So yeah. That’s what I’m looking at doing.
Foam under Tile.
If you’re just going to berate me, at least start your comment with a 1 to 5 stars (*) so I know the level of berating intended…
Or you can hear me out first… Doubt it..
I’ve got floor joists with varying height. But not from joist to joist. I mean I can set the height of the floor joists wherever I want. I have that option in my unique situation.
So picture this:
Joist
3/4 dry pli
1/4 foam board
5/8 to 3/4 layer plywood w/ radiant
1/16th aluminum layer(yeah, I just have it already. I’m not crazy or loaded) (with money I mean.. **hickup**)
(no air gaps if I can manage.)
Mortar/thinset to support
Backerboard
Crack isolation layer
Mortar/thinset
Foam board (jk!)
1/4 inch 12×24 porcelain tile
5/8 gap between bottom of door seal when opened to allow for mats and rugs.
Any reason that wouldn’t work with plenty of care around the Radiant Pipes and adhesive between all possible layers? (Liquid nails or caulk depending on which is best. Actually, caulk the foam layer?! Both sides?..)
Ok, I might be crazy. You have been warned/beaten to the punch.
Thanks for your help!
1/4 inch 12×24 porcelain tile
5/8 gap between bottom of door seal when opened to allow for mats and rugs.
Any reason that wouldn’t work with plenty of care around the Radiant Pipes and adhesive between all possible layers? (Liquid nails or caulk depending on which is best. Actually, caulk the foam layer?! Both sides?..)
Ok, I might be crazy. You have been warned/beaten to the punch.
Thanks for your help!
Replies
What are you trying to do with the foam? you get R1 from a quarter inch of foam. would be better to insulate between or below those floor joists.
If not for the insulation, why include it?
It's available. Also, if it's not going to cause problems or cracking, it's not a big deal to throw in. Like I said, it's available and no additional cost. So why not do it is the question I want answered. If the best reply is "because it could be a problem", then that's little help. Without a guarantee or at least a high likelihood of failure or other problems occuring, I'll probably do it and live with consequences. If it's going to happen do please let me know. I'm not trying to screw it up after all.
Thank you!
Part of good construction is about economy of material. Adding something doesn't make it better, adds to labor (effort and cost) and creates a variable of unknowns. Having doesn't require use. Use is a choice based on reason.
I would omit the layer(s) of foam. I simply don't see a return - unless it's foil faced, maybe.
I like the aluminum with the radiant, especially if it's free. How do you intend to fasten it to the radiant ply? If you puncture the radiant tubing, the repair difficulty multiplies.
You may want to consider bonding the backerboard to the aluminum using a troweled urethane adhesive.
Frankie
So you have excess material. options include:
-returning to the source (if you purchased it) for credit
-donation to charity (possible tax deduction)
-pay to ship to landfill
-keep for possible future use
-bury in your new floor
IDK why paying to ship to landfill was even included. That's a sucker bet for sure. Charity is something I hadn't thought of but I think the quantity, I'm only doing <100 sqft at this time, would seem like a trash dump to them. Its not in the condition, but good enough to walk on. Lol
"If the best reply is "because it could be a problem", then that's little help. Without a guarantee or at least a high likelihood of failure or other problems occuring, I'll probably do it and live with consequences"
If you want a guarantee of failure you won't get it for 99% of construction material or techniques. I've seen some pretty shoddy stuff that didn't fail.
Fair enough. I was just trying to get a firm confirmation on the outcome. I guess my question might not have an answer so clear cut.
Your method has not been tested, therefore no one can really advise if what you are doing will work or not. It could be an expensive test for you. I’m not sure you will gain much if anything at all for the extra work. When building in an unorthodox manner it usually ends up backfiring (not always). Also, I think that if your method were to show a lot of promise the radiant suppliers would be selling 1/4” foam and aluminum sheeting off of their shelves. Radiant has been around for awhile, I would suggest you follow the steps that engineers and industry professionals have established. Maybe it will work out well for you, maybe not.
Is this stuff the quarter inch fan fold meant for walls? if so, it should include perforations to allow vapor to move through it, so no issue there.
the aluminum plate may complicate your fastener choices, so consider that.
You have included an isolation layer between the tile and the subfloor, which is good.
The aluminum is less than 1/16 inch. I rounded up. It shouldn't be a problem to puncture with screws. Unless you mean something I'm missing?
Depends on what kind of alloy the aluminum is.
You also have quite a few layers here, and may have a challenge to calculate exactly where to put those joists, elevation wise. (depending on how many layers of adhesive (caulk is not the thing to use) between layers.
it is good to have that aluminum layer, if you will take advantage to increase the distance between hydronic runs in the floor.
are you concerned with the aluminum trapping moisture under the tile isolation layer (DITRA or similar). Might want to perforate it.
any update?
I would not put "foam" under tile or tile-underlayment. Foam is not structurally rated meaning it should not be used to bear load. Of course, you can building anyway u want but if the tile starts to crack ur going to be ripping the whole floor out!!
Imo: Foam insulate under 3/4 dry ply (primary floor) in between the floor joists, have fun working under the structure