MaxAir vent in fiberglass roof

[Elmix]

I want to replace my roof emergency exits with MaxAir Deluxe vents. Of course, the vents are 14x14 and the exits are 23x23. I saw that some people just add steel sheets and supporting brackets. My roof is made out of fiberglass. Should I still use metal or are there any alternatives (I am a newbie in fabrication)?

[o1marc]

Most use a piece of sheet metal to close the hole and mount the fan in the middle of that. I instead used a piece of tinted Lexan and then mounted the fan in the middle. Not thay I've removed so many of the school windows and only replaced some with RV windows it's a bit darker in and I appreciate the extra light coming through much more now. Also replaced the front hatch and the passive vent with Lexan windows.

[Elmix]

Wow, I was just thinking about using lexan. How thick is your sheet? Also what did you use to secure it to the roof?

[o1marc]

Originally Posted by Elmix

Wow, I was just thinking about using lexan. How thick is your sheet? Also what did you use to secure it to the roof?

1/8" is all you need. Make sure it is Lexan and not plexiglas. I ordered 2-26" x 26" x 1/8" tinted gray Lexan on eBay from a seller "popdisplays" . I paid a premium for these knowing I would have too much "scrap" left if I bought a 4' x 8' piece. I used "cold" butyl tape and then stainless steel panhead screws, predrilled about every 2". Once I installed the screws using the impact I trimmed the excess butyl tape showing and then ran a bead of sealant around that. They don't leak. Trimming inside is going to be more work, but doable. 2 inside trim rings instead of one, one being fabricated.

[Elmix]

Thank you so much! I thought I’d need at least 1/4 of an inch. Actually, I have ordered already lexan sheets from this ebay seller. I want to make a front door out of lexan.