Replacing rooftop fan in Oxygen

[Dennis Sigut]

My old fan on the Oxygen needed replacing, so I ordered a new MaxxFan Standard 4500K. I removed the old fan and started to install the new one, but realized the new fan is slightly smaller in overall dimensions. The flange on the new fan does not cover the holes where the screws were on the old fan. It will cover three sides, but i don't know what to do with the remaining uncovered holes on the fourth. Fill them with butyl or Dicor gap sealant? Some kind of strip to cover that row of screw holes? Maybe I'm being too OCD, but even though it's on the roof and won't be seen, I want it to look and be a professional type solution to the problem. Any ideas will be greatly appreciated!

[wbullivant]

Originally Posted by Dennis Sigut

My old fan on the Oxygen needed replacing, so I ordered a new MaxxFan Standard 4500K. I removed the old fan and started to install the new one, but realized the new fan is slightly smaller in overall dimensions. The flange on the new fan does not cover the holes where the screws were on the old fan. It will cover three sides, but i don't know what to do with the remaining uncovered holes on the fourth. Fill them with butyl or Dicor gap sealant? Some kind of strip to cover that row of screw holes? Maybe I'm being too OCD, but even though it's on the roof and won't be seen, I want it to look and be a professional type solution to the problem. Any ideas will be greatly appreciated!

Hi Dennis
As long as there is sufficient overlap just center the fan and use new holes for mounting. You can fill the old holes with thickened epoxy as an extra precaution then use self leveling Dicor to completely cover the seam, screw or bolt heads, and old holes. Be sure to have all surfaces clean before applying the Dicor. It will look good and will not leak.

[Dennis Sigut]

Hi Bill,

Thanks for the reply. If I center the fan, nearly all the old holes will show. If I move it just a bit, I can get three sides completely covered, but it still leaves the fourth side holes uncovered. I am hoping to make it all look as original as possible, without filled holes, but your suggestion is probably the best that can be done. I appreciate your time and reply!

[wbullivant]

Originally Posted by Dennis Sigut

Hi Bill,

Thanks for the reply. If I center the fan, nearly all the old holes will show. If I move it just a bit, I can get three sides completely covered, but it still leaves the fourth side holes uncovered. I am hoping to make it all look as original as possible, without filled holes, but your suggestion is probably the best that can be done. I appreciate your time and reply!

The most important thing is to have a structurally strong mounting and that will probably be achieved by centering the fan in the opening. Once you apply the Dicor it will cover the extra holes and make them invisible. If they are visible from the inside then fill flush and use touchup paint.

[Dennis Sigut]

Good point. I'll have to check that when I have time to get back up on the Oxygen roof. Thanks!