Our Tip: When ceilings are applied to an I-joist system they need to be strapped before drywall is installed

If you are constructing a cottage or home using an I-joist floor and beam system, the ceilings that are to be finished with drywall in the areas below must be strapped prior to the application of drywall. Why? The material the I-joists are constructed of is difficult to screw into the drywall directly. If the drywall is applied without the ceiling being strapped, the drywall screws may not pull the drywall tight enough which can cause the screws to snap off.

A little background: Up until the usage of I-joists became more common in the late 1990’s, dimensional lumber such as 2 x 10’s and 2 x 12’s were used when constructing floor and beam systems. However, these materials typically result in noisy and bouncy floors. Also, you can’t run pipes through them without reducing the integrity of the structure. (You have to provide additional support for large pipes.)

The wood I-joists or floor trusses provide strength and allow greater spans with fewer support posts and beams. And they also eliminate many of the issues created by using dimensional lumber for your floor systems, including making it much easier to run pipes and wiring since there is either web space in the truss system, or perforated “knock outs” in the I-joists to allow the passage of mechanical components.

If we had to rate floor joist and beam systems from good to best, dimensional lumber is good, floor trusses are better but more costly, and I-joists are best.

I-joists are usually full-length allowing for faster construction times and while there is a one to two percent cost increase over dimensional lumber, the reduction of problems can prove to be worth it.

Discover more design-build considerations with our last Better Way to Build Tip.

Photos: TrusJoist, A Weyerhaeuser Business, Limit States Design, October 2002 NW/5M, USA