We have radiant floor heating (generated by an outdoor wood furnace). Water temperature is 100 degrees with pex lines installed under 5/8" plywood. We have been warned away from certain hardwoods and are trying to determine what would be the best choice that will withstand this water temperature without drying or warping.

Any suggestions would be appreciated!

If you are looking to do a solid hardwood floor, the wood should be either quarter sawn, or quarter sawn & rifted. That way, the wood expands up and down rather than side to side. This assumes that you have at least 3/4" plywood to nail into. Generally, you would need to buy this unfinished as it is rare to find prefinished wood w/ these specs. This tends to be more expensive (and would guess even more if it were prefinished). If it's quartersawn/rifted, species shouldn't matter.

If not, you would need to find a prefinished hardwood that is approved for radiant heat, and generally that would mean some sort of engineered hardwood. These are generally labeled on the project.

Hope that helps.

Debbie Gartner, aka The Flooring Girl
http://TheFlooringGirl.com
Westchester County, New York

Hi Debbie,

Thanks for your response. We would prefer not to go the unfinished route as we have a large area to do. We have looked at pre-finished engineered hardwood but the problem we run into is that so far, none are guaranteed for temperatures as high as ours. Ideally, rather than searching through every manufacturer for their specs, I would love to find one site that gives guidelines based on the type of wood as a start at least and then we could check with individual manufacturers. Any idea if that type of site exists?

Also, because our pex lines are already installed, we are going to have to glue rather than nail. Any other suggestions you have are welcomed!

Thanks!

Doreen

One hundred is just to high. I doubt any wood manufacturer will warrant this. Why dont you have a temperature regulator on that? Better start looking at tile.

We do have a mixing valve on our system. Our water actually comes in at 160 degrees and we adjust the mixing valve and mix it down to 100. Anything less and we don't get the benefits of the radiant floor heat.

We have looked at tile and would be willing to go that route. The problem with tile is that we have large rooms and tile that looks like hardwood tends to come in 2 foot lengths and that will make the floor look too busy. Any suggestions for porcelain tile that comes in longer lengths and looks like hardwood?

Thanks!

I should have stated that the surface temp should be 85 degrees or less. Thats what most manufacturers recommend.

Check this site; and "test results". http://www.launstein.com/radiant-heating/

Thanks, Stephen. We will check out the site.

Doreen - I would avoid any sort of glue over radiant heat. That tends to cause lots of problems.

This is unfortunate because you have already installed this and partial subfloor...without thinking through what you would put on top as well as installation method. So at this point, you may either be limiting your options and/or may need to redo the subfloor.

So, if you do engineered hardwood, you may want to see if there is a way to nail in (rather than glue) or choose a clickable one that does not require adhesive.

If you do any sort of tile, be sure not to install on top of the 5/8" plywood as the tile will crack. You could do cement board or mud job and/or rip up plywood and then do the same.

I understand you have a large area...but bear in mind, that most of your options will be expensive, no matter what you do.

Debbie Gartner, aka The Flooring Girl
http://TheFlooringGirl.com
Westchester County, New York

Material those have high thermal mass have the ability to store heat for a long time. Examples are some tiles, concrete, many types of stones and earthen floors. Materials those do not have high thermal mass are wood floor, carpet, laminated floor. The reason behind high thermal flooring is that it will emit heat at the desirable rate from the radiant floor system.

I do not understand how having a large ares prevents you from using an unfinished product. Especially if it is the only thing to get the results you need. You can put a layer of luan down and nail (1.5" nails) 3/4 solid (qtr or rift). Then I'd imagine you would have no problems even turning the temperature up if you need to.