Waterproof plywood: dimensions, characteristics, properties, application area
Waterproof wood panels made of veneer are considered to be the most popular in concrete construction, interior and exterior finishing, decorating. Plywood has moisture resistant properties due to the adhesives based on synthetic resins, which are used to glue the sheets. At the same time film faced plywood is also very popular in the construction industry. This waterproof plywood has improved water-resistant properties and specific scope of application.
Waterproof plywood: features of the material
This sheet material consists of veneer of deciduous (most often birch) or coniferous trees, peeled according to a certain technology. Initially, natural resins contained in the raw material determine the level of its moisture resistance. Hardwoods have better protection from moisture penetration than conifers, so hardwoods are more polular for exterior works, while conifers for interior applications.
The use of synthetic adhesives increases resistance to moisture and allows getting waterproof plywood as a result. The following types of glue are used for treatment:
1. Urea-formaldehyde adhesive - the limit of water resistance is 5-12%. Materials based on them do not withstand continuous exposure to moisture, so the use of such waterproof plywood is limited to interior decoration with average humidity. Plywood sheets of this type are produced in Russia under the brand name FK - moisture resistant plywood (MR Grade).
2. Phenol-formaldehyde adhesive – water resistance is 12-17% due to the use of synthetic resins. The substance has good binding and waterproof properties. It is often used for exterior decoration, but it can also be used indoors, for arrangement of moisture-resistant structures. Such material is produced under the brand name FSF – weather and boil proof plywood (WBP Grade).
The strength characteristics and moisture resistance of film faced plywood depend on the type of protective coating. Lamination technology provides the product with features that are not typical for wood, but at the same time plywood preserves the natural structure of wood. This material has wide application in concrete construction; it is used in furniture industry and design. Its brand name in Russia is FOF.
Film faced, waterproof plywood is made on the basis of exterior plywood panels, veneer is glued with phenol-formaldehyde resin. Thus, it is classified as a durable material even without overlay. The characteristics and features of film faced, waterproof plywood depend on the type of film:
- phenolic film - the paper is impregnated with phenol-formaldehyde resin which is, in fact, waterproof compound. Such plywood is used for exterior works, formwork manufacture, cladding of front faces, etc;
- melamine film - waterproof substance. Melamine film faced plywood is often used for interior decoration where the materials withstanding high humidity are necessary.
In addition, the characteristics and features of moisture-proof, film faced plywood depend on the texture type of the protective coating: SP - for painting, F - smooth, W - wire-mesh.
Areas of waterproof plywood application:
- interior works. MR grade (moisture resistant) plywood is used for interior works. It is less resistant to water, but it holds heat and absorbs noise, it is easily processed. Urea-formaldehyde resin treatment increases water resistance of plywood for internal use;
- exterior works. Sheets of birch plywood are used for exterior works. They are more resistant to moisture, easily processed, and do not become deformed. Phenol-formaldehyde resins are used for treatment. The dimensions of waterproof plywood for facade finishing and external structures vary in thickness from 4 to 40 mm. The most common sizes are 1220 x 2440, 1250 x 1250 mm or 1500 x 3000;
- formwork systems.The basis of the material is usually birch veneer. Standard thicknesses of the sheets of waterproof plywood for this application are 15 to 35 mm, standard sizes are 2440 x 1220, 2500 x 1250, 3000 x 1500 mm.
Review Birch Plywood