I'm preparing to build a sandwich above subfloor installation. My climate is mild, like oregon. Snow doesn't stick here. Humid summers. Today I opened the hardwood floor sample book from my supplier and there was a piece of wood with aluminum wrapped around the tounge and groove. I paused and ripped the wood off the presentation book and the aluminum wrapped all the way under. It is glued tight to the bottom. You can see in the photos some of the paper from the book stuck to the aluminum, so the aluminum is glued quite tightly. I emailed the floor makers and they said it is .1 mm. Which is .0039 inches. Compared to .019 inches for light weight gauge aluminum plates. Since aluminum plates major function in my installation would be to prevent stripping, would this not be an excellent way to cut out the cost and labor of the light weight gauge aluminum plates? One is oak engineered wood and the other is solid Cumaru. I'm leaning towards Cumaru with or without aluminum. My wife thinks its too dark though, but I like the stability rating of exotic woods. Also considering a unique exotic wood from Africa called Kosso wood. They can put the aluminum on any floor choice. Thank you and regards.

That's a negligable aluminum thickness. it might help with striping a bit, but it's not going to do a thing for your heat transfer. that's thinner than aluminum foil at 0.2mm. I can't imagine it's particularly good for the expansion/contraction needs of the wood either...?

Even if it were thicker, the contact to the tubing would be nearly or completely non-existant so again it's only function would be to reduce heat striping. The aluminum would not be free here, and so the question is how much is the savings, and is it worth it to lose performance? maybe, if your heat load is low enough and the savings significant. but it's definitely not a "slam dunk" at first blush.

Seriously, 4mils of aluminum ain't gonna do squat, since the lateral cross section of the stuff is just too thin to transfer much heat. Even though aluminum has fairly good refractory properties, they's have to be better than any known substance to even have an influence on striping.

It's plenty thick enough to be a good radiant barrier though, and would REDUCE, not increase the heat transfer into the floor in a suspended-tube or minimal-contact staple-up.

It's also thick enough to be a good vapor barrier, which means moisture would only enter/leave the wood from the finished surface side. Depending on how hygroscopic the species is that could present some issues too.

Plate it with the real goods, and skip the bonded foil.

Thank you for your replies. I see it's not the cure-all I was hoping.

How about with lightweight plates, would you use this as a moisture barrier anyway if it's basically free (buying directly from the maker so price is negligible for them I guess). Would a moisture barrier help a hardwood floor with expansion/contraction issues in a humid enviornment? I was planning a really stable wood like Cumaru over my wife's preference because I'm worried red oak will warp/gap over time in my humid area.

a moisture barrier would only help if it is only humid on one side of the wood. and I don't think I would want one in the middle of my floor assembly, as if you did have any moisture issues in there, it could only dry to one side (down).