Design & Construction Guidance
Design for longevity
Prolonging carbon storage in wood products is essential for mitigating climate change. Ensure that buildings constructed with wood products are designed for extended (100+ year) lifespans in order to prolong the storage of carbon in the wood products.
Plan for reuse
Wood will release the carbon it has stored at the end of its useful life through decomposition or incineration. Make a plan for reusing the project’s wood products at the end of the building’s life. If appropriate, consider ancient wood joinery techniques or mechanical fastening to avoid adhesives that would prevent reuse.
Design for durability
Ensure that the wood products used in the building are protected from heat, water, and insects and will last the lifespan of that building.
Understand the right structural wood product for your building’s needs
Even though engineered wood products typically have a higher carbon impact per unit weight than dimensional lumber, they are stronger and therefore require fewer members, which may reduce emissions overall.By using whole building LCA tools (which use EPDs) it is possible to compare the carbon footprint of systems using engineered wood vs. dimensional lumber in order to select the system with the lowest overall embodied carbon footprint.
Look for low-carbon alternatives for the same application
Choose the lowest carbon wood product appropriate for each application. For example, oriented strand board (OSB) sheathing and plywood have comparable characteristics, but OSB has about double the carbon footprint of plywood sheathing2. Engineered wood products such as Laminated Veneer Lumber (LVL) and Parallel Strand Lumber (PSL) have a larger embodied carbon impact than sawn lumber, even accounting for their greater strength2.
Design for efficiency
Dimensional lumber and engineered wood products should be used efficiently to reduce waste material and the associated carbon emissions. For dimensional lumber, Advanced Framing (sometimes called Optimal Value Engineering) techniques can reduce the amount of wood needed in a building or application. For example, space studs at 24” on center instead of 16”, align studs with joists and rafters using a single top plate, align openings with stud spacing to eliminate or reduce header sizes at non-bearing walls, and eliminate unnecessary framing at wall intersections2. However, structural analysis should be completed to ensure that the resilience of the building is not impacted. Whole-building LCA tools should be used to assess actual carbon benefits of such techniques.
Use wood trusses and pre-manufactured wall assemblies, where appropriate
Wood trusses and pre-manufactured wall assemblies have been shown to use 26% less wood than traditional framing techniques, while also reducing weight and allowing for longer floor and roof spans7. However, if using engineered wood products, ensure that the additional embodied carbon from manufacturing still results in an overall embodied carbon reduction.
Ask for EPDs
Sawmills and wood product manufacturers keep a detailed inventory of material consumption and energy consumption. Ask for EPDs to promote more data and transparency in the industry.