information/FAQs

Overlaid plywood

Plywood is often overlaid for protection against weather and wear. A variety of overlay materials can be effectively combined with plywood.

High Density Overlay (HDO) is a layer of phenolic resin impregnated paper that is commonly bonded to plywood in a hot press. It is often used on plywood intended for concrete formwork. This overlay affords considerable face veneer protection as well as smoothness to the poured concrete surface.

Medium Density Overlays (MDO) are usually a layer of phenolic resin impregnated fibrous paper. MDO paper surfaces provide an excellent paint surface, particularly for exterior applications where a high quality paint finish is required. Surface checking is eliminated by the use of this type of overlay. Medium density overlays are bonded permanently to the face veneer during manufacture of the plywood.

Metal Overlays such as stainless and mild steel, aluminium and copper are also applied to plywood. Several specialist manufacturers supply plywood with adhered metal overlays.

Fibreglass Overlays are very compatible with plywood and relatively simple to apply. They have many end use possibilities such as:

Tanks for storing chemicals when resistance of the wood is in doubt;
Liquid storage tanks;
Linings for bins where surface smoothness is a requirement;
Waterproofing structures where abrasion is a factor, such as boat hulls.

A good example of the use of fibreglass overlaid plywood is in plywood containers for shipping.

Fibre Cement Sheet Overlays are particularly important in some applications where the building code requires fire resistance. One way that fire resistance requirements can be met using plywood is by combining plywood with fibre-cement or other acceptable materials.

Decorative Overlays such as vinyl, DAP and melamine have long been available for interior use and many products are available which combine aesthetic appeal, protection against wear, and ease of maintenance.

Lead filled plywood is not strictly an overlaid product. Sheet lead within plywood can be used to provide sound-proof linings or protection from radiation.

Reference: Plywood Association of Australia