Green Building Topics

Green Building Materials Guide

WOOD PANELS: Plywood, OSB, MDF, and Ag Waste Boards

This guide explains environmental considerations with the most common types of wood panels. Application-specific information is also available in the following guides: Sheathing, Concrete formwork, Structural Insulating Panels, and Gypsum Board.

Considerations:

Consider reusing salvaged or reclaimed panels.
For new panels, use FSC certified products.
Consider structural insulating panel (SIP) construction, which provides interior and exterior sheathing, excellent insulation, and comes in pre-cut panels for rapid assembly.
For wood-frame construction, determine whether bracing could be used to eliminate the need for structural sheathing. In appropriate designs, non-structural grade sheathing can enhance insulation and reduce wood requirements, particularly when recycled or non-wood fibers are used.
Use exterior-grade plywood for interior applications to reduce indoor formaldehyde emissions.
Substitute oriented strand board (OSB) for plywood. OSB uses small, fast growing trees, a more rapidly renewable resource than the more mature timber required for plywood, and generally uses an exterior-grade binder, reducing formaldehyde emissions.
Consider fiber-cement, straw-board, or other agricultural panel products to reduce wood use.
When using medium density fiberboard (MDF), specify products with an MDI binder, which contains no formaldehyde and emits no VOCs in use.
For furnishings, when MDF with an MDI binder is unavailable, choose the durability and aesthetic appeal of solid FSC certified wood. ‘Antiques’ is another term for reusable solid wood furnishings.

Summary: Wood Panels

Uses for wood panels include wall and roof sheathing, floor underlayments, ceilings, and interior walls. Wood is a renewable product, and requires less energy than most materials to process into finished products. However, the logging, manufacture, transport, and disposal of wood products have substantial environmental impacts. Standard logging practices cause erosion and consequent sediment fouling of streams and waterways, damage sensitive ecosystems, reduce biodiversity, and lead to loss of carbon stored in soil. The key to reducing these impacts is the minimization of wood use through material substitution, selection of wood from responsibly managed forests, and design and construction practices that control waste and minimize redundant components.

Forest Stewardship Council (FSC) certification is a widely recognized and respected standard for responsible forest management. FSC labeled products are certified as produced from responsibly managed forests, and plywood and siding are among the growing range of FSC certified products carried by two or more suppliers in the Monterey Bay region. FSC certification is desirable, but minimizing overall wood use is also critical to sustainable design. See Construction Waste Minimization for more details.

The invention of plywood helped reduce the amount of solid lumber and labor required for wood frame construction. Subsequent development and popularity of oriented strand board (OSB), manufactured from small fast growing trees such as aspen and poplar, has further reduced wood use per square foot of standard construction. Plywood consists of multiple veneers bound with a resin, usually urea formaldehyde (UF) for interior grade, and the more water resistant phenol formaldehyde (PF) for exterior grade products. Urea formaldehyde is less chemically stable than PF, and therefore emits far more toxic and suspected carcinogenic formaldehyde to indoor air. The relatively high formaldehyde emissions from urea binders make materials with phenol binders (such as ‘exterior grade’ plywood) preferable for indoor applications. OSB is generally bound with phenol resins. Medium density fiberboard (MDF), made from sawdust and adhesives, is common in furnishings, doors and interior partitions. MDF typically uses urea formaldehyde resins, resulting in long-term indoor formaldehyde emissions. A preferable alternative is the specification of MDF with MDI binders; MDI is highly toxic to manufacture, but does not emit formaldehyde or other VOCs in use.

For interior walls and partitions, there are a number of alternatives to plywood, OSB and MDF. Examples include boards made from waste wheat or rice straw, which are aesthetically pleasing, often stronger than MDF, and just as workable. Under heat and pressure, microscopic ‘hooks’ on the straws link together, reducing or eliminating the need for binders. (Generally small amounts of MDI binders are used.) Homasote, made of 100% recycled newspaper fiber, has actually been around longer than plywood and OSB, and its potential applications include structural roof decking, paintable interior panels, and concrete forms. Structural-grade fiber cement siding can combine sheathing and cladding in a single component, providing shear strength, protection from the elements, and reduced labor cost.

For More Information:

Bay Area Build It Green Materials Database

ACWMA Green Building Materials Resource Guide

While not universally available, FSC certified wood is becoming easier to locate and specify, and is offered by multiple suppliers in the Monterey Bay region. Ask your favorite supplier, or check with local businesses as a starting point:

Hayward Lumber
Also a source of MDF with MDI binders. (831) 722-7137 or (831) 476-3800

AGRICULTURAL PANELS

At the time of writing, agricultural straw panels are difficult to find due to a combination of intense demand, lack of supply, and the time required to bring a manufacturing facility online. However, the market is hot. One manufacturer surveyed for this document indicated the entire capacity of their factory (currently under construction) had already been pre-purchased – 15 years out! The CIWMB recycled products guide and the other websites below are good starting places.

CIWMB Recycled Construction Products Guide

GreenSpec
A fee-based service searchable by the standard UniFormat.

Oikos
A free website with information about a wide range of greener construction products

Center for Resourceful Building Technology

Resource Conservation Alliance
A forest conservation information clearinghouse

Program Contact

Ecology Action

Phone: 831.426.5925
Fax: 831.425.1404
Email