3rd bay ceiling joist for storage 2x4s

[ZionXIX]

Hello all.

I have a 3 car garage with a sizeable attic space that I would like to insulate and add decking for storage. The 2 bay side ceiling is composed of 2x10s at 16in oc. With a span of 22ft. The 3rd bay is 2x4s at 16in oc and about 8ft span. I would like to bring the deck level up to closer match the 2x10s height. The only options I can think of would be to criss cross with another layer of 2x4s or 2x6s to distribute any loads better but I'm still ultimately relying on those base 2x4s. I can't replace them with tearing down drywall. Can I double stack boards on end in line with the 2x4s and extra hangers? I've never heard of this being done. Also the exterior side of the 2x4s are resting on the top plate. I think that side would require additional hardware to secure.

*spoiler* I've already been walking on those 2x4s and I'm like 340 lbs.

 

[tncatadjuster]

The short answer is no.

 

[Kaizen]

Are these trusses with webbing on the 2x10 side? If they are they are most likely ok to support a floor as those would be attic trusses and designed for a floor. My 30 foot span truss manufacturer would have used 2x6 for the bottom cord if i remember correctly for an attic truss. You sure they are 2x10s? Pretty substantial for what you are describing.
Definitly no on the 2x4 side unless you can get bigger 2xs and sister them to the exisitng AND sitting on bearing points at both ends. Huge pain in the **** even if there was no ceiling.

 

[ZionXIX]

You are right. The larger side is 2x12s. My other thought is to literally put something like 2x8s or 2x10s in between the 2x4s. And then put my 3/4 OSB on that. I'm just looking to have storage space. No one is living up there or anything like that.

 

[ZionXIX]

I actually managed to find a source that described exactly what I'm trying to accomplish.

https://www.jlconline.com/how-to/interiors/beefing-up-attic-joists-for-living-space_o

 

[firebirdparts]

You can put a 2 by 12 beside the current 2 by 4 without bothering the sheetrock, but of course it's overkill for 8 feet. The comment about sistering is incorrect. That does nothing in this case. There are obviously cheaper options, but it runs into more work if you span across with a 2 by 8, which is awesome (still doesn't need sistering), and then you need to block up more. Putting a 2x8 directly on top of the 2x4 kind of solves both problems, but you need to figure out how you can keep it there. That step may not be worth the extra work if you can't get out to the wall end and nail it really solid to something that's both already there and accessible.

2 by 12's with a 22 foot span is really pretty strong. You're in a pretty good place with that.