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I need some help. I am trying to figure out the best way to strengthen my garage ceiling to create storage space up above. The problem is the house was built in 1997 with a 2x4 W truss system. The span is 28'. I can see a break in the truss under one of the joint plates. Would sistering 2x4's in one 12' and two 8' sections all glued and screwed be enough to make it safe for storage? I am adding 3/4" plywood as the floor but also elevating the floor with 2x4 laid on their sides going perpendicular to the trusses. I am also adding an attic ladder for access.

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    Suppose the bottom cords of the trusses can be strengthened to support the load of stored items, will the walls support all the extra weight? This would be the weight of plywood decking, the extra 2x4s to elevate, plus the items stored? Someone qualified has to assure you of this. Are you going to gain enough storage volume to make this worth it? Is this a detached garage or integral to a house? Maybe a better solution would be a storage shed. – Jim Stewart Apr 21 '18 at 9:52
  • Thanks Jim. I am re thinking this as well. The 2 x 4 trusses are probably the very minimum to hold up the roof and ceiling. The yard is small so storage sheds could be problematic. Thank you for your feedback. – BrianAZ Apr 22 '18 at 0:43
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As a broad statement, this is a terrible idea. Why? Your truss system is designed specifically to hold up the roof and, to a lesser degree, tie your walls together.

2x4s spanning 28' with breaks are clearly not up to the task of holding up plywood and sleepers (parenthetically, not sure why sleepers seem like a good idea, but I digress), much less whatever stuff you (and future occupants) load up there. It simply isn't in the design.

What you'd need is something resembling a floor system... sturdy beams running across the 28' dimension with reasonably sturdy lumber running perpendicular to the trusses. (That beam at the front, by the way, is going to interfere with your garage door/opener.) Or some engineered joists running parallel to the trusses, which might or might not be able to simply bear on the top plate. On top of that, we need to ensure that the load on the joists/beams is being carried appropriately to the floor through posts, which then need to be carried adequately on a footing.

So, ask yourself: is all this worth the trouble? You'd lose either headroom in the garage or headroom in the "attic" because of a need for decently sturdy framing lumber. Cost of time and materials isn't trivial. You might need to revisit your garage door opener mechanism. Ensuring adequate bearing for joists or beams isn't going to be simple. You're probably digging new footings in your garage floor.

Storage sheds or offsite storage units start to look pretty good at this point.

So, capsule summary: this can be done. You need actual engineering expertise to do it appropriately. It'll cost a lot.

The alternative is to just chuck some plywood up there; undermine the structure of your garage; then call a contractor in 5 years to fix it all at great expense.

Disclaimer: I'm a professional carpenter, and I'd rather not have to charge people money to fix things like this.

  • Thank you for the feedback. I was going take the sleepers to the top of the walls strengthing the cord. The cord itself has a 2x4x20 and a 2x4x8 with a gusset plate at one of the v's. The problem is the trusses are probably the minimum in construction code which leaves little to add storage. When I bought the 3/4 ply wood and really to a look, I had to take pause. If the distance was shorter I would have just run 2x6's and not touched the trusses. Now I am facing something a little more expensive with either steel or as . I need to go back to the drawing board. Thank you for your expertise. – BrianAZ Apr 22 '18 at 1:03

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