When it comes to sheet materials for construction, DIY projects, and furniture building, Oriented Strand Board (OSB) and plywood stand out as two popular choices. While both serve similar purposes, they have distinct features and applications that make them suitable for different projects. Let’s dive into the pros and cons of OSB and plywood to help homeowners, builders, and crafters in the UK make informed decisions.
Key Features:
| Question | Plywood | OSB |
|---|---|---|
| What is it made of? | Thin sheets of wood glued together with alternating grain directions. | Wood strands oriented in perpendicular directions and glued together. |
| Strengths | Strong, durable, versatile, moisture-resistant. | Strong, lightweight, cost-effective, moisture-resistant. |
| Weaknesses | Can be expensive, difficult to work with unsupported. | Not as strong as plywood, can be damaged by moisture if not sealed properly. |
| Typical uses | Furniture, flooring, cabinetry, roofing, siding, subflooring. | Subflooring, roofing, siding, furniture, cabinetry. |
| Weight | Heavier than OSB. | Lighter than plywood. |
| Waterproof | Moisture-resistant but not waterproof. | More moisture-resistant than plywood but not waterproof. |
| Cost | Can be more expensive than OSB. | Generally less expensive than plywood. |
What is OSB?
OSB, or oriented strand board, is a structural wood panel made from shredded wood chips and adhesive resin. These wood strands are oriented lengthwise to provide strength and stiffness. Introduced to the UK market in the 1980s as a cost-effective alternative to plywood, OSB is widely used in flooring, wall sheathing, roofing, and other construction applications.
Advantages of OSB:
- Affordable: OSB sheets typically cost 15-30% less than equivalent plywood panels, making them economical for large projects.
- Structurally Strong: Oriented wood strands provide excellent strength, stiffness, and load-bearing capabilities along the panel’s length.
- Workable: OSB is easy to cut, drill, shape, and fasten using standard woodworking tools.
- Water Resistant: Modern adhesives make OSB highly resistant to delamination and deterioration when exposed to moisture.
- Range of Grades: Available in grades 1 to 4, allowing for matching strength and quality to the application.
Disadvantages of OSB:
- Not Moisture Proof: OSB can swell, warp, and lose strength if exposed to prolonged wetting.
- Weaker Across Width: Less stiffness across the panel compared to plywood may require additional bracing for some applications.
- Prone to Damage: Unprotected OSB edges are easily damaged during transport and installation, requiring careful handling.
- Contains Formaldehyde: Some grades of OSB contain urea-formaldehyde resin, which may irritate eyes and airways during cutting and sanding.
- Rough Appearance: OSB’s patchwork appearance makes it unsuitable for exposed decorative surfaces in many applications.
What is Plywood?
Plywood consists of thin sheets of wood veneer glued together in alternating grain directions, providing strength, stability, and resistance to cracks and splits. It comes in various sizes and grades, with options for exterior use and different wood species.
Advantages of Plywood:
- Strong and Stiff: Crossband veneer layers make plywood rigid and able to span gaps without sagging, with excellent screw and nail retention strength.
- Dimensionally Stable: Resists warping, twisting, and buckling better than solid wood, maintaining its shape over the long term.
- Attractive Appearance: Layered veneers create an appealing pattern on panel edges, with better grades featuring knot-free faces and real wood textures.
- Moisture Resistant: Exterior plywood can withstand exposure to rain and damp conditions when properly sealed and finished.
- Range of Types: Many varieties available including hardwood, softwood, marine grade, treated, fire retardant, and more.
Disadvantages of Plywood:
- Cost: Good quality plywood is significantly more expensive than OSB and other wood composite panels, with higher prices for appearance grades.
- Heavy and Bulky: Plywood weighs more than OSB, making large sheets awkward and difficult to handle and transport.
- Prone to Delamination: Can separate at the plies when subjected to excessive moisture over time, requiring careful selection and maintenance.
- Unsuitable for All Uses: While strong, plywood lacks the structural stiffness of OSB for some applications like subfloors and wall sheathing.
- Voids and Defects: Lower grades may allow knots, patches, and gaps, interrupting appearance and strength.
Choosing Between OSB and Plywood:
When deciding between OSB and plywood, consider the following factors:
- Subfloors: OSB is ideal for stiff, strong, and economical subflooring, while plywood may require additional support to prevent squeaking.
- Wall Sheathing: Both OSB and plywood perform well, with OSB being cheaper but requiring moisture-resistant grades and protection from direct water exposure.
- Roof Sheathing: OSB is preferred for cost savings, but stiffer plywood minimizes