Has anyone had any experience with this – we have a customer who has radiant heat over which we will install ash flooring. Because of chemical sensitivities, they want a foil faced paper used under the wood flooring instead of regular rosin paper, to seal potential outgassing from the underlayment. We haven’t found any specific recommendations against this, but at this point are agreeing to do it only without a warranty. Any ideas? Any related experiences would be helpful.
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Question for Clarity:
The floor will be (from top layer to bottom)
1) Some sort of finish like water based poly
2) 3/4" Ash (tongue nailed)
3) Foil faced something or other
4) OSB or Plywood underlayment
5) RFH
If this is the case, I am afraid that the foil faced barrier will be an effective thermal barrier. Just a guess though. . . .
Why not seal the subfloor with some type of non-gassing paint on sealer and skip the foil which will be a thermal barrier but on the other hand if you insulate and use foil under which I have, the heat will still get through.I have two layers of 5/8 ply, hardwood on top and it works great.I'm guessing that with the foil side up you will have less of a barrier than I do.
How would the foil become a thermal barrier? I see it as one large heat pan ,spreading the heat more evenly through the floor.
That is a good point. I am sure that someone will chime in with the comparison between convection and conduction. Your point leans towards conduction since all the materials are in contact with each other.
I am interested to see where this goes.
My opinion is that the poly on the finished floor will be an effective barrier. . .(if that coating itself is not "outgassing" too much for the owners, that is. . .)Steelkilt Lives!
Foil is a thermal barrier when it can reflect radiated heat. That requires an air (or vacuum) gap between the foil and the radiating surface. If the foil is touching the warm surface, the subfloor in this case, the heat just moves into the foil by conduction.
To clarify,
The floor will be (from top layer to bottom)
1) Water based poly
2) 3/4" Ash (tongue nailed)
3) Foil faced paper - the product is called Aluma foil, and is a sandwich of foil, paper, foil, sold as a vapor barrier to seal out gasses from building products for chemically sensitive people
4) Plywood underlayment
5) RFH
There will also be some type of insulation under the RFH, though the owners haven't determined yet what will be acceptable.
Our concern is how this will affect the perfomance of the ash flooring, as well as the effectiveness of the heat. On the one hand the owners are asking us to lay the flooring over a vapor barrier, but on the other we will be poking that barrier full of holes when we staple the floor. (We recognize that a vapor barrier poked full of holes won't work, but they think it will be "better than nothing.")
To respond to another post, the first option discussed was to seal the plywood with a water based sealer, but the owners were concerned that all the sides and voids would not be sealed so it wouldn't work.
Thanks for the input!
Edited 3/3/2003 7:24:01 AM ET by RenBuild
Edited 3/3/2003 7:26:28 AM ET by RenBuild
Why not just pour a 2" concrete overlay which would seal everything ,plus give you some thermal mass, then cut it and stain it to look like wood .2" of concrete adds about 15 #sq.ft. and most codes call for around 45 so you should be okay.
That sounds like it would solve the problem, but they have their hearts set on wood, so I don't think they'll go for it. Thanks for the suggestion, though.
We are mostly concerned with how the wood floor itself will perform (we tend to agree that the foil faced paper will improve the performance of the heating system.) Even the manufacturer is unwilling to make any commitment in this area - probably because it hasn't come up for them before. It's tough to offer a warranty for our work in this case, because no one seems to know what might happen a couple of years down the line with this foil product under the floor.
Performance of the wood flooring will depend on how well humidity is monitored,I don't worry much about it so I get lots of shrinkage in winter then in summer everything tightens up again.