Bottom Chord of Truss as Attic Storage
Bottom Chord of Truss as Attic Storage
(OP)
I would really appreciate some help with a structural question about my trusses in my home. I'm doing some demo to my house, older split-level type house, and want to open up part of the first floor by taking down a wall in the center. I really don't think it's a structural wall - there is no footer under it in the crawl space. Asked my dad's friend to help with some of the carpentry. He is an older handyman guy and thinks that taking the wall down will prevent me from using the bottom of the truss for storage space in the attic anymore, that we run the risk of falling through the ceiling if we try to take down the wall and continue to use the attic. I'm not sure I believe him. All we store up there is clothes and decorations and that kind of crap.
The outside dimension of the house is 27' and the truss spans that way. The trusses are 24" oc and all the members are 2x4. We've got 1/2" ply laid across the middle section so we can slide boxes and stuff in there. I think the roof slope is 5/12, because it's not even 5'3" to the top of the truss in there. You can't stand up. The center to center measure of the truss joint is a little less than 9' but I didn't want to move all my boxes and pull up the plywood to measure it exactly. It's pretty close to that though.
The downstairs wall is currently right in the middle of the house, so it's about 13' from either exterior wall. We want to demo the whole thing, including the two cased openings. We are building a new partial wall that will be a little further in to one side, so only about 11' 6 from the exterior - but it won't go the whole way.
I would really prefer not to have a beam and just have a nice flat ceiling in the open spaces. But this guy is making it sound like my house might come down. What do you think? Do I need to put in a beam on the portions I want open so I don't get sagging when I put stuff in my attic or when we crawl up there to get something? We're not heavy people and we're not storing free weights, just regular attic stuff.
Thanks for advice. I'll try to attach a sketch.
The outside dimension of the house is 27' and the truss spans that way. The trusses are 24" oc and all the members are 2x4. We've got 1/2" ply laid across the middle section so we can slide boxes and stuff in there. I think the roof slope is 5/12, because it's not even 5'3" to the top of the truss in there. You can't stand up. The center to center measure of the truss joint is a little less than 9' but I didn't want to move all my boxes and pull up the plywood to measure it exactly. It's pretty close to that though.
The downstairs wall is currently right in the middle of the house, so it's about 13' from either exterior wall. We want to demo the whole thing, including the two cased openings. We are building a new partial wall that will be a little further in to one side, so only about 11' 6 from the exterior - but it won't go the whole way.
I would really prefer not to have a beam and just have a nice flat ceiling in the open spaces. But this guy is making it sound like my house might come down. What do you think? Do I need to put in a beam on the portions I want open so I don't get sagging when I put stuff in my attic or when we crawl up there to get something? We're not heavy people and we're not storing free weights, just regular attic stuff.
Thanks for advice. I'll try to attach a sketch.





RE: Bottom Chord of Truss as Attic Storage
RE: Bottom Chord of Truss as Attic Storage
But since the bottom chord has been used for storage it is entirely possible (in fact rather likely) that the existing wall has become load-bearing even though it isn't much additional weight.
It is unlikely (but still possible) that continuing to use it as storage will cause collapse after removal of the wall(depending on the weight of the things in storage as bowling balls are obviously different from pillows) however it is highly probable that the deflection of the truss would become noticeable and I'd be worried about the plate connections being overstressed.
You should reinforce the joint connections with plywood and nails if you intend on doing this. These plywood gussets would improve both the deflection and the worry about the existing metal plates. But most people don't want to do that. And to determine the size of plywood and number of nails into each member you should hire a local structural engineer.
RE: Bottom Chord of Truss as Attic Storage
I'm fine with reinforcing the plates if you think that's a viable solution. Obviously, I'm not a structural engineer! but my basic understanding was that if it's not a load bearing wall, it can go away and the remaining load-carrying members should continue to function as designed. All these new open floor plan houses with the huge spans, but they probably aren't 2x4. So you think maybe the bottom chord was never designed for any load? That's disappointing.
RE: Bottom Chord of Truss as Attic Storage
Attic access is code mandated.
It is a viable solution however an engineer would need to take a look at the existing trusses and analyze the forces to give you a final answer. Everything that you want to do is possible, the only question is how much are you willing to spend to get there.
Most truss bottom chords are designed for some loading but rarely is it enough to be considered storage loading.
If the AHJ has copies of the drawings you may be able to see what kind of load (if any) was specified.
A lot of designers will design for 5psf on the bottom chord to account for the weight of the ceiling.
RE: Bottom Chord of Truss as Attic Storage
RE: Bottom Chord of Truss as Attic Storage
The attic access hatch is so you can get up there to do repairs or inspections. Not so you can store things up there.
The trusses were most likely not designed for storage loads. The non-bearing wall may help with that some. But it's adding load on your floor joists that they weren't designed to handle.
My suggestion would be to take out the wall if ya want. and quit storing stuff up there.
RE: Bottom Chord of Truss as Attic Storage
Local structural came out last Friday to take a peek. Bottom chord is actually 2x6, not 2x4... guess I didn't dig down in the insulation far enough. And apparently that really changes things. Anyway, he ran the numbers for us and said we're just fine for light storage up there.
Thanks for the advice, it was a good call to spend a little $ for peace of mind.
RE: Bottom Chord of Truss as Attic Storage