I'm using a product by Zurn called therma board that similar to a warm board... I glue and screw 5/8" MFD panels with Aluminum flashing/top over my 3/4" sub floor.  How have people tiles over such a product?  Zurn and I think warmboard recommend screwing a backer board down a anti friction membrane, thin-set, tile

The problem is that a backer board according to the manufacturers the board should be thin set to flooring below, which cannot be done with the zurn panel because of the aluminum and type of material.

Was wondering how others have done it?

I far as I can see my options are

-gypcrete no panels (expensive, weight is there the same efficiency?)

-tubes under subfloor (my tile area at this time is quite large so I'm not really a fan of this)

-buy / make 5/8" plywood panels for tubing...(a product made of plywood with no aluminum solves the problem. Not sure about the efficiency compared to board with al.) Where can I buy? who makes a panel?

-go with wood floors instead of tile...but need a suggestion about how to level floor.  Could I use the roof shingle method under zurn panel or would there be an odor during the heating season.

 
Thanks

 

First off, that product is not similar to warmboard. it has very little aluminum and very little tubing contact to the aluminum. Performance is very different. It might be a fine choice for you but I would never compare those two products.

My understanding is that thinset becomes inert once it sets. that said, MDF can't handle moisture. Warmboard or real plywood panels can.

What you need is at least partly defined by your heat load.

Densguard from Georgia-Pacific is fastened with nails or screws and needs no thin set under it. You could put it directly on top of the Warmboard or Thermaboard. It's available in 1/4" thickness. You assure the required flat surface for tile by making sure the subfloor is smooth and level. Densguard is available at Lowe's. It's also available as DensShield from contractor supply houses. I used it behind the 1400 sq ft of tile I put on the floors and walls in my house, except the showers where I used Kerdi over regular sheet rock. It's also waterproof, or at least water resistant.

Sorry I was so late to the party - been away from the forum for a while.

Go to this link: http://www.thermalboard.info/pdfs/ThermalBoard_inst-app_manual.pdf. The recommendations for tile are on page 23. You CAN put backer board over Thermalboard. You can also use thinset as described in the manual. My personal experience is that you can also thinset below the backer, as many tile folks recommend, in order to fill any irregularities and level the backer board. Thinset won't hurt the aluminum or the PEX, and as NRT.Rob noted, it is inert once set. While its performance does not match Warmboard's, only your heat loss calcs can tell you whether it will be sufficient for your application. Water temps may need to be raised or lowered. Get a heat loss, use the recommended temperatures from the manual, then fiine-tune as needed to prevent over-cycling or under-performing.

NOTE: Although this is not an authorized response from Thermalboard or Zurn, I believe you can dispense with the anti-fracture membrane when using thinset, provided you have a solid subfloor assembly below with no deflection. The backer board and thinset will protect against the delta of expansion between the tile and the subfloor/thermalboard.

As for the MDF concerns about moisture, yes, you must protect it from moisture during the process. If you set the tile and edging properly, moisture shouldn't be a concern going into the future. For plumbing leaks, it won't be as forgiving as plywood if it ever does get wet later, but it shouldn't get wet if everything is done properly.