Installing ceiling fan with joists too close apart for ceiling brace kit

[Frank]

I am trying to install a ceiling fan (about 17lb). The outlet box was plastic and probably not rated for ceiling fan so I have it knocked out and was planning to use a ceiling brace kit. However I noticed that the joists was too close apart and the bar of the brace kit is too long. One joist is flushed to the edge of the hole. I wonder if I can just screw a metal outlet box to it. Will that be strong enough as the support is going to be only on one side of the outlet box.

[None]

Yes you can, here is one type of box designed specifically for the job.

If you use a regular box, don't use the black drywall screws to attach it, use deck screws, they are much stronger and less brittle.

[Ed Pawlowski]

Not sure I understand. You want to use one support and then screw the box directly to the joist on the other side? That can work if you use a long enough screw. If it is attic above, you may be able to reinforce from above too.

[Mr.E]

Use construction adhesive to add a block to the side of the joist and screw the box to the joist and the added block.

[Clare Snyder]

Or just run the support bar between the joists at an angle allowing the support to fit between the joists????