Holes in Parallam® PSL - How to get it right


When designing a home, identifying where to run plumbing and electrical can be a real challenge! Redesign? Reroute? Cut holes? If the surprise demand for a hole occurs during rough-in, you may have more options than you think. With Parallam® PSL, the addition of a hole is a straightforward and simple process.

Parallam® PSL is a strong and consistent engineered wood product (EWP) ideal for long spans and open floor plans without intermediate posts or columns. Parallam® PSL also has a warm and unique grain, perfect for applications with exposed beams. This strong and straight EWP arrives to job sites in solid sections for fast and easy installation.

The quickest way to determine what kind of holes can be added to a Parallam® PSL product is to look at Weyerhaeuser’s specifier’s guide for Trus Joist Beams, Headers, and Columns for your region. These documents can be found through Weyerhaeuser’s specification center. The sections on Allowable Holes in Weyerhaeuser’s specifier’s guides illustrate the size and location a round hole can be drilled for a uniformly loaded beam. In the case of a uniformly loaded beam that is 7 ¼” - 18” deep, the guide will direct the reader to where a round hole up to 2” can be placed.

Parallam Beam with Holes

In cases where a hole diameter up to 2” is not adequate, or the hole must be placed outside of the specifier's guide allowed hole zone, ForteWEB ™ will allow you to design a hole in Parallam® PSL as well as provide information about design values and capacities for both the member, and the hole. The allowable hole diameter depends on several factors such as member depth and width, loading, span and hole location. In the ForteWEB™ scenario below, two 12” holes centered along the depth where the first hole is 4 ft. and the second hole is 9 ft. from the left support were added to a 7” x 18” 2.0E Parallam® product spanning 15 ft. Here, a 12 PSF Dead + 40 PSF Live load is applied with a 15 ft. tributary width.

For questions about adding holes to Parallam® PSL members, consult Weyerhaeuser Technical Support. Adding holes to a Parallam® PSL beam or header can be done in a pinch without the headache. Checkout Weyerhaeuser’s specifier’s guides and ForteWEB to find a design that will work for your jobsite.