We are putting radiant heat under the subfloor (3/4″ Advantek)of our new house. Many rooms will have a 3/4″ oak on top of the subfloor. We were told by one supplier that quartersawn oak is the best material to use for heated floors. I am aware of the difference in expansion for quartersawn vs flatsawn lumber, but wouldn’t the dryness in the winter and subsequent shrinkage compensate for any expansion that occurs when the floor is heated? Radiant water will only be 90 degrees- like a warm day in July. Most floors would be either 3″ or 5″ wide planks.
Any comments?
Thanks
RMB
Replies
Quartersawn wood will shrink and swell less across its width than the corresponding flatsawn cut. However, it will expand and shrink more in thickness relative to the flatsawn board - it's a matter of perspective, really. Quartersawn lumber is just flatsawn lying on its side... Riftsawn is pretty much in between the two. Heat alone has hardly any affect on wood dimensions - it's all about moisture content.
I don't have experience on the radiant floor side, but I do want to point out that you'll get better feedback if you fill out your profile so people can see what part of the country you're from. Seasonal humidity swings may be the deciding point - not so big in my part of the country (Pac NW), but huge in other parts (NE).
-t
The humidity levels being consistant would do more to help stabilize a wood floor, qtrsawn or not.
Qtrsawn would be tougher per capita, so maybe that means better heat distributor or retainer. Or the real key maybe-more stable to begin with.
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I did 2 1/4" quarter sawn oak in mine, had minimal shrinkage kept a humidifier running the next season & had no shrinkage. Wide planks might be a different story
Radiant flooring heated by tubes installed under the subflooring usually has supply temperatures much hotter than 90 degrees.
General design criteria for hardwood flooring is to design (and control) the system such that the surface of the hardwood is no more than 85 degrees. This will limit the temperature related expansion and contraction to a reasonable range the wood can tolerate, quatersawn or not.
I've got radiant floors with plainsawn oak. Big mistake. Tight in the summer, wide gaps in the winter. Spend the money for the quartersawn wood. It looks better than plainsawn, anyway, particularly if you get white oak.
Andy
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You have gotten good words so far. I would add that you may want to stay away from wider boards and stick with the 2 1/4 strips.
Had a client do it agaianst the advice of the floor installer. He made them sign off on it as well.
Looks like doody now. They should have listened to the professional.
We do a lot of this type of work. I would not use wide boards with heat under the floor. Best to stick with the 2 1/4" strips. Better yet to use plywood based flooring if you aren't a purist, although nothing looks as good as the real thing.
Quartersawn is what you want to use.
You will definitely need water hotter than 90* if you plan on heating through 1 1/2" of wood on the floor.
Installing in the winter seems to work the best for us. Make sure the wood is well acclimated to the house before installation.