2

I have pre made truss ceiling joist in the garage. The joists are 2x4x21'.

I want to use space above the joists for storage. I want to sister a 2x6x21' or 2x8x21' next to 2x4x21' is this ok?

If it is ok how do I do this: nails, bolts? Any other recommendations? Or should I put the new lumber in between existing joists?

  • welcome to the site. Please take the time to properly format your questions. It makes them easier to read which will lead to more people reading them, which leads to better answers. I have edited the question to improve formatting as an example. – JPhi1618 Apr 22 '16 at 21:12
2

First you need to determine the weight of the items you plan to store. If the trusses were designed under the IBC/IRC or the UBC (and maybe the BOCA and SBCCI) codes, then they should of been designed with a 10 psf live load on the bottom chord. If you keep below this loading you should be okay, but you might want to check out the code requirements for your building. 1/2" plywood will add a 1.5 psf load. A 2x10 at 24" o.c. will add 2 psf (but a 2x4 will add .75 psf) to the ceiling. A 2x12 at 24" o.c. will add 2.5 psf. Subtract the plywood and add-on from the 10 psf to get what load you can add. The safe bet is to consult with a structural engineer familiar with your truss assembly. Could prove to be the lesser alternative to a truss collapse.

0

It sounds like you need to support the 2x6 or 2x8 from below with a load bearing wall or beam. If you will be walking around up there, then you should build it like floor not a shelf. Nailing floor joists to the ceiling trusses would probably be slightly less optimal than not nailing them together because flexibility of the joist is part of the strength, but I doubt it would make a huge difference. If you decide to sister 2x8 floor joists to 2x4 trusses, nails would be best.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.