Plywood is a versatile material that combines an attractive surface appearance with excellent strength. It is available in various wood species, both hardwood and softwood, and with a range of different adhesives, depending on the application – exterior or interior. Plywood provides dimensional stability and good strength both along and across the panel.
Depending on the thickness and intended use, plywood consists of several or a dozen odd-numbered sheets of veneer laid at right angles to each other, creating a very stable and strong end product, mainly in dimensions of 1250 x 2500 mm. Plywood is made from softwood (pine, spruce) or hardwood (birch, alder, beech, poplar or exotic species). The type of wood used on the surface determines whether it is classified as a particular type.
Plywood is widely used in the furniture, packaging and transport industries, as well as in construction, which is of particular interest to us.
In timber construction, plywood is used as a substrate for facade cladding and for some roof coverings. In light timber frame construction, plywood can be used as sheathing for floors, walls, and roofs. In this respect, plywood is the prototype for its cheaper and inferior competitors in terms of strength parameters: OSB or MFP boards.
Both plywood and chipboard, including OSB, have advantages and disadvantages. It is worth getting to know them so that you can make the right decision in the future.
Many people may wonder which product is more resistant to moisture. In this respect, plywood is definitely superior to OSB, allowing the building to “breathe” by absorbing and releasing water vapor while remaining resistant to moisture and longer resistant to mold and fungi.
When exposed to moisture and water, OSB swells, especially at the edges of the panels. Swelling is generally greater than in plywood due to the release of compressive stresses in OSB caused by the pressing of wood chips into panels. Swelling of the edges of floor sheathing boards can cause the floor layers to rise and affect tiles or carpet. Swollen edges may be visible on the roof sheathing when asphalt shingles are installed. The edges of plywood can also swell when exposed to moisture or water. However, they tend to return to their nominal thickness after drying and retain their physical and mechanical properties, while OSB boards remain permanently swollen to some extent.
Surprisingly, both boards are vapor-permeable. According to the Panel Guide, the vapor permeability of OSB boards, depending on conditions, is 30 for humid conditions and 50 for dry conditions. The publication does not specify whether this is the vapor permeability for OSB/2, OSB/3 or OSB/4 boards.
The water vapor permeability of plywood, according to the aforementioned Panel Guide, varies depending on its type, density, and structure. In humid conditions, this coefficient ranged from 50 to 110, while in dry conditions it ranged from 150 to 250.
Plywood manufactured by Paged Morąg has similar properties, with vapor permeability ranging from 70 in humid conditions to 220 in dry conditions, depending on the type, density, and structure of the plywood.
In frame construction, wood-based panels are used as sheathing for floors, walls, and roofs. In this application, they stiffen the building structure and serve as a substrate for finishing materials – facade cladding and roof covering.
Due to its three-layer structure, OSB boards must be installed with their longitudinal axis perpendicular to the floor joists or roof rafters.
This requirement does not apply to plywood; the layered, perpendicular veneer structure allows the plywood to be laid in any direction on floor joists or rafters. This saves time during installation and dimensional processing. These requirements do not apply to wall sheathing; OSB boards and plywood can be laid in any way.
Both boards are subject to expansion in length and width when exposed to moisture. Taking the above into account, when installing boards on floor, wall and roof sheathing, a gap of approx. 3 mm should be left between the boards, which will allow the boards to expand under the influence of moisture without bulging at the edges and the possible consequences thereof. Remember that OSB boards will not return to their original shape on their own, but plywood will.
This is, in short, one major advantage of plywood over OSB boards. This is not a suggestion to never use OSB, but it is recommended to take all variables into account and ensure that the wall components as a whole do not trap moisture inside. Another important factor is that plywood is a versatile material that can be used in many industries.
We offer wholesale plywood, available exclusively in large quantities, such as pallets, trucks, sea containers, and rail containers. We invite you to familiarize yourself with our offer and find the perfect solution for your needs. Contact our sales department for more information – we look forward to your inquiries!
