What are the best fastners for a T&G 3/4″ subfloor? I would like to use a glue and screw method rather than nails. It’s an 1890 vintage house and any nailing will loosen up the wood lath and plaster ceiling below.
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Use PL Premium adhesive and #8 Robertson-head (square-drive) coated flooring screws. Wear nitrile gloves while handling the PL Premium; it stains skin permanently.
You didn't mention if this subfloor is going directly onto the joists or on top of another subfloor. If the latter, use 2½" screws and try like heck to make sure you go throught the original subfloor into the joists.
If you're going right onto the joists, use 1½" screws. Put two screws per joist if the boards are 1x6 or wider. One screw per joist is okay for 1x3 or 1x4 t&g.
Ideally, your screw spacing would be on 16" centers, but a lot of older houses have the joists spaced wider (and some of them have very irregular spacing, indicating that the carp laid them out by eye). Do the best you can with what you've got. You can't expect to get a concrete-slab-rigid floor in a 150-year-old, wood-frame house (and who'd want to, anyway?).
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>> any nailing will loosen up the wood lath and plaster ceiling below << Probably would if you are hand nailing. Probably won't if you are using a nail gun. Personally I think ring shank gun nails and lots of subfloor adhesive give very satisfactory results.
QuikDrive or similar is the ticket if you want to screw - they are square drive and the driver is autofeed and allows you to stand up as you screw. Maybe you could rent one. Use 1 3/4" min screws, or 2" are even better.
Whatever you do don't use any kind of drywall screws. Around here we call them Piffiin screws because there is this guy here who goes by the name Piffin and he thinks they are the best thing since sex was invented ;-) Drywall screws are made of pot metal and have virtually no sheer strength.
If you don't want to go the screw gun route, deck screws will work, but just don't get the extra cheap ones.
The attachment schedule for 3/4" T&G sheet subfloor is 6" OC on the supported edges and 12" OC "in the field" (center of the sheets).