Can my garage roof (truss system) hold a camper shell?

Hearsay...ya gotta wonder where people get their info sometimes and then why they repeat it.

Yes, you can hang things from engineered trusses. The answer is always, how much??

Do you have sheet rock on the ceiling now? To give you an idea of what a system can hold, typical ceiling rock is over 2 pounds a sq ft (2.2 more likely). Add mud, lights, door openers, and truss planking, and you're over 1000#'s for a small garage, just hanging on the bottom side. Most codes allow up to three layers of shingles (ugh...bad plan, but another day). Add 4#'s per sq ft, per layer for that. Three layers on that small garage with avg slope, would add another 6600#'s.

Dependent on where you are, you'll probably have snow loads as part of the equation too; 10, 20, or more pounds, per sq ft factored in.

Throw in a guy working up there for a spot load (working in the attic).

Can you hang a canopy? Two options for you here: hire a licensed engineer and have him run the numbers and give you a piece of paper saying yah or nay (I like engineers by the way; I am just fully incapable of performing that job) or throw a hat into the realm of common sense based on readily available data. Latter works pretty good for that minor stuff.

Full disclosure; I'm not an engineer (redundant statement now), but I've installed at least one truss, can read drawings, code, and building requirements, can add sometimes and have been in the industry for over 30 years. And I stayed in a Holiday Inn Express once.

Since we don't know the loads your trusses were designed for, or whether your trusses were designed for access and storage, I would guess that the more you can distribute the weight between the trusses, the better off you will be. The sandwiching that you propose seems adequate for a 200 lb load.

I use a Harken Hoister to lift my 8' long canopy off of my truck in my garage and have done so for 5 years without any issues. I also use two ratchet straps as a safety/back up.

My father-in-law worked home construction and repair type jobs all his life. He told me to never store anything, or hang anything from the trusses in a garage. They will hold ok, they can support the weight, but the roof will begin to sag over time.

For what you're proposing, if you don't want long term damage on your building, support the bottom of the trusses from the floor up, so the weight is on your (new) upright supports and not the roof itself. Then, you can hang a semi-truck from it without any affects to the structure.

You've got to remember, in homes with second floors, builders use floor joists (2x12's) or larger that can be walked on and are heavy enough to support a lot of weight. The trusses in your garage ar all 2x4, and they are no even a real 2x4 inches any more either!

Find a way to support from the floor, and you'd make my father-in-law very happy!

Your bottom part of the trusses were most likely only designed to hold sheet rock. That being said, many people do it. I will be when my garage is finished this summer.

It it were me, I'd have no problem doing what you propose. I have truss construction in my house and can walk in my attic with no problem. I don't think I'd support it by just one truss, but spreading the load like you propose should be ok.

Connect to the "panel points" on the trusses. They're the places where the bracing/bridging touches the bottom chord of the truss--where you see the punched metal "press plates"

I'd use a 2x6 against the sheetrock with a Tek screw into the bottom chord at the panel point of every truss it crosses.

A canopy shell weighs what, 200-300lbs at most? If you span 4 trusses on each side, you're looking at 50-75lbs per corner or 25-37lbs per truss. Go for it. I know of several people who hang their camper shells from the roof.