Subfloor thickness is not a preference, it is a function of joist spacing. Get that pairing wrong and the floor is springy no matter how much glue went down.
Panels run perpendicular to the joists, with end joints staggered.
Glue is what stops squeaks. A squeak is the panel working against a fastener, and adhesive removes the movement.
Subfloor panels carry a span rating, and it is the joist spacing that determines what you need — not preference, and not what happens to be on the rack.
| Joist spacing | Minimum | Practical choice |
|---|---|---|
| 12″ o.c. | 19/32″ | 19/32″ |
| 16″ o.c. | 19/32″ | 23/32″ |
| 19.2″ o.c. | 23/32″ | 23/32″ |
| 24″ o.c. | 7/8″ | 7/8″ or 1″ |
Minimum is what the rating allows. Practical is what feels solid underfoot, and the gap between them is most of the difference between a floor people compliment and one they mention.
Tile is stricter again. Stone and ceramic crack at deflections a carpeted floor would never notice, which is why tile assemblies usually want a thicker subfloor plus an underlayment or membrane over it.
A squeak is a panel moving against a fastener. Fasteners alone cannot prevent that forever, because wood shrinks as it dries and the hold loosens.
Construction adhesive between joist and panel makes the two act as one. It stops the movement, and it genuinely stiffens the floor because the assembly becomes composite rather than two layers rubbing.
One 28 oz tube runs roughly 25 to 30 lf of joist at a ¼″ bead. Lay only as much as you can cover before it skins.
Panels run perpendicular to the joists so the long dimension crosses as many supports as possible. End joints stagger, so no joist line carries every seam.
Tongue and groove edges go on the long unsupported edges, which is where the panel would otherwise flex relative to its neighbour. Square-edge panels need blocking under those edges instead, which is more work than buying T&G.
About 45–50 on a 4×8 at 16″ o.c. — 6″ at edges, 12″ in the field. More than people expect, and edge fastening is where squeaks start.
Ring shank nails are fast and code-accepted. Screws hold better against withdrawal and are worth it over glue. Smooth shank nails are not appropriate for subfloor.
Yes — about 1/8″ at ends and edges. Panels absorb moisture and expand, and butted tight they buckle at the seams.