Installing Rooftop A/C using existing hatches

[AlleyCat67]

Has anyone installed rooftop A/C units this way? Is it even possible? Or would it be better to cut another hole for the A/C unit?

If a thread already exists for this, if someone could kindly point me to it I'd be ever so appreciative.

[scootie]

your hatch is I think 24x24" The standard hole for rooftop a/c is 14.5"x14.5"
not sure about another thread, but basically you need to remove emergency exit, cover with sheet steel, brace new Rough opening @ 14.5" weld sheet steel to roof, cut out new 14.5x14.5" hole, then used a few self taping screws for fun, generous elastomaric and roofing tar, making sure they are sealed good. then you should be good for 15 years or so before you leak or have to reseal.

I used a piece of old ceiling material from the inside if you are taking yours down, this is great material, and the cost is right.

[1olfart]

You may be able to get some ideas from the RV sights. Airstream & Avion come to mind. I have replaced the A/C on my Avion, and believe I remember seeing where others had modified vent openings.
good luck

[Justin McCormick]

I am actually going to do this very thing this weekend. Just as scootie described. However I do need to check the hole size. I thought it was 14x14, not 14.5 x 14.5.
Most AC units I have looked at read "This unit fits standard 14 x 14 Air Vents"

[AlleyCat67]

That tells me what I suspected would be the case, but was hoping I could get away with it as-is.

In either case the A/C is a project for next spring... gonna use a swamp cooler for the remainder of this year, until I need to bring in heat.

And yes, the metal ceiling is most likely coming down to insulate the inside... I wonder if I could get away with just using screws or rivets through the existing holes and just caulk/tar the hell out of it....

Or maybe take a welding class somewhere, I know there are gonna be other things I need to fabricate that will need strength....so that may be a good skill to have once I get good at it.

Thanks for the input.