Ricky McLain, Mass Timber Advisors: While cross-laminated timber (CLT) has the ability to span in both its major and minor axis directions (simultaneously), most of the time we don’t ask it to do that. We use it in one-way span conditions.

Glulam beams (or steel beams, or bearing walls, etc) frame perpendicular to panel span. There are exceptions of course for point supported systems. But as of now, those are the exception and not the norm.

However, even in a one-way CLT system, we often have isolated areas of two-way span conditions.

– At openings in the floor panels
– Floor penetrations for plumbing
– Box outs for small mechanical chases

Can CLT span two-way around a 3″ diameter hole without needing additional framing? Pretty much always, yes. What about around a 4 ft x 4 ft hole? Well…probably should take a closer look at that one. Maybe it can, but it’ll depend on things like:

– Size of hole relative to size of panel
– Proximity of hole to edge of panel
– Proximity of hole to end of panel
– Load and deflection criteria

While working on a mass timber project recently, I came across this helpful guide from Nordic Structures, showing prescriptive options for allowable openings in their floor panels without the need for supplemental reinforcing (i.e. beams around the opening).

Click here to view the guide.

Click here to go to the original post on LinkedIn.