Mass Timber and Engineered Wood Products

Engineered Wood Products (EWPs) are just ways of combining wood components into stronger and more uniform products. Being based in the Pacific Northwest makes this a very prevalent topic as our native Douglas Fir is a very suitable wood for EWPs. This is a primer on EWP and what it means for design and construction.

I feel it is important to note that EWPs are only as sustainable as you plan for. This means planned harvesting of the lumber, replanting, and local sourcing. Many projects source EWPs from Europe, but luckily for us there are a few companies local to the PNW such as Vaagen, Freres and DRJ that each have their own specialty.

EWPs can be split into a few different categories by the size of their wood base components, from long fibers to short fibers, and width and thickness. The size of fiber usually corresponds to the application of the EWP being a panel product like Oriented Strand Board (OSB) or a linear product like Parallel Strand Lumber (PSL). Linear products will be best suited for spanning, while panels are often used for vertical applications or to resist shear force.

  • Lumber

    • Lumber products have a wood base component of sawn lumber which consists of long fibers. The sawn lumber is then laminated together to form a larger and stronger composite.

      • Glue Laminated Timber (GLULAM)

      • Cross Laminated Timber (CLT)

      • Nail Laminated Timber (NLT)

      • Dowel Laminated Timber (DLT)

  • Veneer

    • Veneer products have long fibers often from 2-8 feet long, similar to lumber, but have much thinner sheets which means they are laminated with adhesives.

      • Laminated Veneer Lumber (LVL)

      • Parallel Strand Lumber (PSL)

      • Mass Plywood panels (MPP)

  • Strand

    • Strand products are shorter fibers that visually resemble shreds or chips usually less than 12” in length. These small strands are then laminated and pressed into a panel or linear composite.

      • Laminated Strand Lumber (LSL)

      • Oriented Strand Board (OSB)

  • Other

    • Not all EWPs are just single laminate composites, and there are many other ways of increasing the size and strength of raw timber.

      • I -Joists

      • Finger Jointed Lumber

There are a few more things to take into account such as the lamination orientation being consistent, crossed or random, and the timber layup of your EWP.