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I assembled an hard-top gazebo which has steel loops at the inside peak. I wondered how best to hang a ceiling fan.

Inner steel roof ridge inside gazebo

The flat part is 3 1/8 inches:

Flat part of ridge showing 3 1/8 inches wide

The gazebo is designed with a roof above the interior ridge, something like this:

Diagram of the water shedding roof and the interior ridge

My first thought was to just using self drilling screws to mount a steel electrical box, but I didn't know if I should trust that method to fasten the box. There is no reasonable way to get access to the zone between the two ridges, so that rules-out a nut/bolt solution.

A similar solution would be to drill and tap some holes. That steel is 1.6mm thick. I suppose I could tap the holes, put in some bolts, and then additionally twist some wire around the box and loop, so if the bolts gave out, at least the fan wouldn't fall on someone's head!

Another thought was to cut the loop, leaving two "studs". If I then used a die to make threads, I could put a lock washer and nut on the studs. But that's going to be very tight quarters, trying to make threads on the improvised studs.

I'm afraid to remove any of the existing fasteners because there are a lot of forces in place, and the risk is simply too great to remove a bolt holding the structure, and then not be able to get it back in. I have experience with removing a bolt elsewhere in the structure, and it was very difficult to replace.

If I would have thought about this before assembling the structure, it would have been easy to bolt a steel box in place, but now that the structure is assembled, it would be way too much work to do a nut and bolt solution (I'd have to remove all of the roof panels on one side).

Any thoughts for how to best accomplish a safe but easy way to hanging a ceiling fan in this situation?

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  • Blind rivets only require access to one side. Be careful about selecting materials as you want to minimize corrosion.
    – HABO
    Jul 21 at 20:14
  • @isherwood yes, fabricating a custom bracket would be possible. I could get nuts on if situated in the places where roofing panels were corrugated upwards. Not that easy for me to fabricate the bracket, though.
    – Dale
    Jul 21 at 20:24
  • @HABO I hadn't thought of rivets. I have an aluminum pop rivet kit, but I'm not sure I'd trust completely them. Good point about corrosion.
    – Dale
    Jul 21 at 20:26
  • 2
    I would bet the designers of this gazebo intended those metal loops to be used to hang things. Jul 22 at 3:12
  • Does the mfgr of this gazebo offer a structural steel beam that attaches to the roof or to the two loops? They may have a system designed for hanging things, including ceiling fans. Jul 22 at 3:43
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I would drill suitable sized holes and fit 4 or even 6 rivnuts in M6 or M8 size.

Rivnuts are easily found and once the hole is drilled, you nut them up and they collapse on the far side like a rivet. They take a lot of force to pull out.

Rivnut picture with description

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Looks to me like that ridge channel has exposed flanges to which you could mount a bracket with bolts. Some aluminum bar stock would work well to create a mounting plane, then you could mount a plate or just the box. You'd mount your fan box to that. I'd use stainless bolts and nylock nuts.

     __________________________
    /__________________________\
   //        ----------        \\
            |          |

It's surprisingly easy to fabricate brackets like this. A little planning and a vice and you can bend 1/4" x 1" aluminum easily. You can then bolt anything you like to it.

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Hang a ridge pole (2x4 or 2x6, one piece, not finger jointed) inside the two downward projecting metal loops. Attach a fan box to that. There are fan boxes designed to fit the edge of 2x structural lumber. Paint the ridge pole to match the color of the metal roof. The extra spacing downward will help to provide the clearance of the blades from sloping roof, but be sure that there is no interference with purlins shown in the picture.

Such a ridge pole would allow easy hanging of other items.

If you want to seriously consider this, I would offer some suggestions on how to lock the ridge pole without drilling into the metal.

What brand and model of fan are you intending to install?

EDIT

IIRC some of the fans I've installed had two different lengths of hanging tubing in the kit, but both were for level 8' ceilings. On taller and sloping ceilings I have bought extra long tubing from a fan store.

EDIT'

A wooden beam outside can be attacked by carpenter bees or carpenter ants. Perhaps a structural steel beam would be better than a wooden 2x4. Something 1.5 inches wide would accept a fan box intended for the edge of 2x lumber. Maybe the heaviest gauge of steel stud or similar configuration.

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    I've seen installations with a steel pipe (~1" diameter) used in the manner you suggest, though you might have to search a bit for the proper mounting equipment. (If you do use a pipe though, recommend capping both ends, or you'll have bees/wasps/hornets/spiders etc. nesting inside.) Jul 22 at 17:51
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1.6mm steel is pretty thick, as sheet steel goes, and plenty strong enough,

I'd just use #6 self drilling steel screws to attach a surface mount fan box.
4 screws should be plenty, 8 would be massive overkill, But you're allowed to drill extra holes in electrical boxes to attach them to things.

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I see absolutely nothing wrong with your idea of self-drillers, assuming you have sufficient space behind & you can get maybe 4 screws of sufficient size through your mounting plate. You can also consider your plate self-drillable if the existing holes feel a bit small.

I spent 10 years as a maintenance engineer in retail - & self-drillers were the go-to for semi-permanent mounts to such as supermarket shelves when the provided mount points were insufficient to just bolt through, even in areas the public could get their clumsy fingers to try break things. [If something will survive the public in retail it will survive most things.]
Self-drillers come in sizes from 'will just about hold a matchbox' to 'can swing from it on a rope'.

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Here is the way I ended up doing the ceiling fan mounting in the gazebo.

The bottom line is that I went with pop-rivets, plus I used a bolt as a secondary safety measure.

First I cut a slot in the electrical box:

angle grinder cut of electrical box

Then I used 4, 3/16 pop rivets to mount the box:

steps to pop rivet box to ridge

Finally, I put a bolt through the box and the gazebo loop as a safety measure:

electrical box mounted with bolt as safety

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