What is the difference between Exposure 1 and Exterior rated panels?

Exposure 1 panels are designed to withstand moisture during the construction cycle, while Exterior rated panels are built for permanent exposure to the elements.

Can I install T&G panels parallel to the joists?

No, panels must be installed perpendicular to the joists to ensure structural stability and meet code requirements.

Why do I need to leave a gap at the panel ends?

A 1/8 inch gap is required to allow for expansion due to changes in humidity, preventing buckling.

Is construction adhesive mandatory for subfloors?

While some localized building codes vary, the use of APA-approved construction adhesive is strongly recommended to minimize floor squeaking and increase system stiffness.

Tongue & Groove Subfloor PanelsGenerating image…

Plywood & Sheathing

Sheathing

$35.00 to $65.00 per 4x8 sheet (2026 average market estimates).

Tongue & Groove Subfloor Panels (2026)

Prepared by Lumberama's Building Materials Team

|Last updated September 3, 2026|Sources & methodology

Tongue and groove (T&G) subfloor panels are engineered structural wood products designed to provide a continuous, stable surface for finished flooring. Manufactured primarily from OSB or plywood, these panels feature a precision-machined profile on the long edges to ensure tight interlocking, which minimizes vertical differential movement between adjacent sheets and supports load distribution across joist systems.

Key Features

APA-rated structural performance. - Machined tongue-and-groove profile for edge alignment. - Moisture-resistant resins (Exposure 1). - Dimensional stability. - Uniform panel thickness.

Specifications

Typical Thicknesses: 23/32 inch (often labeled 3/4 inch nominal) and 7/8 inch. - Standard Sheet Size: 4 ft x 8 ft. - Panel Grade: Rated Sturd-I-Floor. - Exposure Rating: Exposure 1 (suitable for temporary moisture exposure during construction). - Common Span Ratings: 20 oc

24 oc

32 oc

and 48 oc.

Applications

Residential subfloor systems over wood joists. - Light commercial flooring platforms. - Substrate for hardwood
tile
carpet
or laminate underlayment. - Elevated interior deck surfaces.

Installation Overview

- Install panels with the long dimension perpendicular to floor joists. - Stagger end joints at least two joist spaces apart. - Maintain a 1/8 inch gap at all panel ends for thermal expansion. - Apply construction adhesive to the top of joists to prevent floor squeaks. - Align tongue and groove edges tightly; do not force fit.

Pros & Cons

Pros

✓ Reduces differential movement between panels. - Eliminates the need for blocking on joist bays. - Faster installation speed compared to square-edge panels. - High structural load capacity.

Cons

✗ Requires careful storage to prevent moisture-induced swelling. - T&G edges can be damaged during rough handling. - Slightly higher cost than square-edge sheathing.

Code Requirements

- Must bear the APA-EWS (Engineered Wood Systems) trademark. - Span rating must meet the IBC/IRC structural load requirements for the specific joist spacing. - Fastening Schedule: Typically 8d common nails or equivalent screws, spaced 6 inches apart on edges and 12 inches apart on intermediate supports.

Buying Tips

- Verify the APA stamp for 'Exposure 1' rating. - Inspect tongue integrity prior to installation to ensure smooth fit. - Confirm panel thickness matches the design load requirements. - Store flat and off the ground to prevent warping.