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I'm trying to install an electric hoist (70 pounds) to the wood beam at the ceiling I'd like to know how much weight this structure can stand.

I attach an image to give a better idea of my project.

Wooden beam across ceiling

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    70 lb hoist unlikely to be a problem. Lift things with it, problems more likely. Beam is already holding up your roof, so it's not so much a matter of what it can carry as, what can it carry in addition to what it's already carrying. Which gets into the unpopular but true "hire an engineer," or else get the dimensions and materials of the beam and try to be your own engineer and hope you don't make mistakes with your house.
    – Ecnerwal
    Oct 24 '21 at 0:33
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    Are you sure it's a real load bearing beam and not just for show?
    – JACK
    Oct 24 '21 at 0:40
  • It would be an expensive showpiece from what I can deduce from this picture. And I'm familiar with a bunch of houses built with that type of beam as structure. Of course, if it's for show, then it is unlikely to hold up much, as it would not be properly supported.
    – Ecnerwal
    Oct 24 '21 at 1:02
  • Expose and see how the beam is supported. How far the hoist will be away from the wall?
    – r13
    Oct 24 '21 at 16:03
  • What is the span (length of beam) and how far over to the wall on each side of the beam? What is the size of the beam ?
    – Lee Sam
    Oct 24 '21 at 16:52
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You didn’t answer if the beam is 4x15 or 6x15.

A 4x15 that is 33’ long will support about 4,500 lbs. placed near the midpoint of the beam. A 6x15 that is 33’ long will support about 6,000 lbs. placed near the midpoint of the beam.

If the beam already supports the roof, then (depending on snow loads, type of roofing, etc.) and depending on how far it is to the next wall (I’m guessing about 12’ on each side of the beam) then the beam is already supporting about 30 lbs. per square foot (live load and dead load) times 12’ (6’ on each side) = 360 lbs. per linear foot along the beam. If the beam is 33’ long , then 360plf x 33’ = 11,880 lbs. it is already supporting.

This shows the beam is over stressed or just decorative.

Edit: If the beam is 6x15 and no snow, then the existing total load on the beam is about 10psf x 12’ x 33’ = 3960 lbs. If the maximum allowable is about 6,000 lbs., then there is about 2,000 lbs. the beam could support. (Verify that my guess of about 12’ from each side of the beam to the adjacent wall on each side of the beam.)

So, if my assumptions about the distance to the adjacent wall is correct, then you could add a small load (hoist) to the beam.

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  • It's 6x15, no snow at all,
    – Truxter0
    Oct 24 '21 at 22:16
  • so hoist will lift a persons body up to 360 punds.
    – Truxter0
    Oct 24 '21 at 23:31
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    Hoisting humans changes the story: prudence dictates that you add a wide margin of safety to every part of the chain. You should understand the difference between a dynamic and static load. Oct 25 '21 at 0:12
  • Yeah... humans move. Movement adds stress and load. Make sure everything in the equation is over-spec'd for safety. Maybe test it out with 400 lbs of wood or bricks, swing it around, bounce it, whatever you expect might happen, just to be sure your lifting mechanism itself won't fail. You wouldn't want 10+ feet of chain breaking and landing on someone.
    – FreeMan
    Oct 25 '21 at 14:46
  • thanx for all your comments, i'm still confused about if it's safe to attach the hoist to the beam. (def i will be doing some testing before using it)
    – Truxter0
    Oct 25 '21 at 16:27

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