ROOF TRUSS STRENGTH?

[UNSTUCK]

My garage has a very high ceiling, so I was thinking it would be nice to build a hoist that attaches to the roof trusses, comes through the ceiling and then uses like a HF hoist system. I'd like to be able to lift 400-500 pounds. In reality it would be less. Jeep tubs, roll cages ect.
I was thinking if I used 4x4's across my trusses to spred the load it would help alot. I just don't know how much load they can take. I've seen garages where people hang a lot of stuff from them, so they must be pretty strong. I just don't want my roof coming down.
Any ideas?

 

[solidfrontaxle]

It totally depends on the truss and the roof design and load. They aren't designed for much ceiling load (maybe 20 to 50 pounds per foot across the bottom, but if you do like you are saying, you should be fine as long as you keep the 4x4 as close to a joint as possible and make it as long as possible. Would probably help to scab a 2x4 onto the bottom of each truss to double up the load bearing surface. Also, check to make sure that the trusses bear on the garage wall on both ends of the truss instead of hanging off another truss in the house. Usually they do sit on a wall since gagrage walls are load bearing.

I used to be a truss designer but don't blame me if the house falls in. Truss designers aren't certified or anything...

 

[Brian P]

In the past, I have run a bar across 4-6 of the roof truss to distribute the weight, I dont think I ever lifted anything more than a SBC, It creaked and groaned, But I still have a roof
Now I have an I-beam with a chain hoist.

 

[UNSTUCK]

Thanks for the input. Any other thoughts?

 

[ichi-san]

They aren't designed for much...

x2

If you decide to do it, don't use hoist when you have snow on the roof

 

[UNSTUCK]

I just picked up 5 4x4's and 5 2x4's. All 8 ft long.
I'm thinking that if I lay 3 of the 4x4's perpedicular to the trusses they will span 6 of them. I will then lay the other 2 boards across the three and attach my hoist to them. I will then attach the 2x4's vertically from the 4x4'x to the top of the trusses.

Anybody see a problem with this? Is there a better way of doing this?

 

[solidfrontaxle]

Thats a pretty good way of doing it. That would give you about three 30 pound point loads on each truss, which isn't that big of a load. If you can, butt the three 4x4s up against where some of the webs of the truss come down (next to one of the bottom of one side of the W shape that the web pattern makes), that way you can try to spread the load into the rest of the truss (a well designed truss will allow the stresses to "flow" and more evenly distribute the load within itself).

 

[UNSTUCK]

I'll get up there tomorrow and lay everything out and then take some pictures. Then I'll see what you all think.

Thanks for your help.

 

[lewis]

I laid a 4x4 across three trusses and have lifted way more then I probably should have. It held up to holding a dana 60 many times. Pretty sure I know better now though and won't be using it anymore.

 

[cruiseroutfit]

Did you draw a FBD Lewis

 

[UNSTUCK]

I laid a 4x4 across three trusses and have lifted way more then I probably should have. It held up to holding a dana 60 many times. Pretty sure I know better now though and won't be using it anymore.

I'm breathing a bit easier now. But can I blame you when my house falls over?

 

[lewis]

I'm breathing a bit easier now. But can I blame you when my house falls over?

I had done it because I had a professor that told me he had done the same thing and lifted bullet bikes with his for 20 years or so. I think you will be fine. The good thing is that you will be able to tell if its going to work or not since wood makes noise before failure.

 

[Robert T]

I hang a elk or two from my garage every year and have not had any problems, I use a 6 ft peice of square tubing up in the rafters to support the weight and a come along to winch it up, never even heard a creek out of them yet

 

[ricsrx]

I have the the 2x6x8' laid across my trusses and have been pulling motors with it, the sheet rock has cracked on the seams down the center of my celing, no other problems.

 

[benjy]

Would home owners insurance cover a claim if something did happen?

 

[1\4elliptic toy]

My old house in kamas I used a very similar system to what your explaining and I lifted the bed of my toyota up there many many times while I was doing my 4 link. I think you will be fine.

 

[pELYgroso]

Unstuck, I think the way you described it is perfect. That's pretty much exactly what popped into my head when you first posed the question.

 

[Corban_White]

I have a system like that and it holds the very heavy scout top up next to the ceiling all summer. I did use some pulleys to spread the weight out.