I am planning to set up a sail shade and want to attach a mounting point to the chimney to get sufficient height. The sail will be triangular and about 22 sqm. The chimney was newly built a few years ago and looks to be in good condition. But there will be quite a bit of force on the attachment, which I guess will be a regular hook. My question is: Do I need to worry about it holding up, or could the chimney collapse when it's windy?
I asked the prospective supplier, and he said the attachment needs to withstand 400 kg. What do you think? Is that reasonable? Can my chimney handle it?
I asked the prospective supplier, and he said the attachment needs to withstand 400 kg. What do you think? Is that reasonable? Can my chimney handle it?
If you care about your chimney, you don't attach any TV antenna or satellite dish to it (there are even those that have blown down because of it...). If you attach a 22 sqm sail to the chimney, you are probably quite crazy
Best regards
Best regards
I agree with Racer! Avoid putting stress on your chimney if you want it to remain intact in the future. Even if it may seem stable, it's really just a stack of stone with some mortar. It probably won't collapse or topple over, but it can become leaky. The chimney sweep won't like that.....
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I believe the chimney will hold, but I think it's quite naive to think you can have a 22 sqm sail up when it's windy.
22 sqm, regardless of the attachment point you have, is an enormous force.
the force on 1 sqm at 20 m/s is 240 Newton
the force on 1 sqm at 30 m/s is 540 Newton
22 sqm, regardless of the attachment point you have, is an enormous force.
the force on 1 sqm at 20 m/s is 240 Newton
the force on 1 sqm at 30 m/s is 540 Newton
That matches pretty well with the "400 Kg" mentioned if you assume that all three horns are equally ballasted. It would take quite a lot to get 30 m/s across a sail placed over a porch unless the house is in an extremely exposed location. Nearby trees would likely topple over too...John J said:the force on a 1 sqm at 30 m/s 540 Newton
However, I still wouldn't attach the sail to the chimney unless I planned to take it down when it's windy. Chimneys are not built to withstand lateral forces.
Ok. Thanks for the answers. The chimney is out. The next step is to instead place a point on the roof. How about buying a cleat, mooring ring, or something similar and securing it with a long bolt that goes through the metal roof and through the roof truss? That should be sturdy enough, right? It feels a bit scary to make it watertight, but shouldn't you be able to use the farmer screw principle, i.e., place a rubber seal in the passage? What do you think?