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Air sealing 2×6 subfloor

kewilso3 | Posted in Energy Efficiency and Durability on

I’d like to use 2×6 T+G boards as my subfloor and finished floor. Single story home, 28×48 rectangle. Air barrier will be exterior sheathing, over a sealed crawlspace. Cavity insulation in the walls, and rigid foam on the interior of the crawlspace.

Current plan is to install the boards in the same sequence/position as a typical plywood subfloor, on top of the band joist/ under the bottom plate. Would there be any additional air sealing concerns with this technique, or would I just run the sheathing  over on the outside and be good?

Also would like to hear any tips for keeping this finished floor in decent shape through the rest of construction.


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  1. walta100 | | #1

    It sounds like your plan is to have a conditioned crawl space if so the floor is not your air barrier. If the floors leak it simply doesn’t matter.


  2. walta100 | | #2

    Note the wood sold today as pine is not likely to be as dense as the old growth pine flooring from a hundred years ago. The toenail of most dogs will dent today’s pine and crack any film finish you have applied. Bar stool legs and high heels will also be a problem. Make a 3 foot square sample and test it with high heels.


    1. kewilso3 | | #4

      Yes thank you. Some places still sell heart pine with more dense growth rings, and some places have reclaim but it's so expensive that the appeal is lost for me. I'm trying to determine if the YP will be hard enough. Hard to find a good source since most people commenting on it are selling it, so a sample may be my best bet.

      1. walta100 | | #6

        In my opinion construction grade pine would with a standard finish would quickly be a mess in most homes.

        We almost bought a home with soft pine wood floors. The owner had large dogs the floors needed refinishing every other year and looked bad. You could see dents from people sitting on the bar stools and drag marks from moving furniture.

        That is not to say someone with a different lifestyle couldn’t keep them nice.

        Build a test floor and test it out. Consider avoiding a film finish like polyurethanes and varnish’s and look at a walnut oil finish.

  3. Expert Member
    Michael Maines | | #3

    Be sure the T+G is dry. I've seen a lot of them open up over time; the tongues on 2x6 material are usually quite short.

    As long as your crawlspace is air-sealed, insulated and dry, I see no problem with your approach. You do need to condition the crawlspace with heat and possibly a dehumidifier.

    The typical approach for protecting floors these days is Ramboard or a similar heavy-duty paper product. If you want more impact resistance you can add a layer of Masonite or Luan plywood. In fact, in the "old days" before Ramboard was available, I did many renovations using a layer of rosin paper topped with Masonite, with the seams taped with duct tape. Rosin paper's red coloring will bleed into the flooring if it gets wet, though, so either Ramboard or kraft paper would be a better bottom layer. If you're planning to sand the flooring after construction, you could skip the paper layer.

    1. kewilso3 | | #5

      Thanks Michael, that brings up another point I've been mulling over. For a typical wood flooring install, the ideal scenario is to bring the flooring into the conditioned space and allow it to acclimate. When the subfloor is the finished floor, it will obviously be installed well before the space is conditioned. So is my best bet just to make sure everything is dry, and maybe try to install on a room temperature day if possible?

      1. Expert Member
        MALCOLM TAYLOR | | #7


        Acclimatizing to the house during construction is a problem because those humidity levels don't reflect what will occur once the house is complete. You are better off getting the wood to the desired moisture levels before installing it. This article explains what is in play:

  4. Expert Member
    Akos | | #8

    I built a loft using 2x6 t&g in my home. It definitely does not hold up well, even with minimal traffic there it has gotten pretty banged up. I can't imagine what it would look like in a high traffic area.

    Durability aside, my bigger beef is squeaks. I've tried many things including re-laying the floor twice with different edge treatments and I could not get it not to creak. My best guess is the issue with water based clear coats as it tends to stick to itself causing the noise when the boards move.

    Overall, not something I would do again.

  5. andy_ | | #9

    I'd be wary of having what will be a finished surface present so early in the building process. Framing over subfloor dings it up quite a bit. Bracing blocks get nailed to it, notes and lines snapped all over the place, partition walls built on the deck and then dragged and lifted...all of it happens on what is arguably a more durable surface of 3/4 subfloor. How is soft pine going to hold up to that abuse, not to mention weather while framing the house?

    1. kewilso3 | | #10

      I believe I've been talked out of this idea. I've come across it several times and really like the concept as it removes a step in the process and avoids sheet goods, but the tradeoffs don't seem worth it the more I learn. If the available 2x6 T+G woods were harder, it might be worth it. Or, if I were building a rustic cabin.

      If going this route I would frame the house as well so that I could control the process much better, but I am thinking it introduces more obstacles than it relieves

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