AC Install - New hole prep

[ashamsuddin]

I have a travel trailer and am adding a Coleman Mach 8 Cub AC unit.  I currently only have a vent fan.  It appears that there is already a location marked on the roof to cut a new whole for an AC unit.  In the ceiling below, near the same location, there is existing wiring (one of those fake outlets with a power wire going to it).  Seems like a pretty straight forward process to install from the videos I've seen thus far. 

My only questions are on the preparation of the hole. 

#1 - I've seen some just cut a 14" square right through the roof material, and others slice and peel back the material so it can be stapled down into the hole.  Is that necessary?

#2 - Most install videos I see (most are replacing an existing AC unit) have a hole that is framed in with wood, but what if, when I cut the hole, all I see is the styrofoam insulation?  Do I need to make a frame of some sort, or is the exposed insulation fine?  Or, since the trailer was obviously designed with an AC unit install in mind, might it already be framed once I cut into it at the marked location?

Just hoping to hear from someone who's "been there, done that" before I take a jigsaw to my trailer.  I've attached a picture of the area on the roof that seems to be marked for an AC unit.

 

[Rene T]

What makes you say that's a mark for a AC. Looking at the picture, the roof is pretty dirty and that it would be hard to tell.  I would do a good washing of the roof with a mixture of soap and bleach. If it's just a spot, it may wash off.

 

[HueyPilotVN]

Use the existing fan location and replace it with an A/C.

 

[SpencerPJ]

I would frame it, if not, it might sag, not drain well, get water in roof, and great a really ugly situation.  The 'X', I don't see it.  I do see cross braces that could be framed into.  I would slice and tuck the roofing into the hole on the roof.  Maybe get up there with a stud finder and have better thoughts.  I highly doubt that it is prepped for AC, that costs $$, and in RV production, it's not typical.  I have a friend the added AC to pop-up.  He's OCD  (lol), but he added interior braces to the ceiling to help support AC.

 

[Rene T]

If you are determined to cut a hole, I would do the roof last. Cut a hole in the ceiling about 6" diameter. Then reach in the hole and pull out the insulation. If you do find that the hole is already framed, open up the ceiling hole to the framing. Then drill small holes from each corner up through the roof material. Then make an large X from hole to hole on the roof and cut it. Then you can let the roof material fall into the hole, staple it to the framing then cut off the excess.

 

[Rene T]

I highly doubt that it is prepped for AC, that costs $$, and in RV production, it's not typical.

You could remove the blank face plate and check for voltage. If there is, go to your entrance panel and see if there is a circuit breaker labeled/designated for a AC. Shut it off or on to verify you do or don't have power at the wires.

 

[ashamsuddin]

Great suggestions.  I'll definitely open a hole underneath first to test my theory.  I had to reduce the quality of the image quite a bit to upload.  If you zoom out you can see the "square" on the roof clearly.  Maybe I'll just ask Camping World for an "estimate" on an AC unit, and have them explain to me what all they'll have to do to complete the install, and go from there. 

 

[Gary RV_Wizard]

I can see the outline of what appears to be the under-framing that would support an a/c. Without that framing, sagging would be all but assured. Still, I would proceed cautiously as others have suggested.