TimberStrand® LSL – Engineered Solutions for Multi-Family Projects

January 13, 2014 in Wood Products - #tech talk #trus joist

The improving economy has led to a rapid increase in housing demand. Both single-family and multi-family (apartments and condominiums) have seen a surge in construction. More and more of the multifamily construction projects are turning to wood frame construction rather than steel or concrete. TimberStrand® LSL products provide solutions for high structural demand areas such as the rim board, wall framing and sill plates of wood framed multi-family projects.

Rim board has two primary functions within a structure. It is used to transfer vertical loads from above as well as lateral (shear) loads to the structure below. In our most recent code report, ESR 1387, we have expanded our vertical and lateral load capacities for our entire TimberStrand® LSL and TJ® rim board line up, including rim board up to 24” in depth as well as publishing maximum concentrated load and axial stiffness in the cross-grain orientation values. You can read the blog “Rim Board Thickness: Which one should I use” for further information on selecting the appropriate size rim board based on the demands from the structure as well as downloading our Trus Joist rim board literature TJ-8000.

Walls framed with TimberStrand® LSL studs will not only be straighter than traditionally framed walls, they can also handle the demanding loads placed on them in multi-family structures. Since TimberStrand® LSL is an engineered wood product, they can handle more vertical load in wall framing applications than typical dimension lumber of equivalent size due to the higher design values. It is also available in long lengths (up to 48’), which makes it the perfect choice for balloon framed walls where longer length material is needed. In addition, the ability to manufacture TimberStrand®LSL in solid sections up to 3.5” thick reduces framing time for areas where multiple ply studs or columns are required by eliminating aggressive fastener requirements as well as having design benefits for being a solid piece. See TJ-9003 for more information on wall framing with TimberStrand® LSL.


And don’t overlook the great benefits of using TimberStrand® LSL as top and bottom plates for wall framing. As stated in our code report, ESR 1387, TimberStrand® LSL used as a wall plate (face/plank direction) has an allowable crushing strength (compression perpendicular to grain, Fcperp) of 670 psi for 1.3E 2×4 and 2×6 plates. This value increases to 750 psi for 1.5E 2×8 plates! This is an industry leading value which may allow for a greater on center stud spacing if wall plate crushing controls the design.


Since TimberStrand® LSL is manufactured at an approximate average moisture content (MC) of 6% (and equilibrates to approximately 10% MC in dry service applications) the shrinkage concerns addressed by the International Building Code in section 2304.3.3 are virtually eliminated when TimberStrand® LSL plates are used in dry service conditions. And with lengths up to 48’, the number of chord splices in the top plates can be reduced which can reduce installation and design time. Finally, StrandGuard® TimberStrand® LSL is treated with zinc borate for protection against insects and decay for above ground, dry interior applications (AWPA use category 2), such as sill plates on concrete foundation walls. See TJ-8100 for more information.

Using TimberStrand® LSL can solve many design issues in wood frame construction in both multi-family and single-family construction. Contact our technical support staff at 1-888-453-8358 or email us for more information on TimberStrand® LSL or any of our Trus Joist products.