Center or stagger floor blocking members?
Tiziano
| Posted in General Questions on
Raised floor
3/4″ Advantech Subfloor
2×12, 24″ OC joists
2×12 blocking every 4′ to provide bearing for the under and subfloor sheathing
3/4″ green treat plywood under sheathing
What’s best for blocking member position?
-If I do stagger the blocking members all of the blocking can be end nailed through the floor joists, but there will be no bearing on the long sides of the sheathing every other 24″.
-If I don’t stagger (i.e. center the blocking every 4′) each sheet has bearing all the way around, but much of the blocking will need to be toenailed to the floor joists.
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Replies
Advantech has tongue-and-groove edges and does not need solid blocking below, unless a licensed engineer specifies it for some reason. With Advantech, which is very stiff, and code-compliant floor joists, blocking isn't needed anyway, unless the spans are long and you don't have something else keeping the joists from rolling under load, which your underside plywood will provide.
If you are using T and G panels for your subfloor, you don't need blocking under the seams (although I personally prefer to have extra support at the seams regardless). I don't see a practical problem with staggered blocking, but I tend to put it all in in a straight line, end nailing one end of each piece and coming in at an angle on the other end. Either way works. If you're most concerned with supporting the edges of the subfloor panels, then I'd put all the blocking in in a straight line and not worry about only being able to end nail one side of each piece.
Bill
Thanks Bill.
The underside sheathing is not T&G but the subfloor sheathing is.
I'll go inline then.
Tiziano,
You can still nail the blocking through the ends when they are are aligned. You just angle the nails a bit.
If the blocking is just to support the plywood seams on the underside, use 2"x4"s on the flat.
I've been in CAD-mode lately with a new project, so easy to make some sketches to help people visualize this stuff. The attached drawing shows how I typically nail in-line blocking when I can only end nail one end of each piece.
Bill