Hi,

We recently finished the lower level in our 1959 Craftsman style home and installed radiant heat in a 6" concrete slab. On top of this we had planned to install bamboo. However, our neighbors up the street decided to replace the floor in their great room. It was much cheaper for them to put in a brand new floor than to repair the existing one so they planned to rip out the old one and get rid of it. It was 3/4" solid mahogony from 1911 (it's stamped on the back) and so I asked if I could take it out with the possibility of recycling it. They loved the idea since it saved them money and so I spent a couple days carefully taking out the flooring. I now have about 700 sq ft of 3/4" tongue & groove mahogony flooring that I'd love to install in a master bedroom, walk-in closet and library area. I have several questions on how to go about this and welcome any information or feedback you can provide.

We floated 3/4" t&g OSB in master bedroom and walk-in closet to give us something to nail into. I've been looking through old threads and articles and while that is an option it's down on the list. Since we haven't installed any of the flooring yet it would be relatively easy to put 1/4" plywood on top of the OSB or even replace it. Will the 3/4" OSB have the strength to hold the nails and keep the flooring in place?

One of the biggest questions I've been thinking about is how to refinish the flooring. Since they were planning to replace the floor, they didn't cover it during the renovations and the floor is covered with gunk - paint, plaster, etc. The wood was also stained a very dark color and some the stain went down into the cracks and hardened on the edges of the strips.

I have a friend with a disc sander and we've put some of the flooring through it taking off 1/16" and it looks great! However, I'm wondering if we really should be doing this. Perhaps it's better to just scrape the edges and get the floor laid down and then rent one of the big drum sanders?

Lastly, I've been wondering what I should use to seal/stain the floor? I was thinking to use an oil based polyurethane.

Thanks for your time!
Dan

I think if you add 1/2 inch ply on top of the OSB your subfloor would be fine. Offset the sheets so you are creating a room size plywood base and fasten the new floor to that.
As far as sanding the old mahogany, go to a box store and buy a cheap thickness planer and run the floor through that before installing. Spending a couple hundred bucks at that point will save a lot of sanding later, plus allow you to see the graining and colour of the individual pieces before installing them.
Sell the planer afterward if you wont need it again. I suppose you could also rent one, but that would probably cost as much or more than buying one.

Hi Dennis,

Thanks for the reply!

The boards we ran through the sander looked good, is there a reason you are suggesting we switch to a thickness planer? I was worried that taking material off before putting the floor down was a waste because the floor would need to be sanded down again with the drum sander. I wasn't sure all the effort was worth it; especially, since we're losing 1/32" of the hardwood floor. It's the same amount of work to run the flooring through a thickness planer, and like you said, I can always sell it when I'm done, but I was wondering why you thought it was a better option?

Also, would 1/4" plywood be enough to give the nails something to bite into Perhaps if I used 1/4" and staples? I don't want my subfloor to get too thick, if I can help it.

Thanks again,
Dan

1/4 inch plywood will be sufficient, but switch to 1 3/4 inch cleats rather than 2 inch.
Well I was thinking about the thickness planer for speed more than anything else. I misinterpreted the type of sander you were using; figured it was a little hand held unit.

hire/buy a router to clean off the tongue, just be careful.

I believe that's a no-no to install a 3/4 solid over in-floor radiant heating.... unless I'm not reading this thread correctly........ which is entirely possible

Well I think, given that this floor has already been installed for nearly one hundred years, it isnt going to move too much over a double layer of sub-floor, not to mention that mahogany is pretty up there on the stability scale. This is one of those out of the box situations that sometimes comes up.

I have seen 3/4 solids crown over in-floor heating. The tubing was underneath 3/4 advantech and stapled to the joisting about 1" below the subfloor. Carry on....

Hi,

I've looked over a lot of literature on radiant heat and once the concrete has fully cured it loves hardwood flooring. That's because the underlayments and floor itself transfers heat very well. I've never seen any warnings about installing a specific type of hardwood flooring so the concern over installing 3/4" solid hardwood flooring over radiant heat is new to me. I have seen plenty of warnings about hardwood flooring and moisture, though they would seem to apply to all hardwood flooring types, not just 3/4". What is the specific concern about 3/4" solid hardwoods over radiant heat?

The 3/4" OSB subfloor floats on a concrete slab but there are are some areas where the subfloor isn't flat. In those areas I am considering screwing the OSB to the concrete slab with concrete screws. Then, to take out any dips or valleys in the flooring, I was thinking to use a self-leveling compound between the 3/4" OSB and 1/4" plywood. Does this seem like a reasonable thing to do?

I've been doing quite a bit of research on installing hardwood flooring and it's more involved than at first glance. At first I had planned to have the floor installed but the quotes came back around $5,000 and that didn't include any work on the subfloor. Also, that was for only the Master bedroom, walk-in and hallway, about 375 sq ft. It's kind of ridiculous, but contractors go past the golf course on the way to my house and their prices double or triple. The last flooring contractor to give me a quote had done work for a friend of mine at $20hr. He'd done almost all of the flooring in my friends house over a period of about a week and 1/2 and done a pretty nice job. When he arrived at my house, he wanted $100 hr. I don't mind paying a fair price for good craftsmanship but getting gouged isn't my style.

After all my research I am seriously considering installing and finishing the floor but having a professional sand it down for me. Does anyone know someone who does great work and is willing to work in the 94566 area code? I've had some real duds for contractors and would like to avoid that with this flooring project.

Thanks!
Dan

Im thinking that screwing into a concrete slab with imbedded radiant heat tubes is less than a steller idea.
And I cannot imagine anyone keeping a straight face while saying he is worth 5000 bucks to just install 375 square feet of flooring.
However, regardless of the "book"; given all the circumstances about your project I still maintain that there should be little if any problems with your install. This is not to say that anyone can install any 3/4 inch hardwood over any radiant heat system. Just for your application, it seems fine.

Hi Dennis,

When installing the concrete slab we put in a 3/8" rebar mesh on top of 1 1/2" adobe blocks. We tied the tubing to this mesh and poured a 6" slab. That means that from the top of the concrete, the tubing is down a good 3". From the top of the OSB, the tubing is down over 3 3/4". I don't think using 2" concrete screws is that great of a risk, though as you mention, there is some small possibility that the mesh got moved up in places during the pour.

What would be your recommendation on getting the floor flat? One of the contractors that came through said he'd seen and installed over much worse. That when the flooring was installed there would still be a small soft spot but he wasn't too concerned about it. I'd rather not have soft spots.

Thanks,
Dan