Reinforcing garage attic trusses for storage

[kowalski7]

I've been meaning to arrange my garage attic space for storage and came across this webpage.
https://www.doityourself.com/forum/...orcing-garage-attic-trusses-storage-area.html

My attic is current set up with only one horizontal 2x4 beam. I was thinking of adding one additional 2x4 beam to each side of that original beam. My goal is lay some plywood down and use the space for boxes and other junk. Are additional 2x4s needed for support? Or should I just lay plywood down and start moving boxes?

 

[Kaizen]

Those bottom chords job is to pull the building sidewalls in not to support anything. If you can get 2x6 or bigger sistered and supported on the side walls then you can. You’re basically building another floor. The ends need to transfer load to the ground.
Just slapping ply up there is a bad idea


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[GMCGarage]

Was the advice on the other site not the answer you were looking for??

 

[Homerr]

Modifying trusses is a universally BAD IDEA.

Everyone with this roof layout wants to add something up there, you're far from the first to want to go there. These attic areas just weren't structurally designed to take the load. If you want to store some extra mouldings, decorations, or other light items that can span across multiple bottom chords you'll be okay. But taking it beyond that is not recommended.

I doubt even getting an engineer would help in any significant way, they usually hate this sort of work. There is not going to be much depth available over the top plate for sistering on some additional reinforcement. Also, keep in mind that any headers, especially 8', 9', 16' garage door headers, will probably need replacing or reinforcing if the roof members bear on them and you are adding a lot of load.

If you're super serious about storage then get a truss company to give you a bid on real attic storage trusses and just replace the roof over the garage.

 

[Michigan Mike]

Hey guys look at the picture of his [trusses. That looks like stick built framing to me not really trusses. It looks like the bottom [chord ] ceiling joist is already a 2x6. I think he just needs to look at a span table and if 2x6 is not enough to carry the load he wants then he needs to double up the 2x6 with the appropriate 2x8 2x10 ?

 

[Jeepster04]

You can essentially make a truss with what you have there.

If you're just wanting to store typical light boxed things, I would beef up the connections in the vertical 2x4 at the ceiling joint and the rafter and call it good. That vertical 2x4 will pull down on the rafters thus putting the lower cord in tension...

 

[Lynden]

Modifying trusses is a universally BAD IDEA. If you want to store some extra mouldings, decorations, or other light items that can span across multiple bottom chords you'll be okay. But taking it beyond that is not recommended.

I agree. What I did in my garage was build cantilevered shelves on both of the gable ends. I used Everbilt heavy-duty shelf brackets from HD. The bottom shelves are cut-to-fit 3/4" ply, reinforced with a 2x2 along the front edge and supported on the back with a 2x2 ledger. I mounted the brackets upside down for the bottom shelves so that the shelves were at the same level as the bottom 2x4s of the adjacent trusses. You need to put a spot of weld on the ends of the diagonal on the back of each bracket because the bracket is not designed to be mounted upside down. My bottom shelves are 21 inches deep and 20 feet long on both sides of the garage. That's a lot of storage. I used smaller Everbilt brackets and 3/4" ply for the second and third shelves. The second and third shelves are 12 inches deep and shorter because of the roof slope, but they also provide a lot of storage.

https://www.homedepot.com/p/Everbilt-18-in-x-16-in-White-Heavy-Duty-Shelf-Bracket-14835/202824731

https://www.homedepot.com/p/Everbilt-10-in-x-12-in-White-Shelf-Bracket-15254/202034279

 

[Kaizen]

Hey guys look at the picture of his [trusses. That looks like stick built framing to me not really trusses. It looks like the bottom [chord ] ceiling joist is already a 2x6. I think he just needs to look at a span table and if 2x6 is not enough to carry the load he wants then he needs to double up the 2x6 with the appropriate 2x8 2x10 ?

Tough to see but zoom in can see truss plates.




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[kbs2244]

Maybe what is called a "King Post" truss.
Made with 2x6's
Used in timber framing since the middle ages.

They look to be on 24 inch centers.
If so, and the load is boxes light enough to lift over your head, then go for it.

 

[Homerr]

Hey guys look at the picture of his [trusses. That looks like stick built framing to me not really trusses. It looks like the bottom [chord ] ceiling joist is already a 2x6. I think he just needs to look at a span table and if 2x6 is not enough to carry the load he wants then he needs to double up the 2x6 with the appropriate 2x8 2x10 ?

For a typical garage width of 20' adding in DF#2 joists @ 24" o.c. with only the middle 10' loaded will carry 20 psf. But 1) you can't physically get them in there, 2) the ends would have to be cut back so severely to match the roof pitch that they would fail in shear and only be worth about a 2x6 joist.

Even (3)2x6 at 12" o.c. as a retrofit isn't cutting it for this modest loading.

 

[kowalski7]

Alright then, looks like I'm going to add some larger gusset plates and some thin plywood. Wish me luck, hoping to store 4-5, 30-40lb bins up there.