Good day everyone . Wondering if anyone would know what size beam to use for my mezzanine/ living area in my garage. The span would be 20 feet long. The span would run parallel to the wall which is 15 feet away. Will be using joist hangers to attach joists to side of beam. Thanks for any help
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What size engineered beam
- Thread starter Bangon61
- Start date
ssdave
Banned
Using a total load of 70 pounds per square foot (40 live load, 30 structure load, 525 lb/ft of beam) I come up with a maximum moment in the beam of 26,250 lb-ft. That requires a 5 1/4" x 11 1/4" Truss-Joist Weyerhaeuser Parallam PSL 2.0 beam. That doesn't consider deflection; and it may have some "bounce" to it; that is the bare minimum beam that won't fail under a standard load.
The Truss-Joist design guide has a span/deflection table, and that table shows that for a L/360 deflection, that a 7" x 14" beam is required, for a maximum allowable load of 563 lb/ft.
So, I would specify a 7"x14" PSL 2.0 engineered parallam beam. That will adequately carry the load, will not excessively deflect, and should preclude most "bounce". Carefully coupling the wall on top of the beam to the beam or floor, and bridge blocking the floor joists should eliminate most bounce.
Here's the link to the TJ design brochure: http://www.wood.tcaup.umich.edu/lectures/TJ-9000.pdf
The Truss-Joist design guide has a span/deflection table, and that table shows that for a L/360 deflection, that a 7" x 14" beam is required, for a maximum allowable load of 563 lb/ft.
So, I would specify a 7"x14" PSL 2.0 engineered parallam beam. That will adequately carry the load, will not excessively deflect, and should preclude most "bounce". Carefully coupling the wall on top of the beam to the beam or floor, and bridge blocking the floor joists should eliminate most bounce.
Here's the link to the TJ design brochure: http://www.wood.tcaup.umich.edu/lectures/TJ-9000.pdf
Last edited:
ssdave
Banned
To be clear what I mean by "couple the wall to the floor". The framed wall should have the stud surface aligned with the beam face. Sheathe the wall with 1/2" nominal OSB, and shear nail all edges at 3" o.c. with 12 penny x 1 1/2" ring shank nails. Nail to each stud in the field at 5" o.c. spacing. The OSB needs to be horizontal in 8' sheets at the bottom of the wall, and lap down onto the parallam full width of the beam. Nail the OSB to both top and bottom of beam, 1 1/2" in from the edges, and nail to the bottom wall plate at the 3" spacing. Tight joint all splices on the middle of a stud.
A proper engineered detail of this shear wall construction might take you down a considerable amount in beam size, depending on the code and requirements where you live. Personally, I'd just go with the larger beam, and still shear wall the beam. Usually the cost of the over-design on the beam is cheaper than the engineering, and your engineer may be overly conservative and require both large beam and shear wall anyway.
A proper engineered detail of this shear wall construction might take you down a considerable amount in beam size, depending on the code and requirements where you live. Personally, I'd just go with the larger beam, and still shear wall the beam. Usually the cost of the over-design on the beam is cheaper than the engineering, and your engineer may be overly conservative and require both large beam and shear wall anyway.