Insulate floor?

[bluedog225]

Good morning,

I’m building a little room (5’x10’) in the corner of my off-grid garage to house my solar electronics (inverter, charge controller, batteries, etc). The goal is to keep the electronics, and the LiFePO4 batteries in particular, at a human comfortable temperature. This helps increase the useful life. We get temps up to 115 eff here in the teeth of the summer. Would also be great to protect them from freezing as that will kill them if they are charged while very cold.

I’ve got some mylar radiant barrier and 2.75” polyiso 4’x8’ sheets for the walls and roof.

The floor is concrete. I can put down foam and cover it with flooring. Or do nothing.

What do you guys think? Is it worth it to insulate the floor?

If it matters, winter temps here are pretty mild with occasional exceptions of 10 eff for a day or two. No such thing as a frost line as the ground never freezes.

Thanks

 

[RPH]

Make the cabinet and yes insulate the floor. The floor is your biggest heat sink. Use an incandescent lightbulb for heat if required.
Also, look at a refrigerator, doesn’t need to work. You get the whole operation in fell swoop.

 

[mike93lx]

I think I would insulate the floor. Probably make a little subfloor structure with 2x4 and high quality subfloor, then set the insulation in that. Depending on how you are setting it up, this may be something you could do later though, if needed

 

[jlv03]

I think I'd throw more resources at the walls and ceiling first, before the floor. The floor will probably follow the ground temp, which is a battle when you are trying to heat a space but isn't so bad when it is hot out and the floor is still cool. Since you need more cooling than heating, I'd work on keeping the heat out.

You'll probably need an air conditioner of some sort.

 

[bluedog225]

Yes. Will absolutely have a small air con. And probably a little heater.

I like the idea of putting all the stuff into a fridge that is located in the room. Or maybe a chest freezer.

 

[bluedog225]

How do I insulate a concrete floor? Can I put foam on it and cover with flooring, or will it crush? Or do I need to form it up and put insulation in between the floor joists? Then cover with ply and flooring?

 

[RPH]

Lots of ways to do it. Quick google search will give you ideas. Insulate everything, insure ventilation in the winter and the summer. Have a small fan to circulate the air inside the closet. Electronics run hot.

 

[acer66]

One way and I never seen it done with Rockwool before.

Subslab Insulation With Mineral Wool - Fine Homebuilding

Learn how and why Rockwool Comfortboard was used to insulate a subslab under what will be a finished concrete floor.

www.finehomebuilding.com

 

[mike93lx]

One way and I never seen it done with Rockwool before.

Subslab Insulation With Mineral Wool - Fine Homebuilding

Learn how and why Rockwool Comfortboard was used to insulate a subslab under what will be a finished concrete floor.

www.finehomebuilding.com

Comfort board is different than the stuff you out inside walls. It's rigid and can handle exposure to the elements

 

[WisJim]

I would consider insulation around the perimeter of the floor on the exterior instead of and/or in addition to insulating the floor surface.

 

[PoorUB]

If you are trying to keep it cool insulating the floor is probably not necessary. Have you ever checked the floor temp in the summer? That would answer your question.
If you insist on insulating it, as long as the floor is flat, I would lay down 2x2 green treated for furring strips on 16" centers and put 1-1/2 foam in between, then build over that.

 

[Fav Onefour]

I'd agree with @PoorUB about insulating the floor. In a warm climate the floor will be the coolest surface in the room most of the day.
Years ago, I poured a new slab in my garage workshop. I put insulation under the slab, but didn't add insulation in the walls or ceiling. The ceiling needs more, but I have decking to fight. Anyhow, the workspace is hotter in summer than it was before the insulated slab.

Another side note to my project. I also poured the drive over insulation at the same time. That ****** will hold snow quicker than the uninsulated slabs around me. The other slabs are still holding on to the warmer ground temps early in the season.

 

[bluedog225]

Interesting points. It’s a voided slab so it tracks ambient better. Was about 90 eff in the interior when 100+ outside. Though climate controlling a 5’x10’x9’ space seems pretty easy. Not fighting the slab, hot or cold, seems wise.

 

[Mzungu]

I would insulate it. The room is small and the cost will be minimal.
- Lay down some 6-10mm poly if the slab was poured without one
- Install your 2 x 2 sleepers on 16" centers as already suggested.
- insulate with 1.5 to 2 inch blue or pink xps between the sleepers, depending on the actual dimensions of your sleepers.
- cover with 5/8 plywood
- floor covering of choice, or just paint the plywood.

 

[Mzungu]

One way and I never seen it done with Rockwool before.

Subslab Insulation With Mineral Wool - Fine Homebuilding

Learn how and why Rockwool Comfortboard was used to insulate a subslab under what will be a finished concrete floor.

www.finehomebuilding.com

Works great, but it is normally for below the slab.