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I want to hang n fan in a covered pavilion which has a gazebo like roof, held up by rafters. I've purchased a ceiling fan box/support that is designed to fit between joists, but there are no joists. I was wondering if I could use 2 stacked 2x4's attached perpendicular to the rafters (with lag bolts) and then connect the fan box between the two by fours.

This photo shows the roof rafters and the drawing indicates the idea. The other photos show a mock-up of what it would look like (ignore the clamp, it is just holding the mock-up together -- in the application the 2x4's would be attached to the rafter with bolts).

Basically, the 2x4's create a 'joist' for the fan box to attach to. (The plates on the end of the fan box are aligned so that they can only be attached on the ends, and not flat against the joists).

Will this work? Or is there another way to do it?

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brhans
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bill333
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  • Are you OK with having the fan a bit off-centered in the gazebo? – ThreePhaseEel Jun 23 '20 at 23:44
  • I'd prefer it be centered. The outlines I put on the photo aren't precise; I would center it if possible. Does it make it easier if I don't? (I do not want to do an angled install though, like the ones on a cathedral ceiling) – bill333 Jun 24 '20 at 01:01
  • It makes it *far* easier if you are willing to accept off-center, because then you can use a saddle box attached directly to a rafter – ThreePhaseEel Jun 24 '20 at 01:09
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    You could easily run a short piece of 2x4 level between two rafters at the peak, and use the saddle box on that. That's what I did for my cathedral ceiling porch, worked beautifully and should work here as well. – PhilippNagel Jun 24 '20 at 01:52
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    Your crossbar and box unit are not rated for exterior use. – Jimmy Fix-it Jun 24 '20 at 04:05
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    Dude, seriously, one of the best "first posts" I've seen! Well done! Clearly asked. Good details. Nice, focused photos. If we had a Hall of Fame for first posts, this would be a definite entry! – FreeMan Jun 24 '20 at 13:50
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    @ThreePhaseEel It's obviously a radially symmetric space. Off-center will look stupid. Laziness is the only reason to do it that way. Ask yourself what you would think if you paid a professional to do it and that's what they did - you'd fire them and never call them back, right? It's a very quick and very easy job, even with limited framing experience, to build out a simple support structure up there to hold the box in the center. – J... Jun 24 '20 at 14:08
  • @J... -- I wouldn't consider that sort of substructural mount to be automatically acceptable for fan mounting -- the 2x4 itself is going to be fine but I wouldn't trust random fasteners to hold it up acceptably given that fans are a rather dynamic load. (Perhaps a Strong-Tie LSSJ at each end would do the trick, with the slope being set relative to the rafter and the skew left at 0?) Anyway, I don't know if the OP had other plans relative to what they were doing here, either. – ThreePhaseEel Jun 25 '20 at 00:01
  • @ThreePhaseEel Of course a random mount with no design and "random" fasteners isn't automatically acceptable. All I said was that making an acceptable mount isn't difficult - there's no implication in that statement that "not difficult" = "impossible to get wrong". – J... Jun 25 '20 at 00:22

2 Answers2

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A lot of this comes down to aesthetics and practicality, so you will probably get lots of right answers. Here's my take:

I would run your short piece of 2x4 level at the peak alongside 2 of the rafters. You will then be able to use a saddle fan box to mount your fan. This box slides over the 2x4, and is only fastened using a set screw. You then use wood screws to actually fasten the fan bracket to the 2x4 behind the box, not the box itself.

enter image description here

PhilippNagel
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  • Really helpful, thanks! Looks like a perfect solution. – bill333 Jun 24 '20 at 02:14
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    Is that type of box legit for outdoor locations...? – Jimmy Fix-it Jun 24 '20 at 04:04
  • As far as I know, this would be considered a damp location. The box is under a roof. Any cover or device used would need to be rated for damp locations. I don't have a reference for that, so I may be wrong. – PhilippNagel Jun 24 '20 at 11:37
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    @JimmyFix-it Some locales would be OK with it if you used armored cable and a clamp. Since it has a knockout on the side, this should work since it's not directly exposed. – Machavity Jun 24 '20 at 12:38
  • OP also has not said whether there will be a finished ceiling covering this or not. – PhilippNagel Jun 24 '20 at 12:40
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    If you want this to be _really_ centered, continue your thought of using a couple of 2x4s (or 2x6s for additional stiffness) on _each side_ of opposing rafters, then run a 2x4 horizontally between the pairs. This will get the horizontal 2x4 directly centered under your peak and you'll be able to align the saddle box directly under it for as exact an centered mount as you can get. – FreeMan Jun 24 '20 at 13:56
  • Sorry, I should have made it clear about the roof. What you see in the photos is the underside of the roof. The exterior of the roof is cedar shake shingles and the peak is double capped copper. It is totally rain tight (it's been there for 10 years) but I guess it technically qualifies as damp since the sides are open. There would be no additional finish to the ceiling below what you see in the photo. The wiring would be in conduit (the source and switch are already in conduit on the pavilion uprights, and those passed inspection). – bill333 Jun 24 '20 at 17:56
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    Conduit = good. Exposed box that is designed to be inside the wall = bad. To do this properly you need an outdoor electrical box. This could be easily accomplished by mitering a 2x4 to span the rafters and surface-mounting a weatherproof box right in the middle under the peak, then running conduit to it. – Jimmy Fix-it Jun 24 '20 at 22:39
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Return that bracket and get a box only (no metal bar) rated for a fan. Run a length of 2x4 or 2x6 horizontally across from one rafter to the opposite one. Mount the box on the underside of this 2x. It will have no wobble and you can center it. You don't need bolts to attach this horizontal member; 2 to 4 screws on each end would do.

You might need an extended 18" down tube on the fan so the ends of the fan blades don't get too close to the rafters.

Jim Stewart
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