Thread: Trusses w/storage on the lower chord

This is the first time I've seen trusses that appear to be designed to allow storage. Any idea what kind of a psf load these are engineered for?

I told the buyer to ask the builer and/or the truss manufacturer. I'm curious how much these can be loaded up. Has anyone else run across them?

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If they need the storage space, just cut out the webs like this guy did.

rick

Rick--
I'm not meaning to be a smartass about it, but what was cut in your photo are some of the webs, not the chords.

I used to run into them alot but I guess the builders today would rather put a sticker up saying trusses are not designes for storage.

The 2x6 bottom cord should hold just as much if not more than conventional framing. There may even be a stamp somewhere on the truss as to its load capacity. I guess only engineering could tell you the true load.

Only the manufacturer can tell you what load (if any) they are designed for.

Kevin,

My Bad. Your are correct. I corrected my post.

rick

Originally Posted by Matt Fellman

Any idea what kind of a psf load these are engineered for?

Attic with storage is 20 psf versus 10 psf for attic with no storage.
- See Table R301.5 for the above, and then this note below the table:
- - b. Attics without storage are those where the maximum clear height between joist and rafter is less than 42 inches, or where there are not two or more adjacent trusses with the same web configuration capable of containing a rectangle 42 inches high by 2 feet wide, or greater, located within the plane of the truss. For attics without storage, this live load need not be assumed to act concurrently with any other live load requirements.

Most trusses will handle 10 PSF live load anywhere in the attic non-concurrent with other live loads - i.e. the load on the outside of the roof. Lately many have also been designing for an alternate load of 20 PSF in the rectangle mentioned in the previous post.

Truss manufacturers are hired by contractors who are hired by owners/developers. Bidding is competitive in the process. Unless the building designer specifically calls out a storage load in the attic then virtually no truss fabricator will design trusses for it or they would lose the job.

Also you have to understand this Prior to the addition of the 20 PSF storage provision in the code, the light storage load requirement was 125 PSF. So if your trusses were build before say 2000, they most likely did not have any storage load in the attic. Designing trusses for storage load would have doubled or tripled the design load on the trusses in most areas.