Dry system question

Henry_9

Gentlemen:
I spent part of the day with a flooring contractor discussing the pros and cons (ok, pros only) of rfh and hard wood. He is in the midst of a rehab where the first floor has plywood down and the second is joist only.

I have experience with the Roth styrofoam / aluminum, I designed a retrofit into a basement. I have not used the Quik Trak system by Wirsbo / Stadler to any extent or the Warmboard type system, but the floor guy needs something structural for the second floor and needs to nail through the radiant layer on the first floor to get the finished planks into the stable plywood subfloor.

To make matters more interesting, since the planks are so large, 10" wide and 14' long, they must be glued and nailed. I am not real excited about total isolation of the planks as temperature change can obviously wreak havoc on a plank that size.

Finally, he has a preference for only 2" nails, probably because that is size feeder he has for his gun. Is the Roth board structurally strong enough to hold a nail that is only 1/4 of an inch into the plywood subfloor beneath, he seems to think not? Is there any problem with using a 2.5" or 3" nail? Is there anything else that I could recommend that is structural like the Warmboard product for the second floor.

Ideas would be welcomed.

Thanks,
Henry
Viessmann Midwest

hr

If the upper level

is currently just joist, I would go with the Warmboard. In addition to being the ONLY actual approved subfloor, that continous aluminum layer will be very kind to that wide floor and accomplish the heating at the very lowest supply temperature.

While I have not tried every product on the market, I have installed WB and run tests on it. It does perform both as an excellent heat emitter and a kick butt subfloor product.

Not sure about glue and nails on wide boards like that. I think they are going to want to move. I wonder that the glue might keep them from doing so and cause possible cracking. I'd prepare the HO for some shrinkage movement, and related gapping. Just the nature of wood.


Really the wood flooring should be nailed with a hardwood cleat (a serated, tapered flat nail) through the tongue. This allows shrinkage and expansion movement and a hidden fastener. Nailing through the tongue also allows the floor to be resanded and refinished without hitting fasteners.

hot rod

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jerry scharf_2

them's wide planks

Like HR says, warn the owner about some gaps... I'd go with something that keeps the water temperature as low as possible. I would use either warmboard of thermofin thinfin U mounted panel up on sleepers. They each have their advantages and drawbacks (I'm using both.) Make sure if you go witht he warmboard that you don't put too much silicone in, or it can push the pex into contact with the floor and cause noise...

You need really good control of the humidity of the house. The more the wood moisture changes, the more it moves around. In an leaky house you're looking at losing too much moisture, in a super tight house you're probably looking at too much moisture...

jerry

kevin coppinger_4

the real key is....

moisture. I did a job featured here at FAP. The planks were 12" to 17" wide in old growth pine. I used the wirsbo quick trac and used a regular mixing valve to control the temp. They have had no problems to date (and these people were/are fussy.) The key for me was the flooring sat on a radiant heated floor for 45 days, spread out to get the moisture content down. looked great, performed well. kpc

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Henry_9

Thanks for the photo

Hotrod. I imagine the floor guy may already know this, but I am learning.

I saw an interesting tool, it was a cross between a hammer and a nail gun. As each successive piece of plank was laid, it was locked into place with a bump and then nailed on a 45 through the edge. Might be the ticket for these planks.

I would have thanked you earlier, but i have been at the hospital all weekend, my wife just gave birth to son number four. As much effort as I put into my work and as important as it is to me, it means very little compared to this. So, belated but appreciated thanks.

Henry

Viessmann Midwest