Maximum span for built up floor joist
user-89752
| Posted in Construction Techniques on
I’m building a 30 x 40 ft. garage with a 2nd story loft. I would like to make the 30 foot floor joist span without using a supporting beam on posts. Is this possible using the composite, built up floor joists?
What is the maximum span that these type of joists can make using a strategic nailing pattern to maximize stiffness, glue and tounge & groove subfloor?
Thanks
Replies
The rule of thumb I use is : 1/2 the span plus 1 equals minimum joist width.This,however is for conventional lumber and would yield for 30 ft, a 16" wide joist.For a built up I'd start by checking "Pocket Ref" available at most good hardware stores, to check on span limitations.
Don't exactly know what you mean by "built up floor joist".
A 24" deep wood webbed floor truss will span that far. There will probably be some vibration, but it shouldn't be terrible.
Whatever you do, avoid listening to anyone who tells you that you can use 16" (Or 18") I-joists if you put them at 12" O.C. or some other B.S. like that. Read my thread on Floor Vibration for more info on the subject.
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Sonny,
I'll probably get hammered on this one from other people posting but here goes...
Georgia pacific makes a floor joist to span that distance, but expect some deflection without support. The depth of this joist is 16" with a 40 psf live load and 10 psf dead load. Spacing is 12" o.c., max span distance is 30'- 2" with a glued and nailed 3/4" subfloor. The joists are the WI 43 series with a flange width of 3 1/2 " and a web thickness of 3/8" (plywood web not o.s.b). Floor stiffness can be improved by gluing tounge and groove joints and using screws instead of nails.
Not meant to hammer jack but plan to use the taller open web truss. You'll never regret it.
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