Moisture-resistant plywood is a multi-layer sheet, a kind of "layered cake", consisting of perpendicularly laid and glued together wooden sheets (veneer). It is very durable, light enough and versatile. It can be used everywhere - from the construction of aircraft and ships, to the interior decoration of apartments and houses.
Before as buy moisture resistant plywood, let's figure out what it is and what you need to pay attention to when choosing.
Manufacturing material
Most often there are 2 types of wood that are used for the production of plywood: these are birch and conifers (fir, pine, cedar or spruce).
- Birch is a noble material. The color of birch plywood is light, closer to white. It is dense, its strength reaches 30-80 MPa.
- The needles resist moisture better, but they are coarser and contain resin. The color of the coniferous plywood is yellow. It is lightweight and, as a rule, cheaper than birch, its strength index is 25-55 MPa.
- The moisture resistance of both materials is high, but birch is more prone to rotting and the appearance of fungus.
Analyzing the given data, we recommend using birch plywood for flooring, and coniferous plywood for walls and roofs.
Types of plywood
The following types of plywood are distinguished based on the adhesive base:
- FS - average moisture resistance. Adhesive - urea-formaldehyde resin.
- FSF - high moisture resistance. In production, phenol-formaldehyde resins are used.
- FOF - high moisture resistance with additional protection. The composition is the same as that of FSF, but plywood with this marking is laminated on both sides.
Birch plywood is made in all three designs. Coniferous is not suitable for lamination, therefore it is produced only in the FS and FSF types.
Plywood grade
Depending on the quality of the veneer, plywood is divided into 4 grades:
- 1st grade - no defects in material and grinding are allowed during production.
- 2nd grade - a small number of flaws is permissible.
- Grade 3 - knots up to 6 mm are allowed, no more than 10 pieces per 1 m2.
- Grade 4 - defects in sanding and wood quality are not regulated.
Plywood is produced with the same veneer quality on both sides, and with different ones. For example, there is plywood 2/2 - this means its grade is second on both sides. Or maybe 1/4 - this means that one side is front (first grade), and the other is rough (4 grades).
Grinding
Plywood can be sanded on one side (Ш1), on both sides (Ш2), or without grinding at all. Pay attention to the labeling, it is always indicated in the price lists.
Plywood thickness and dimensions
Standard plywood sheets correspond to the following parameters:
- Thickness from 3 mm to 40 mm.
- Width from 1220 mm to 2070 mm.
- Length from 1525 mm to 3000 mm.
Manufacturer country
There are 2 main plywood producing countries on the Russian market: Russia and China. The workmanship is almost the same today.
But note that Chinese manufacturers have begun to use the combined technology more often - this is when the front layers of plywood are made of expensive and high-quality veneer, and the inner layers are made of cheaper ones. Russian manufacturers are guided by GOSTs and use the same materials for all layers.
