Travelling to construction sites in the US and in Canada, I’ve noticed each country has a preferred wood-joist-to-steel connection method. These two methods are called slope cut and top mount.
Wood to steel used more often
In both Countries, I see steel being used more and more often in residential projects. House sizes have been increasing, and so have loads. Open design is also getting increasingly popular, which make for longer spans. Integrating steel beams in certain situations has the advantage of being able to bear much more load, on a compact form factor. Here is a description of how to properly connect the open joist TRIFORCE® to a steel beam using either method.
Slope cut
In Canada, slope cut is mostly used. This is when the bottom chord of the joist is set on a sill plate bolted to the bottom flange of the steel beam. The sill plate could also be bolted to the center of the beam. The OSB panel end of the open joist TRIFORCE® has to be cut at an angle so the top chord is flush with a sill plate bolted to the top flange of the steel beam as seen below in the illustration.
Bracing needs to be added to stop any possible rotation or twisting. Slope cut also requires exact measurements for the joist and beam to match up. In Québec, all plans have to be reviewed by a structural engineer before construction begins so this level of detail isn’t an issue.
Top mount with hangars
In the USA, top mount is preferred, unless otherwise specified. With this method, a difference of depth between the steel beam and the joists isn’t really an issue. Because there isn’t always a structural engineer involved in the project, top mount works out to be the best way to avoid problems.
Top mount doesn’t require lateral bracing either. The hanger is affixed to a sill plate bolted to the top of the steel beam, as seen above. You’ll be using a bit more material, though: you have to add wood filler for the connection to work properly. It also should be bolted to the beam.
Slope cut and top mount
Each method does the job. In the USA though, top mount is much more widespread. Unless you have a good reason to choose slope cut, such as design or aesthetics, you’re better off applying a method framing crews will be more familiar with.
Let me know if you have any questions or comments.
