Laying 3/4 T&G subfloor over 2x10s at 16 on center.

Subfloor Installation Guide: 3/4" T&G over 2x10 @ 16" OC

1. Prep the Joists

• Inspect joists for damage, level them. Shim or plane high spots.
• Ensure 2x10 depth is consistent (actual ~9.25").

2. Acclimate Subfloor

• Store plywood in the space 48+ hours. MC should be 6-12%.

3. Layout

• Start at one corner, leave 1/4" gap to walls (use spacers).
• Stagger end joints ≥2 joist bays.
• Face the good side up (less sanding needed).

4. Fastening

• Use 2½" #10 or 12d screws (not nails) every 6" along edges, 12" in field.
• Keep screws 3/8" from panel edges, 1/4" from end joints.
• Drive flush—don’t over-sink.

5. Tongue & Groove

• Orient T&G direction perpendicular to joists.
• Use a T&G flooring clamp or pull the panel tight with a pry bar.
• Apply a dab of construction adhesive in the groove before mating (optional but reduces squeaks).

6. Prevent Squeaks

• Screw into joists only—avoid overhangs.
• Use construction adhesive on joist tops before laying (reduces movement).

7. Prevent Humps

• Check each sheet for flatness before fastening.
• Sand minor high spots or use a belt sander.
• Don’t trap moisture—ensure ventilation.

8. Final Check

• Walk over and tighten any loose screws.
• Fill screw holes if needed before finished flooring.

Code Note: Per IRC R502.3.1, 3/4" subfloor is acceptable for 16" OC joist spacing.

Done right, this subfloor will stay flat and quiet.

Fast, Quiet, Flat Subfloor — 3/4″ T&G on 2×10 @ 16″ OC

1. Check joists first - Crown every joist up. Snap a chalk line; plane or shim high spots > 1/8″ in 8 ft. - Blocking: solid 2×10 blocking at 8 ft max (mid-span if > 16 ft span). Nail 3-16d each end. IRC R502.7.1

1. Layout - Start with a full sheet groove-side on the wall. Leave 1/8″ gap at walls (expansion). - Stagger end joints ≥ 2 ft; keep them over joists. - Snap lines every 4 ft to keep rows straight.

1. Adhesive + Fasteners (the anti-squeak combo) - Subfloor adhesive: ASTM D3498 (e.g., PL400, Titebond 816). Run two continuous 3/8″ beads on each joist — one near each edge of the panel. - Fasteners: 2″ ring-shank nails (0.113″) or #8×2″ coarse-thread screws. - Field: 12″ OC - Edges: 6″ OC, 3/8″ from panel edge - IRC R503.2.2.1 / ESR-1539 - Drive flush — don’t countersink; it crushes glue bead.

1. T&G engagement - Tap with block and sledge — don’t jump on it. - If gap > 1/32″ after tapping, pull up, add glue, re-seat.

1. Immediate cleanup - Wipe squeeze-out wet. Dried glue = telegraphing humps.

1. Protect - Cover with breathable paper (not plastic) if trades follow. No wheelbarrows, pallets, or concentrated loads until walls/sheathing stiffen the diaphragm.

Red flags

• Joist span > 16 ft? Verify deflection (L/360 live). Sister or add mid-span beam.
• OSB vs plywood? Same rules — but OSB swells more; keep dry.
• Radiant heat? Use 1-1/8″ T&G, 6″ OC edges, and adhesive rated for heat.

Bottom line: Glue every joist, ring-shank every 6″/12″, crown up, block mid-span. That floor won’t move.