Do I need a nailing edge around the perimeter of the room for the new AdvanTech subfloor

blockingjoistssubfloor

I have torn out the original flooring from by 1910 Victorian so that I can level the joists and install new sound subfloor. I'm using 3/4" AdvanTech T&G subfloor, glued and screwed to the new sisters.

What I'd like to know is if I need to install blocking to provide a nailing edge around the perimeter of the room where the joists deadhead into the brick walls. The original floor had no nailing edge. Installing blocking will be pretty easy in some places, but there are mechanicals that make installing it a challenge in others. There are places where I can't fit a nailing edge within 6" of the exterior wall.

Nailing Edge Here?

Some things I'd like opinions on are:

  1. If I don't install a nailing edge, is it likely I will have a noticeable bounce?
  2. If I should install a nailing edge, but can't fit a full height joist in place, will a 2×4 add enough rigidity to be worth the energy to install?
  3. If I should install a nailing edge, but can't get one within a few inches of the exterior wall, do I just install one as close as possible or is that just a waste?
  4. What would your typical contractor do in this scenario?

For you old house lovers who want to yell at me for chucking the old growth pine planks, please know that I did everything I could to try to salvage the original floor. For a wide variety of reasons, it just wasn't in the cards.

Update: Just as an FYI I did not install blocking around the perimeter. 5 months later and there is no noticeable difference between the rigidity of the floor system between the middle of the room and the perimeter. Thanks for you help!

Best Answer

If I don't install a nailing edge, is it likely I will have a noticeable bounce?

No, because you can't stand that close to the wall. The only unsupported edge is right at the face of the wall

If I should install a nailing edge, but can't fit a full height joist in place, will a 2x4 add enough rigidity to be worth the energy to install?

Yes. A 2x4 is more than adequate for that span and use

If I should install a nailing edge, but can't get one within a few inches of the exterior wall, do I just install one as close as possible or is that just a waste?

Close as possible is adequate. Think about how much plywood can bend if you wanted to bend it at say 4" in from the edge, almost impossible

What would your typical contractor do in this scenario?

When I was a contractor I would usually not worry about it. 3/4" ply is very stiff (and rated for 24" oc) and as I noted, no one can stand close the wall anyway. If it were to be a tile floor, I might be more likely to add it since tile is so sensitive. I would consider that adding blocking would reduce air flow at the exterior wall in the crawlspace and therefore increase humidity and likely of decay or mold issues.

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