Best Choice for Loft Floor Joists

[bad_idea]

I am building a 15x20 room in the corner of my 30x40 garage with a storage loft above. I would like to be able to store car parts and such up there. Question one - what load capacity should I shoot for? Second - which will be the best choice for joist material - solid wood, I-joists, or truss joists? I am considering both cost and performance. Where do you purchase I-joists or truss joists? Thanks all.

 

[jrsavoie]

I would look for steel truss joists

 

[CraigStu]

I can't give you exact figures as to what it was designed to handle but we did this once where I worked for the exact same reason- store car parts. The builder did simple 2x12 joists but on 12 inch centers vs more common 16. The joists spanned the 15 ft distance instead of the 20.

 

[billconner]

If the loft is full height all over, I'd say 40 psf live load. If it's only attic and not walking height, I might go to 20 psf.

I was going to look this up but building code site is off line for maintenance. I'd probably use sawn lumber the 15' dimension. (Might look at an LVL the 15' and then joists for 10' spans. ) Sawn lumber least expensive by far.

 

[K'ledgeBldr]

Best choice would be totally dependent on what kind of load- “car parts” is rather generic!

Right now, about the only thing that is “readily available” is dimensional lumber. I-joist, truss joist, and any other manufactured floor system manufacturer is backlogged, and/or making their big accounts their top priority.

Most of the big suppliers like Builder’s 1st Source or the like carry manufactured joists. There are also companies that specialize in just truss supply- they are the ones that usually have engineers in-house.