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Discussion Starter · #1 ·
Hey all, first post here and looking for some direction/correction/affirmation of my understanding of a tile job I'm starting.

Here's the specifics:
floor trusses spanning 24' (16" or 19" o.c. haven't decided yet) with a deflection rating of 480.

1/2 pex radiant tubing will be stapled up to the subfloor.

porcelain tile will be throughout the entire house, including bathrooms and kitchen.

my questions: is 3/4 OSB t&g with underlayment sufficient or should i go with 1 1/8" OSB? Or should I stick with 3/4" and add a layer of 1/2" plywood and then underlayment?

also, any recommendations for underlayment? looking at durock, permabase, or green e-board.

I would appreciate some ideas. have the TCNA manual and trying to get as much info as I can from this also.
 

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Discussion Starter · #2 ·
One of my concerns is whether I should use a membrane to "uncouple" the tile from the subfloor, due to the heat from the radiant. If so, any recommendations for a high-quality membrane?
 

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I'm The BOSS
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I'll be the first to ask your back ground.

usually a post in the introductions is common here.

your using clear span floor trusses, not I-joist ? correct ?

what is the under side of the joist going to be finished with ?

is this a customer or your personal property.
 

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Discussion Starter · #5 ·
I'll be the first to ask your back ground.

usually a post in the introductions is common here.

your using clear span floor trusses, not I-joist ? correct ?

what is the under side of the joist going to be finished with ?

is this a customer or your personal property.
Sorry for the lack of introduction. I'll head over and do that. I'm currently building my own home with the help of my retired father. I'm also building his home and two homes for my sisters. I'm not getting into anymore detail than that because it's not needed. I live in North Dakota where it's virtually impossible to find contractors right now and so I've taken a few year sabattical to build. I'm sure you're all thinking the work I'm doing should all be on the Wall of Shame thread, but it's not. My dad was in the building trades all of his life and since I'm living in it, I'm building to the best of my ability and knowledge. Hence why I'm here gathering info and hoping to offer my experiences to others.

Anyway, using clear span floor trusses. Underside of trusses (basement ceiling) will eventually be finished with drop ceiling.
 

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I'm The BOSS
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ok,
If it's yours go over board and do it right x 2

I would use 3/4 glue and screwed or nailed
then perpendicular to those sheets us 3/8" or 1/2"
then wonder board, glued and screwed
also strap basement 24" o.c.

that will hold it tight for sure
 

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I will second the warm board. It is thicker and more money, but provides a superior heat transfer. Osb is a fairly good insulator. You will be much happier with the warm board.
 

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Paul
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ok,
If it's yours go over board and do it right x 2
I'm not sure I understand that logic. That's what I do on customers jobs. If I'm going to take chances or try something new it's on my own ****.
 

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jaydee said:
ok,
If it's yours go over board and do it right x 2

I would use 3/4 glue and screwed or nailed
then perpendicular to those sheets us 3/8" or 1/2"
then wonder board, glued and screwed
also strap basement 24" o.c.

that will hold it tight for sure
If he's stapling pex "up to the subfloor", meaning running the truss bays and looping them at the band joists or beams. Alll that flooring will act as an insulator, and make the radiant less effective.

To the OP:

Have a pro do the calculations for you and map out the rooms. You can do the install based upon the pros map for the rooms. Money well spent.

In terms of an uncoupling membrane, I would use one.
CBP makes a green membrane: spiderweb.

We don't use them often, but when we do, this is what we use.

This application I would use a membrane.



Thermal track, to run the pex from above.
 

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Discussion Starter · #10 ·
Thanks for the info. Tenon, I am working with Radiantec, out of Vermont. They are very knowledgeable and we have worked closely on the slab installations (garage and house basement so far). I'm planning to use plenty of their aluminum heat transfer plates, which also make the stapling to the subfloor very easy.

Those Thermal Track and Warm Board products seem very intriguing. Anyone know an approximate price/sq ft? The only drawback I see is in the event of a pipe failure, it's inaccessible, unlike the staple-up method in which it can be repaired. Not anticipating failure and haven't had a failure in the past with previous radiant installs, but it's nice to have access.

Thank you all for the suggestions.
 

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TheDude1946 said:
Thanks for the info. Tenon, I am working with Radiantec, out of Vermont. They are very knowledgeable and we have worked closely on the slab installations (garage and house basement so far). I'm planning to use plenty of their aluminum heat transfer plates, which also make the stapling to the subfloor very easy.

Those Thermal Track and Warm Board products seem very intriguing. Anyone know an approximate price/sq ft? The only drawback I see is in the event of a pipe failure, it's inaccessible, unlike the staple-up method in which it can be repaired. Not anticipating failure and haven't had a failure in the past with previous radiant installs, but it's nice to have access.

Thank you all for the suggestions.
I'm familiar with the aluminum transfer plates.

I understand your apprehension on it being inaccessible, but I will say this:

Un-molested pipe under CBU and/or flooring "should" never need to be accessed again. The feed and return are accessible through the "manifold room".

Pressurize the entire system throughout the flooring install.

Others have suggested a visqueen mapping of the loops as you install the underlayment or flooring.

Check the pressure throughout the flooring install, although, if you hit the pex, you will hear it, repair, re-pressurize, and finish the install.

With the cost of aluminum, the thermal track may be cheaper.

I think your fear of the "field" of the pex being accessible, is probably unwarranted.

This newer formula of pex is not the same composition as it was 25 years ago, when the hot lines were blowing at the brass joints.
 

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The Remodeler
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I paid roughly $3/sqft for my Sunboard panels, but that was their econo-line... Warmboard is easily double.

I have extruded aluminum track under my second floor. Since it's an old house with T&G finished floor laid directly on joists, I glued and stapled 1/2" OSB to the underside of the floor to actually slow down the heat transfer. That extra layer of OSB actually helps even out the temps to the finished floor. Yes, you could say it's an insulator, but the heat will still quickly push through. 1/2" OSB has an R-value of only 0.51. Plywood is roughly the same.

As far as the tile installation goes, I'd do 1/2" ply over the existing 3/4 OSB and then Ditra.

What are you using for a boiler? Im assuming Radiantec discussed Mod-Cons with you.
 

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Put the tubes onto 3/4" osb and pour gypcrete or other light weight concrete ontop.
 

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Hair Splitter
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ok,
If it's yours go over board and do it right x 2

I would use 3/4 glue and screwed or nailed
then perpendicular to those sheets us 3/8" or 1/2"
then wonder board, glued and screwed
also strap basement 24" o.c.

that will hold it tight for sure
Always run the ply (or any material) with the joists not perpendicular to them. Just stagger the joints, glue and screw.
 

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