Hi

Bought an electric hoist from Lidl a couple of weeks ago to save my back when lifting the engine amongst other things.

Does anyone know how to calculate strength of joists? I intend to lay some of that slotted metal bar (framing channel?) over a number of joists to spread the load, and would like to know how many.

Joists are 35x70mm with about 5300mm span. Obviously also supporting the garage roof (double).

Motor is rated for 125kg, or 250kg if used as block and tackle, and book says mount for 500kg. Planned use is for bike engine so nowhere near those loads, but I'd like to understand what my rafters can and can't take.

If they won't take it safely, then what's the best way?

Thanks.

[Edited on 9/2/20 by gingerprince]

Rafters are made of what? Mounted to the wall how?

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Originally posted by coyoteboy
Rafters are made of what? Mounted to the wall how?

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What I did was to use a joist that is over the brick peers either side which gives the joist a 2 brick width support.
At this point I wanted to add a bit of adjustment so I used 2 short lengths of scaffold tube across 2 hoist, to give for & aft movement.
A third short length of scaffold above the two for & aft poles with scaffold pole clamps to secure them gave a very strong structure to hang the hoist from.
Longer scaffold poles would allow you to have multiple location points along the length of the garage and further spread the load across multiple joists.

I made a triangle in metal that went from both sides of the garage and joined in the middle of the joist,
no calculations, it was just there for piece of mind,

Sound like small joists to me span is large..if it’s part of a roof trusses they are normally only designed for roof loading...

Their are on line calculators...

Sounds about the same roof as my garage, not even close to being strong enough to hang an engine off. Personally I wouldn't even risk it, if it fails you trash the roof, damage the car & engine or yourself... Hire and engine lift or buy one from Gumtree, most folk want rid of them as they take up space. If you need to have the winch suspend it from a steel section properly mounted on top of the garage walls.

They should be designed for allowance of storage, maintenance access and for snow loading. Add a timber that spreads the load over several trusses and lifting a couple of hundred kilos for a short period of time shouldnt be an issue. (IMO)

[Edited on 10-2-20 by loggyboy]

I used to put two props from the floor to a joist with a car in between the props after lifting the engine /gearbox out I pushed the car back so I could put the engine on a trolly
You could bolt a steel angle to your joist to fasten the winch too first
Jacko

Having recently gone through building control, I was made to double-joist every other joist on a 4.1m span between 300mm tall metal I-beams using 8"x2" C24 grade beams. And that was just for a loft area.

Whilst I understand that it's probably overkill (and the inspectors probably just want to cover themselves), I would suggest the size of beams you've got aren't up the job.

If you're looking for long-term and feel inclined, I would consider inserting a pad stone on the side walls (assuming brick walls) and spanning an I-beam between which would allow for significant loads to be lifted if needed, otherwise have a look at gantry frames for use with block and tackle such as THIS, or if you're really not fussed, then a basic engine crane will do a pretty good job.

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Originally posted by Charlie_Zetec


Whilst I understand that it's probably overkill (and the inspectors probably just want to cover themselves),

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I made a timber A frame to lift my engine using some chain blocks.

Did the job but I had to lift the engine then move the car.

That's too small for my liking, I'd just weld up a separate frame or plough in some posts internally. Cheaper than rebuilding the roof and car below it.

Thanks for views all. Some varying opinions but enough in the negatory to tell me that it needs more thinking about and not just stick it up there (yub yub!). Certainly don't want the roof coming down on me! It is an attached double garage, but given the size of the joists it seems it's specced for light use. Plus, there is already some boarding up there for storage.

The hoist was more of an impulse buy (we've all done it at Middle of Lidl!), not likely to lift lots, just bike engine in the first instance. Think I'll return the hoist and go with plan A of just carry it, but get some help (have done it myself in the past but back trouble means I should really get assistance).

I have fitted one no problem lifting 250kg just spread the load over 5 beams.


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[Edited on 12/2/20 by ragindave]