between joists?

[Peter Christensen]

You could go to 12" spacing of the joists with the 3/4" plywood for a stiffer floor.

[Jason Breton]

How does installation of insulation under a floor work and what kind? I was thinking some of the pink foam sheeting insulation for good moisture resistance, but how is it attached? I’m guessing that it is cut to size and glued or stapled in sections from below between joists?

I'm planning to build this style of floor for my new shop in the spring, and was thinking of doing this for insulation. I'm thinking of putting a small ledger strip along the joist for the hard foam insulation to sit on. Looking forward to seeing all the threads along these lines between now and when the snow melts.

[roger wiegand]

I put r15 of rigid foam (3") under the concrete, doubled up (6") to a 3 ft depth around the perimeter. We leveled the gravel, put overlapping insulation boards down and taped them, then concrete on top of that. (As mentioned before, the floor is then 2x4 sleepers on the flat, 3/4" plywood subfloor, and site finished hardwood flooring.) I was fortunate to find inexpensive used foam for under the floor.

[Chris Parks]

Waterproof pine board flooring 3/4" thick on a steel frame (no timber) 35 feet x 30 feet clear span under the floor. I have dropped (accidentally) a 600 lbs jointer onto that floor from a temporary hoist we made and all it did was dent it. It has been down for over 30 years now with no issues.

[Jim Finn]

I put 3/4" T&G ply as a shop floor but put the supports 12" on center.

[Thomas Wilson]

30’ x40’ is really a nice big shop. You might want to plan for heavier machines and heavier floor loads in the future. I store a bit of lumber in my shop space. I may have 300 bd ft. The wood rack is easily the heaviest thing in the shop. Also, you might want a thicker flooring layer if you want to bolt something to the floor. Top-heavy tools like a drill press are best bolted down for safety. I have had my bench bolted down. It really helps. Two sheets of 3/4 ply would hold a lag screw.

Good luck on the project.

TW

[Nick Reid]

I've got LP ProStruct with SmartFinish as my flooring material over 8" OC PT 2x4s on PT 4x4s (3' between skids) in my main shop and 3/4" PT over 12" OC PT 2x4s on PT 4x4s (5' between skids) as a 10x20 storage area off the back and much prefer the ProStruct flooring material as it has a nice finish already. The ProStruct was fine holding my 1000lb+ tractor and 600lb snowmobile, the 3/4" PT section however needs another layer of at least 1/2" plywood due to minor deflection when the vehicles sit on it. In hindsight, I wish I went 8" OC with the floor joists all around.