MDO vs HDO Plywood: Overlay Types for Outdoors

Engineered Exterior Overlays

Medium Density Overlay (MDO) and High Density Overlay (HDO) are specialized plywood products. Instead of wood veneers on the surface, they feature resin-treated fiber overlays heat-pressed onto the core.

1. Medium Density Overlay (MDO)

• Surface: Smooth, matte paper-like fiber overlay.
• Best feature: The absolute best paint-holding surface of any wood product. The overlay prevents the wood grain from checking or lifting over years of outdoor exposure.
• Common uses: Outdoor signs, highway billboards, cabinet structures.

2. High Density Overlay (HDO)

• Surface: Semi-gloss, hard plastic-like resin overlay.
• Best feature: Water-resistant and extremely wear-resistant. The surface is slick and acts as a release liner.
• Common uses: Concrete forming (reusable up to 50 times), heavy-duty industrial shelving.