Tiling with natural stone over radiant
I have a new bathroom where we would like to install hydronic radiant then tile with 1/2″ natural slate stones.
This is a circular bathroom having an inside diameter of just under 9 feet. The framing is 2X10s on 16″ centers, and I already installed 3/4″ plywood subfloor (screwed and glued) over it. The deflection calculated from the John Bridge site is L/960, and this would be worse-case scenario since the room is circular and the joist span decreases from the center.
There is an additional 1.25″ height to work with, to meet with the level of adjacent finished floor.
The joist spaces are still open and accessible from underneath for installing utilities.
I am wondering what the best strategy would be for installing hydronic tubing AND providing an adequate base for the slate stones in this scenario.
Any thoughts appreciated!
Replies
I don't think you have quite enough height - deducting 1/2" for the tile and some for the setting bed leaves you with maybe 1/2" for PEX tube or rubber hose ... not enough. Plus 3/4" subfloor isn't enough either - you need 1 1/4" minimum (before cement board) - unless you use Ditra.
First I would read this: http://www.schluter.com/3765.aspx
Maybe consider putting the hydronic under the subfloor or going with an electric mat instead, possibly. Or, possibly accept the fact that the tile will be above not flush with the adjacent floor - that would give you more working room.
Jeff
Edited 7/13/2009 9:00 pm ET by Jeff_Clarke
I'm okay with the tile being a bit higher than adjacent floor, I can transition at a door threshold.
My original thought was to router a path for the PEX into the cement board (as seen on previous FH discussions), then tile over that. But now that I am considering the thicker slate tile, should I skip the cement board and add another layer of subfloor with PEX routered into that?Shawn
I would go Uponor quick track then ¼" hardi , then tile. Will end up just a speck over your adjacent hieght.
Don't rout grooves into the cement board. You won't get very far. And you don;t want the rough edge of the cement board rubbing against the PEX.If you need actual room heat, then you need radiant hydronic. Most of the electrical stuff is "comfort" only in terms of just outputting enough BTUs to take the chill off the stone. On top of your subfloor you can add underlayment with grooves routed into it, or ply strips spaced 8" oc with a gap between the strips to hold the PEX.Then Ditra over that. I'd recommend the -XL. Then the slate over the Ditra. Watch out for crapy home depot slate. Much of what you get is more like shale, very dirty, very flakey, very soft.
The Schluter Ditra membrane looks like just what I need. It would save the added thickness of cement board, and uncouple the stone tile from subfloor. After reviewing their installation handbook, I have a couple Q's for my application.
I would like to install the radiant tubing over the existing subfloor by using 3/4" plywood sleepers and pex in Thermofin U heat transfer plates. Can I put the Ditra membrane directly over this assembly, just filling the small airspace above the pex runs with the latex portland cement mortar?
Secondly, the room i am working in has a curved wall (basically the room is a 9ft diameter cylinder)...how do I handle the floor/wall interface (would the recommended Kerdi-Band conform to a curved wall)?
Thanks for the help!Shawn
Since it is a 'system' you should contact the manufacturer to get their input - or find a company rep.
Jeff
I was gonna say..........do the snap in in the 3/4 ply then Ditra over. Did one last year with 21" Crema and it came out nice.............and warm!
"When the spirits are low, when the day appears dark, when work becomes monotonous, when hope hardly seems worth having, just mount a bicycle and go out for a spin down the road, without thought on anything but the ride you are taking." — Sherlock Holmes, 1896
I was gonna say..........do the snap in in the 3/4 ply then Ditra over. Did one last year with 21" Crema and it came out nice.............and warm!
Were you using heat transfer plates? Please explain how you did this.
Thanks!Shawn
The plumber that did this job is a radiant whiz so far as I know. He has extensive experience and I believe his background is engineering for what ever that's worth.
This job he did not use plates as he uses a routed out plywood system from a guy in the northeast that makes them in a shop. They are much less expensive than the name brand stuff like Uphoner and Viega. The tubing is name brand not sure which and snaps in to the tracks with a rubber mallet.
I filled in the gaps with thinset one day then Ditra the next. Did the stone install a few days later. We ran the tubing thoughout the room so the shower floor and the soaking tub were nice and warm.
Eric
"When the spirits are low, when the day appears dark, when work becomes monotonous, when hope hardly seems worth having, just mount a bicycle and go out for a spin down the road, without thought on anything but the ride you are taking." — Sherlock Holmes, 1896