Roof support?

[Number21]

I want to mount some sort of hoist on my ceiling to pull engines out of trucks. My shop is made from cinderblock, about 12' high, with a very shallow roof built from premade 2x4 engineered trusses. It's really hard for me to describe how it looks, but there's no lumber up there bigger than 2x4.

The trusses make a triangular shape with the roof and then have a "post" in the very center that comes down and rests on the joists. Would this be a good place to mount such a thing, in the center of the engineered trusses? Or maybe an engine is just too big to attach to my roof? Or maybe I need to reinforce the attic first?

I'll try to take a pic of the attic tomarrow. I already have a 30A twistlock outlet in my ceiling with a breaker marked "hoist", but I have no idea what was there or how it was attached...

 

[CraigFL]

Technically, roof loads are carried through the truss structure downward, so pulling from the peak of the truss would be more normal. If the weight of the hoist and engine is significant, you may want to spread the load out between at least two trusses.

 

[6768rogues]

I don't know where you are located, but here in moderate snow country roof trusses are made for a 35 lb./sq. ft. live load on the roof side. You would be attaching a sizeable point load on a truss or two. I would not do it.

 

[t. jones]

You sure he didn't have a floor hoist with wire running overhead and plugging into ceiling? I have put several skyhooks in my garages, what kind of trucks Mack?
Thanx Trevor

 

[Milwen]

Although the center post of a truss as you described is a good place to add a concentrated load, I would definitely not do it without having the truss manufacturer check it first. With a shallow pitch most wood trusses are only designed to support 10 psf on the bottom chord which is essentially just the ceiling finishes. Something as heavy as an engine could possibly do serious damage.

It's a very easy thing for the manufacturer to check if you can talk to them, but the likelyhood of them saying it would be ok is very small.

 

[ddawg16]

I think I understand what you are trying to describe......

My old house had a detached garage that sounds kinda like what you have.....I needed to pull the engine on my jeep so I drilled a hole at the peak of the roof....ran a big I-bolt through the hole and attached it to a 2x6 about 8' long....this spread the load across several of the A-frames....no issues...

 

[Number21]

Finally got to take some pics:

Basically I'd like to mount it right about where that metal cable goes down. I could put a peice of lumber between a few of the trusses there in the center to spread the load. It must be built strong enough to hold a 200# man at a single point, I only want to lift maybe 800-1000# max. Think that would work? Or too dangerous?

I just have to figure out how to get up in there...the attic hatch is conveniently mounted where you CAN'T put a ladder...

(me with my head in the ceiling)

 

[JohnFreeman]

".I needed to pull the engine on my jeep so I drilled a hole at the peak of the roof.."

Would seem to be far easier to head to Rent - O - Matic with thirty bucks...

 

[t. jones]

do you own or rent?
if you modify or damage eng. components it could come back to bite you

Thanx Trevor

 

[onewaydave]

Could you build a steel frame;
posts up the walls out of the way,
then in the attic pattern the steel like the trusses, brace as needed.

I wouldn't trust a/some 2x4 truss(s) to support an engine.

 

[Sokoloff]

Obviously, this is all "at your own risk, not mine" because I'm not your structural engineer.

That aside, it looks like you could carry a beam safely on top of the cripple studs there. (Inside the "field goal post" shaped void closest to the three mending plates.) I'd run a beam across 4-5 of them, and then carry the load on the center of that beam. If you're using natural wood (as opposed to a glue lam beam), install it crown up so when it's loaded, it spreads the load more evenly. Even with this, you risk deflecting the ceiling enough to crack drywall, etc.

I have a trolley and crane hoist in my hangar (on a HUGE steel I beam) and it's great, but for your situation, if it's one time, just get a cherry picker. If you're going to be doing it over and over, have someone who knows structures over to inspect it in person amd advise you. That's short money/effort, compared to getting advice from well-meaning internet folk, who can only see the couple pics you sent us.