eI am installing a deck railing that will be directly above 5 1/8" x 11" glue laminated deck beam along the front of the deck. Along the sides of the deck, it will be doubled up 2×10 joists.
I can't find any documentation about if an aluminum post can mount directly into the beam. Everything I can find is for an alignment that is offset from a smaller joist and uses blocking. Can I safely install these using 8" lag screws directly into the beam?
On the 2x10s, one side of the post would align with the joists, which I would like to use lag screws on, while the other side would need blocking. Is that appropriate?
This is for a residential structure, in Utah, USA if any of that makes a difference.
Best Answer
I’m not an expert and likewise did not find any direct documentation on the issue of attaching surface mount posts to a laminated beam but I did find the following information that might help you make a knowledgeable decision.
The following Fine Homebuilding video references surface mounted guard posts. The main issue appears to be that the post as desired will not have any blocking perpendicular to the Rim joist. It would also be difficult to mount a reinforcing plate underneath. https://youtu.be/lTRquLcL6Jo?t=540
About the beam itself – is it balanced or unbalanced and is the axis orientation vertical or horizontal? How the beam is constructed will impact how it reacts to shear forces. I found the following guide useful: https://law.resource.org/pub/us/code/bsc.ca.gov/sibr/org.apawood.X440.pdf
Also, how wide is the post mounting plate? You will need to make sure that the screws are a minimum distance away from the edges of the board. I found the following document helpful in looking at the calculations needed. https://www.engineeringexpress.com/wiki/lag-bolts-in-wood/
Finally, this document mentions the issues with drilling holes vertically through laminated beams and it's corresponding impact on the ability of the beam to carry a load. It may be something to review. https://www.anthonyforest.com/assets/pdf/apa/glulam/Tech_Note_Field_Notching.pdf
I have a feeling that it will all come down to whether not not the code inspector believes that the guard rail post will handle the required 200 pound static load without an issue. Without any direct documentation, I'd suggest that you verify this yourself using a test version before construction being sure to test all 4 conditions: Mid-span of the laminated beam, mid-span of the 2-bys and testing the corner connections in both directions.
Good luck and let us know how it goes.