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Old 02-03-2014, 06:56 PM   #1
Senior Member
Join Date: Aug 2011
Location: Albany, GA.
Posts: 917
Another leaky roof problem

This is a problem I have with an '05 FR Grand Surveyor 30 footer. I had to replace the A/C unit last year and when I got the old unit off I cleaned the area around the 14" x 14" hole the A/C sits on really well. I had been told to do this: At that time I took a piece of twine (actually new chalk line twine), tied about a two pound weight to one end and let that hang off of one side of the unit. I pulled the string rather tight, tied another weight onto the other end and let that hand off of the other side. My roof had a sag in it that was one and one-quarter inch (1 1/4") at the two points on either side of the 14" x 14" opening. My A/C unit is in the center of the roof as measured from side to side. While the A/C unit was off I also checked the roof build-up material for water intrusion and actually I did not find any dis-coloration from water intrusion. The roof appeared to be a rubber membrane, on top of what I know as "luan plywood (very thin) then about 1 1/4" of styrofoam, then the interior ceiling material. This is a ducted A/C so it has the "ducts" cut into the styrofoam. I checked the flatness of the roof this way at the sections before and after the A/C opening and they were not sagging. From all the internet searching I have done it appears that this sag is caused by the weight of the A/C unit on the roof and the roof sort of "bouncing along" as the camper rides along the roadways and this will eventually "weaken" the roof as time goes by. Made sense to me. A friend of mine who had worked on RV's helped with replacing my new A/C unit and he came over with some type of putty made into a roll, like tape. He swears that when he has used this before installing the foam seal for the A/C he has better luck with preventing leaks so we used the putty stuff and the foam seal. So far no leaks during rains. BUT---this past weekend I noticed something new: I was in a place where we had three (3) straight days of a light mist/fog type weather at a car show. I set up on Thursday morning and on Saturday afternoon one of my buddies brought it to my attention that I had a leak that was dripping off of my TV antennae handle. This was a very slow drip and I tried moving the handle to different positions with no change in the drip. Later he noticed that water was leaking from one of the lights in the ceiling of the camper. These are 12 volt DC lamps by the way. I took this light fixture off and the water was coming out of the hole made at the factory for the wiring. I then removed the TV antennae UP/DOWN handle and the rotation handle and sure enough the water was coming from the hole made into the ceiling material. This told me that the leak was somewhere else and was traveling within the ceiling. I then backed my truck up to the side of the camper, stood on my cooler on my tailgate so I could see the top of the roof of the camper. YEP, water pooled all around the A/C unit and what was on the rest of the roof was slowly running off. I raised the front of the camper a bit and the water started running off from around the camper. The leaking inside stopped about two hours later. After getting home I set the camper up with the front end up and put my de-humidifier in it to help dry it out. Three questions have come about from this: 1) I looked at other camping units at this car show and noticed that ALL motorhomes and ALL fivers had crowned roofs (from side to side) but NONE of the TT's had crowned roofs. Why don't the manufacturers make TT's with crowned roofs to facilitate drainage? 2) Does anyone know of any way to reinforce a camper roof from the inside so the roof does not sag under the weight of the A/C unit? 3) Does anyone have any idea of the weight of the panels, either total weight per panel or weight per square foot, used for the ceiling/roof of a travel trailer? Thanks, David

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Old 02-03-2014, 07:15 PM   #2
Join Date: Aug 2010
Posts: 796
The roof on my RockWood TT was crowned,(well, it was until a large metal beam flattened it out) not sure if they all are but I would imagine most are.
To support the AC unit sounds like it would require some structural mods, may have to remove paneling inside and cut into styro to add bracing. Otherwise it will probably only get worse. I wonder if this unit had previous damage? Does not make any sense for water to be pooling around AC unit, if this was to happen in ANY RV you would have leaks everywhere as the AC unit is just held on by a few bolts that kind of sandwiches the roof material between upper pan and lower fascia/control panel, not at all a hermetically sealed joint.

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Old 02-04-2014, 12:46 PM   #3
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Join Date: Aug 2011
Location: Albany, GA.
Posts: 917
@ RhoZeta: Imagine that the roofing panel your A/C unit sits on has gradually, over some time period, has began to sag probably due to the weight of the A/C unit. This would allow water to accumulate around the area that the A/C unit sits. Placing an A/C unit on an RV roof, using the proper seals, and tightening the bolts adequately does not always create a leak proof seal, especially if water pools around the seal. I'm going to look into a way to add some type of aesthetic support to the interior roof of this camper so the panel the A/C unit sits on is as flat as the other panels on the camper. IF the weather here ever breaks and we can get a couple of dry days. I went out this morning to look at the roof and there is water puddled at the front of the A/C unit. With the camper tilted back most of the water from this light misty rain is running off.
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leak, roo, roof

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