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I would like to mount a hammock chair like the one below to the roof of my balcony. Or rather put a rope around a wooden bar (see the next photo) just like I were mounting it on a tree branch. However, I am not sure the wooden bar and its mounting points can stand the weight of me in the hammock (around 80kg). I've tried to do some pull ups and the bar seems stable enough, but I'm not sure if it would stand longer stresses and movements of the hammount chair.

What could I do to make sure?

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Mounting of ceiling member to a root rafter:

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  • We’ll need some info in order to help. 1) What size is the ceiling member? 2) How far does it span? 3) What spacing are the members? – Lee Sam Apr 11 '20 at 14:17
  • How is the cross member attached at the end to the roof rafters? Screws? Nails? How many? – Ack Apr 11 '20 at 16:52
  • Also, how is the roof section attached to the structure? Is this your house or a rental? What vertical supports are there on the outside end? It looks like that "roof" may be a 4-6ft corrugated plastic awning over a balcony door, supported by 1x4's or 1x6's. The cross brace highlighted closest to the building may be doubled, but I wouldn't trust the 1xX "rafters" or their attachment to the building (possibly nailed on) without more detail. – Eric Simpson Apr 13 '20 at 11:07
  • Keep in mind, although you may weigh 80kg standing still, when you start swinging, that load can easily double. Also, if someone like a guest haphazardly flops down in the chair the load could be much higher. (Last year I had 2 guests, pushing 120-130kg each, plop onto my porch swing at the same time. They broke three 1x2 slats, a 2x3 on edge brace, and cracked two 2x4 porch ceiling joists.) Consider others who might sit or swing in that chair. – Eric Simpson Apr 13 '20 at 11:21
  • @Ack: There are 5 horizontal ceiling members, each of ~ 5x20x400cm (2x8x157 inches), with spacing of around 40cm (~16 inches). They are attached to roof rafters with 4 nails at each end. I'm attaching a photo.> – dzieciou Apr 14 '20 at 16:59
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The horizontal board (rafter tie) and roof boards (rafters) are sized large enough for your purpose. The connection between the two is also adequate.

I don't think it necessary but if you were to want to increase the strength then I would start by adding (2) #8 x 3" screws to the connection from the rafter tie to the roof rafter. For more, I would suggest sharing the load with more rafter ties by placing a 2x4 or 4x4 over the top of (2) rafter ties (if you want to hang the chair between rafter ties) or over (3) rafter ties (to hang directly from a rafter tie as you plan). This can be attached with #8 screws (they are not structural, they just keep the board from moving)

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I’m from the U.S., and I know nothing about metric. But a 2x8 spanning about 13’ can support a total load of about 1,000 lbs., depending on the species and grade of lumber. (I used SPF.)

That means each end needs to resist about 500 lbs. each.

A typical nail used for framing here, would be a 16d nail and they are rated at about 110 lbs. each in framing. So, you’d need ABOUT 5 at each end where they fasten into the existing rafters, if you’re going to support the maximum 1,000 lbs. If not, you could reduce the number of nails. In your case, you’re supporting about 180 lbs. so you’ll need 2 at each end.

The roof rafters seem fine for such an additional load, especially based on the type of roof covering. (I’m guessing you don’t get 2’ of snow on the roof.)

(Sorry for this not being in metric. We make the rest of the world convert to our system.)

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  • Thank you. Non-metric system is not a problem to me. I am aware asking a question at English-speaking forum will require converting some numbers :-) – dzieciou Apr 18 '20 at 11:04

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