I’m happy to report that last week’s blog about using open joist TRIFORCE® as Stair Girders generated a lot of interest. One question that came up and that we thought we should address was about possible rotation of the joist due to the lateral load created by the staircase. Is this possible? The simple answer is “no”.
We want to set the record straight right here in the blog.
Handling Lateral load without rotation
Rotation simply won’t happen because we look at every individual load case. What we recommend is based on the characteristics of the specific lateral load involved, not some generalized notion of load. With every side load, the correct filler, and full depth reinforcement, sometimes to both sides, prevents any rotating or twisting. In more demanding situations, a doubling up of the joists and the use of transfer clips can deal with the prescribed load.
We also recommend coil strapping if the header is shorter than the joist depth. You can use face mount hangers with the filler. Otherwise, I usually specify top mount hangers so if the filler is not installed, it is not an issue.
With these reinforcements, you are, in effect, creating a mini-beam at that location.
TRIFORCE® joists have proven effective as Stair Girders
In the 25 years that we’ve been specifying open joist TRIFORCE® Stair Girders, we have not had a call where the nails have just popped out due to stress. Granted, TRIFORCE® won’t be appropriate in every single situation. If the load is too great, we simply go to LVL Beams. However, in most residential situations, an open joist TRIFORCE® Stair Girder will work. This can save the home owner sometimes hundreds of dollars.
We are delighted that our readers are catching on about the considerable advantages of using the TRIFORCE® product and the benefits of its open configuration. When you purchase, design with, and install TRIFORCE®, we’ll provide the calculations for the support as per the specific situation.
We think that adds a lot of value to the product.