Ribs / roof sagging from a/c

[Shenandoah75]

Just bought our project. Plenty to fix but this was one I hadn’t expected / read about.

Ideas? Thinking reinforce the cross bracing from rib to rib ?

Also we’ll be converting to commercial use and I’m planning to add 1 and possibly 2 more units (replacing this one) . Would the better location for additional service be in the soacinga that’s shorter between ribs ? (Where the vents are now)

Thx in advance
-Brad

[Bubba L]

Absolutely. Rib to rib. I used 1.5 x 1.5 aluminum square tubing and just cut/shaped the ends to fit the ribs (probably overkill,but why not). So, one tube street side, one tube curbside and a couple fore and aft of the AC opening connected to the tubing. I have done it that way whether I had an AC or not. Someday someone may want to install an AC there and it’s ready. Good luck

[Coloradobus]

If your A/C unit is falling in, good chance you have rear end separation. Grab the trailer bumper and push/pull up and down to see if frame moves from body. If it is separstion, once corrected you A/C will pop back up.

[Belegedhel]

Welcome to the Forums!

I would say something is definitely going on that is more than just an AC unit and poor bracing. I have never seen an AC unit just smash the roof down like yours is. No doubt, putting in additional aluminum framing/bracing would help, but the fact is, your trailer was built just like thousands of others, and this is not normal.

Is the AC the original unit (ie., it is riveted to the roof around its large perimeter), or is it a modern version that "clamps" into place? I notice in the picture you have a row of gooped up rivets coming through the roof--what is that for?

The usual practice when installing a new AC, or replacing the original riveted on version is simply to put a 1.75" thick piece of wood fore and aft of the AC hole in between the interior and exterior skins so that the modern clamping mechanism has something to hold onto.

Your falling AC could be the result of too much travel on bad axles (yes, they are bad), rear-end separation (yes, you probably have this too), or a tree limb falling on the roof of the trailer, which the PO failed to mention.

good luck!

[Shenandoah75]

Definitely have rear end separation. Lots of daylight coming in back there (the pic above doesn't do it justice but shows a little. The plywood is pretty much rotted to nothing in the bathroom area...

I'm not 100% sure, but my guess is it's original (the fridge, furnace, water heater, and control panel all appear to be original if i had to guess as well). Similar line of anchoring /sealing on the rear side, no wood or other bracing. The rooftop unit seems massive compared to what i've seen (13.5/15K ) on my own post-2000 trailers. And the main box going up into the coils has no mechanical clamping at all.

thx again for all your inputs!

[Shenandoah75]

And thx for the welcome. I've been browsing / researching here for weeks along with Miller Garage's youtube channel and many others.

Exciting time for us. We've been RV'ing for 20 years. Always wanted an airstream, figured we'd eventually replace our current Jayco bunkhouse as the kids moved out. But we're looking forward to this project. Had been considering a Type D schoolbus or and Airstream for my wife's mobile kitchen and i think i made the right call regardless of the work ahead

[uncle_bob]

Hi

Another possible: Somebody put something really heavy up there. Not sure why anybody would do that. Going under an underpass and "catching" the original A/C is also a possibility ....

Bob

[4RXLA]

Had same issue on my 77. The air conditioner was only sitting on one rib and held in by rivets from the factory. Years of bouncing on bad axles led to the sag and a few frame cracks. Had metal bracing installed between the ribs to support the new unit and the sag is gone. Frame cracks plated and strengthened also.