I am renovating a 100 year old farmhouse in northern MN and would like to add hydronic heat under the floor on the main level. The flooring consists of three layers- pine planks boards covered by pine shiplap boards covered by the top layer of hardwood flooring. There is also a layer of tarpaper between the bottom two layers. It is supported underneath by 2X6 joists on 16″ centers and I have open access to everything at this point. My hope was to install the PEX, then insulate with ccSPF. However, I have been told that the tarpaper will emit an odor if heated by hydronics. I have also been told that it would be hard to drive the heat through that much wood, so I am reluctant to go forward with the project for these reasons. Any thoughts/experiences appreciated…
shawn
Replies
I have heard that tar paper could outgas. My thoughts would be to see if you can get at a piece of the tar paper and throw it in a oven and crank up the heat. See what kind of smell you get, if that helps.
All that floor would have to be figured into the R value to calculate your heatloss.
That's were you should start, "heat loss"
The folks over at heatinghelp.com , "the wall" are the real pros and very helpful.
Both recommendations are true.
In removing some finish flooring recently, I was back-cutting cut nails to salvage the quarter-sawn oak and had a fair amount of friction heat going on the (40 YO) tarpaper that was used. It stank to high heaven and smoked as well. Back then, I think the quality of the asphalt must have been higher. Now hydronic rarely gets a floor above 90 degrees but I wouldn't want to smell that smell again.
Wood is a great insulator so the other point is true too. I would shoot for some fin-tube above the floor, which can be 'built-in' in older houses ... toe kicks of built-ins, etc.
I'd also be leery of drilling a lot of holes through 2 x 6 floor joists (on what span???)
Jeff
Edited 11/29/2007 9:58 am ET by Jeff_Clarke
suppose we could drag those 8x8 hand hewn precrowned beams over here to help support this?
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Maine humor = oxymoron ;o)Jeff
1) The tar paper is so old that it MAY not smell if you warm it (as another poster mentioned, your floor temp shouldn't get much over 90 degrees), but I wouldn't count on it.
2) That's a lot of wood to try to get heat through. If you really want to do this, you might consider removing the hardwood and the shiplap layer of underlayment. (Or if you have the room, leave the underlayment in. If you leave it in, and heat from above as follows, then I don't think I'd worry about the tarpaper other than to maybe lay down a vapor barrier over the underlayment.) Then lay something like WarmBoard or QuikTrak -- plywood with grooves for PEX tubing -- and then re-lay hardwood. Insulate the joist spaces below.
Mike Hennessy
Pittsburgh, PA
The thickness of the wood is a definite challenge.
The tarpaper might emitt smells and might not. Also some people are more sensitive and others don't even notice. I wonder if there is a way to test an area by warming it first to see if yours stinks.
Some of that really old stuff was pitch paper, not just tarpaper. It has a unique smell of its own that never fades with time, and is somewhat toxic. The asphalt smell would be barely noticeable to me, but I could not live with warm pitch smelling things up.
so be sure you know before you go
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