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I want to mount an industrial fan in my shed.

Because of its dimensions, the only option seems to fix it on a wood beam that run around the shed near the top (see the red square on the picture):

View of the shed's wall

I'm not sure of the type of wood, but the same type of beam is used for holding the roof so I guess it should support the weight (its section size is 95mm x 45mm).

My questions are:

  • Will the beam be strong enough to support the 21 Kg fan (I guess it should, but I'd appreciate a more qualified answer)
  • What should I use to fix the fan (the metal plate provided features two 14mm holes; see picture bellow)

Fan and its fixation plate

EDIT: Here is what I'll do after taking advantage of the great advises I received:

What it should look like

Note that I moved the fan to the left since the first draft; That's where I wanted it in the first place but because of the vertical placement constraint there wasn't enough ceiling clearance.

Feel free to make remarks if I missed something important (I'll try to find a 3/4 inches plywood board for the vertical support).

  • Will the circumference of the fan enclosure fit under the roof panels? Also, its' not oscillating is it? – ojait Jan 31 '16 at 16:54
  • @ojait I checked and it does fit. It has an oscillating feature configurable between 0 and 90 degrees so I can prevent it to bump into anything (also the oscillating move is slow enough so I don't think it would have an effect on the forces applied to the support) – LeFauve Jan 31 '16 at 22:20
  • @LeFauve- as a last minute suggestion, if you need more fan blade clearance or want the fan directed towards the floor, you could cut wood shims (tapered or angled) to mount behind the fan plate. This would direct the air down to the floor and also lower the top of the fan by pivoting it away from the roof . – ojait Feb 1 '16 at 16:06
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(1) The fan as shown in the photo is upside down. Mounted in this position, the weight of the fan will pull the plate away from the beam. Turn it over so the weight will push the plate against the beam.

(2) The beam will hold the fan but the weight will apply a twisting force to the beam.

To overcome this, you should mount a board vertically from the beam to another anchor point, perhaps the steel beam directly above. Mount the fan on the vertical board, not directly on the beam.

Alternately you may be able to brace the fan mounting with a chain or other tension member between the end of the fan mount arm and the steel beam directly above.

Of course I'm not there so you'll have to identify and calculate the forces yourself.

(3) If you can, use through bolts with fender washers rather than large wood screws.

  • Thanks for raising (1). The fan is supposed to be mounted on the other side, but since the mounting head is perfectly symmetrical I assumed it could be mounted in both directions. I fail to see why the forces will apply differently but I'll take your word on it. For (2) there won't be enough room between the beam and the steel beam but there is another wood beam bellow the one on the picture. That would also allow me to address (1) and mount the support up side up. Now, what kind of board should I use? I'm tempted to use a steel plate, but I'm not really sure where to find one... – LeFauve Jan 31 '16 at 22:41
  • (3) through bolts weren't an option but if I'm using a board that should now be possible. – LeFauve Jan 31 '16 at 22:43
  • @LeFauve-Steel plate isn't necessary. A large square of thick plywood is the best mounting base . Attach it to any wood framing you've installed with exterior screws of correct proportion. Then bolt the fan bracket to it. – ojait Feb 1 '16 at 0:31
  • @ojait could you be more specific about how thick the plywood should be? Would half an inch be enough? – LeFauve Feb 1 '16 at 2:24
  • @LeFauve- I'm sure a half inch piece along with the proper carriage bolts and washers, would be adequate. 3/4 inch is better or (2) half inch plywood sections also would be best. – ojait Feb 1 '16 at 2:30
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The wood framing member looks to be similar to a 2 x 4 (inch) commonly used here in the States as wall studs and such. From what is obvious from the photo that leads me to believe it will support the almost 50 pound fan is the wood top plate is on edge rather than oriented on its' face (flat). The wood plate is much stronger in this direction and can with stand more compressive load.

This bearing strength will also depend on the length of the board and how and in what locations it is affixed to the rest of the building. The greater the length the easier it will be to compress the wood causing it to fail (break). To compensate for this the board is fastened to other parts of the building probably with specific screws. The sheet metal walls. vertical "I" beams and rafters and the diagonal stabilizing rods all connect together to form a rigid system.

I would verify that the wood plate is fastened with enough fasteners so that the wood can't be twisted vertically by the weight of the fan mounted to its' face. If in doubt install similar dimensioned lumber to the underside of the horizontal plate (so as to be oriented vertically) to prevent it from twisting. I would also try to build any extra support pieces off of the steel beams shown in the photo. Attaching the fan to framing that is only attached to the sheet metal walls will most likely work loose.

Finally, once any additional supports have been installed attach the fan bracket with carriage bolts of appropriate size. Use flat washers on both sides of the bolts and a split washer in between the nut and washer.

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