Exposure 1
Exposure 1 is a plywood adhesive classification indicating the panel uses waterproof glue that will not fail from moisture, but the panel is designed for temporary construction moisture exposure — not permanent outdoor use.
In Detail
Exposure 1 Classification
Exposure 1 is one of four adhesive durability classifications defined in PS 1-09 for structural plywood. It means the glue bond is fully waterproof (identical phenolic resin used in Exterior-rated panels), but the panel as a whole is rated only for temporary construction moisture exposure.
The distinction matters: an Exposure 1 panel uses waterproof glue, but its inner veneers may be D-grade (with voids) that are not suitable for permanent weather exposure. An "Exterior" rated panel uses both waterproof glue AND C-grade or better veneers throughout that can tolerate permanent outdoor use.
In practice, Exposure 1 plywood (like CDX) handles construction-phase rain without delaminating. But if left permanently exposed to weather — as outdoor siding, for example — the D-grade veneers will degrade even though the glue bond remains intact.
Related Terms
CDX Grade
CDX is a plywood grade designation meaning C-grade face veneer, D-grade back veneer, and Exposure 1 (X) adhesive — the most common structural plywood grade used in residential construction for roof sheathing, wall sheathing, and subflooring.
Veneer Grade
Veneer grade is the quality classification of individual wood plies in plywood, ranging from A (smooth, paintable, minimal defects) to D (interior use only, knotholes up to 2-1/2" permitted), as defined by PS 1-09.
Delamination
Delamination is the separation of bonded layers in a laminated material — in plywood, it means the adhesive bond between veneer plies has failed, causing the plies to separate and compromising the panel's structural integrity.