Clear Span, Girder or I-Joist
Clear Span, Girder or I-Joist
(OP)
Hi All,
I'm designing/building a two story garage and trying to determine the best method to support the second floor with a clear span. I searched the threads and didn't find quite the help I was looking for.
The idea is a 30 wide by 26 deep two car garge. The garage area will be 26x26 with the remaining 4' used by the stairs going up to a multi purpose room.
I want to avoid columns in the 26x26 area so I reviewed the span data supplied by a couple manufacturers for their I-Joist products. They both appear to be able to make the 26' span with an 18" or 20" deep joist. I'm concerned about flex though and wondered if supporting smaller I-Joists with two LVL girders would provide a less bouncy floor. I'm designing with 40 psf LL and 10 psf DL.
Any thoughts or suggestions?
I'm designing/building a two story garage and trying to determine the best method to support the second floor with a clear span. I searched the threads and didn't find quite the help I was looking for.
The idea is a 30 wide by 26 deep two car garge. The garage area will be 26x26 with the remaining 4' used by the stairs going up to a multi purpose room.
I want to avoid columns in the 26x26 area so I reviewed the span data supplied by a couple manufacturers for their I-Joist products. They both appear to be able to make the 26' span with an 18" or 20" deep joist. I'm concerned about flex though and wondered if supporting smaller I-Joists with two LVL girders would provide a less bouncy floor. I'm designing with 40 psf LL and 10 psf DL.
Any thoughts or suggestions?





RE: Clear Span, Girder or I-Joist
Bounce in joists - depends on their stiffness and the type of wood. Your live load deflection should be kept to the traditional L/360 limit, though to be sure, perhaps consider L/420. These are still in the 3/4" deflection range and with a clear span and no partitions above, you may get vibration regarless.
A supporting LVL may not do much, or perhaps make worse, the potential for vibration.
If this is for storage - don't use 40 psf for LL - you would need 125 psf.
RE: Clear Span, Girder or I-Joist
Breaking the span of the joists with a girder is not a good solution, and very ineffficient structurally.
RE: Clear Span, Girder or I-Joist