We are replacing part of a bathroom floor along side a non support wall.
This is because the floor was not installed level and also suffered water
damage. The carpenter said we should put blocking under the wall between
joists since we will be cutting the plywood subfloor next to it and the wall
might eventually sag without the blocking. I certainly agree. The question
I have is should the plywood be just laid and nailed on top of the blocking
or should we add blocking perpendicular and between those first blocks so
the cut edge of the plywood has something to sit on. Thanks for your
Even in new construction w/ T&G or not the edges of subflooring (that
_is_ what you're talking about, right?) are not "left hanging" between
joists in any reasonable construction--the sheets are trimmed to meet on
If your retrofit can't cut back to an existing joist for some reason,
then certainly there should be blocking at the joint(s) of adjacent
sheets to avoid the otherwise inevitable springiness that a cantilevered
sheet edge would otherwise be. It seems unlikely in most cases one
couldn't simply go back to the next joist, however.
If you're talking cross-joists and not with the joist direction, then
you're only talking a 16" span and probably can get by, but if there's
access to insert blocking, can't hurt and can't cost much.
imo, ymmv, $0.02, etc., etc., ...
The more edges you tie together in floors, walls, whatever, the
stronger the structure will be. Applies to drywall, too. Your
intuition on this one is absolutely correct. Keep in mind that
construction adhesives add tremendously to overall quality and that is
why more and more quality homes are being litertally glued together
thse days. HTH
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