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Warmest insulation between a Concrete subfloor and a floating floor?


neewest's Avatar
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09-18-13, 04:23 PM   #1  
Warmest insulation between a Concrete subfloor and a floating floor?

I live above a loading dock, where there is lots of cold air especially in winter. I have the heat on 90 and my house only gets to 60. I have a chance to remodel my floor and want it to be as warm as possible. Radiant heat in the floor would be the warmest, however I don't have $15,000 to do that. Here are the options I have found.

1. 1" foam board under the floating floor

2. Radiant Barrier (reflective foil). There is the plain foil, foil between bubbles and bubbles between foil.
The companies keep negating what the others are saying, so I am really confused if it will work at all. Here is all I have been told: 3/4" of airspace is required to make it reflect heat, otherwise it just conducts it. Foil will disenegrate because of the lime in the concrete.

Has anyone used it between concrete and a floating floor?

What is the warmest insulation layer I can use between concrete and a floating floor?

 
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09-19-13, 10:36 AM   #2  
I don't see 1" of foam making a huge difference but that (or more) and air sealing would likely help.

I don't see the radiant barrier doing anything for you.

 
Gary in WA's Avatar
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09-19-13, 10:42 AM   #3  
I agree, forget RB here. Fig.7; BSI-009: New Light In Crawlspaces — Building Science Information Cover with 5/8" Type X drywall, fire-tape.

Gary

 
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09-20-13, 09:11 AM   #4  
Gary?

What does Cover with 5/8" Type X drywall, fire-tape mean? Put 5/8" drywall down on the floor and seal the seams with fire tape? and then put my floating floor on top of that?
I cannot change anything outside of my airspace in the unit, due to HOA rules.

 
Gary in WA's Avatar
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09-23-13, 10:24 AM   #5  
Sorry, I was confused... Install XPS on the concrete slab, then plywood or wood sleepers + plywood on the foam board. Fig.2; BSI-003: Concrete Floor Problems — Building Science Information

The thickness of foamboard required is set by location; 2009 IECC Climate Zone Map - Colorado

It needs to be thick enough to prevent condensation in the cavity; IRC FAQ: Insulating Sheathing Vapor Retarder Requirements — Building Science Information

The outside air will be tempered somewhat as the building below may be heated (?) otherwise use the link given.

Gary

 
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09-24-13, 09:43 AM   #6  
Gary?

I am doing a remodel, so if I follow your advice I would have to cut all my doors and door trim down, which may include a steel fire door into my hallway. I essentially live in the Ritz Carlton building (they are my HOA that does nothing to help us employee housing people).

If I cannot cut the doors down, and I don't have more than an inch or so to work with, what can I do? Can I do XPS 1/2" foam then the floating floor to at least get an R4 instead of an R1 with cork?
There are tons of XPS foam, some are blue, some have reflective foil on the outside...which one is the best?

Thanks ;-)

 
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09-26-13, 08:40 PM   #7  
Usually there is 1+" above standard door installs, require removing/resetting/retrimming- added wax ring/extension at toilets. If you are limited on the foamboard thickness, use PIC; foil-faced polisocyanurate board at R-7 per inch. Use canned foam to make it air-tight at the concrete.. You don't mention the temperature of the area below so it would be hard to give an answer on f.b. value for such minimal thicknesses. Eg. read page 15, 16; http://www.buildingscience.com/docum...ting-sheathing

Using R-3.6 per inch of insulation thickness, with 1" PIC (R-6.5 + R-1; ply/flooring) yields (2") or 89% of heat flow stopped, second chart; http://www.google.com/url?sa=t&rct=j...,d.cGE&cad=rja
Use the 1" R-value for 1/2"PIC.

Any foamboard you add will cut the heat flow, preferably thicker. OTOH, the loading dock may be heated from personnel/forklifts, etc. so the temps may be lower and your heat loss even less.Though this may be minimal.

Gary

 
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