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Old 07-05-2015, 02:31 PM   #1
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Roof Sag Quick and Dirty Fix

On a previous thread I showed how I pulled the ceiling up with a 2X2 tube on the roof and an oak board on the ceiling inside. Well, it worked for a while until I developed a small leak right under the rear end of the a/c unit.

Keep in mind this is a 37 year old TT a 78' Excel and I figured if I get 3 to 4 years out of it I can burn it to the ground and be money ahead. So quick and dirty works for me in this instance.

This TT was never designed to hold the weight of an a/c unit because the roof structure is only 1" thick and over the width of the TT (8') it just isn't strong enough to hold up that amount of weight without sagging over time.

As this is just a short term TT for us I didn't want to go to all the trouble of removing the roof to rebuild it and then it still would be only 1" thick.
I figured I could support the weight of the a/c unit using 2X2 tubing again spanning the width of the trailer and then pulling the roof structure up to the tubing from the inside with screws threaded into the tubing.

I decided to use tubing with a .185 wall thickness so I would have 5-6 threads for each screw to hold with for the ceiling uplift. 5 threads is generally thought of as being the value of the tension strength of any screw and 10/32 steel screws would fill that role.

Got the tubing welded up and painted (as shown in the first picture). After placing it on the roof it was aligned the way I needed and held in place with clamps from inside through the hole so I could drill upwards from the ceiling to match mark the holes in the ceiling to the drill marks on the bottom of the tubing. After the holes were drilled and pionts marked on the tubing I went up top side and flipped the unit over to finish drilling the holes and tapping them to 10/32. A little grease on the tap and an electric drill run slowly tapped the holes easily.

Because I had to have a seal between the roof top and the bottom of the tubing and the fact that I have a flat roof I couldn't just put the seal under the tubing and tighten it. I would still have a dip the thickness of the seal in the roof when done. I came up with the idea of using 3/4 inch blocks under the ends of the tubing to raise it enough to have a flat roof when the screws from the inside were tightened. You can see the blocks in one of the pics attached. It worked pretty well.

Much of the weight of the a/c unit is aft of the of the hold down bolts so I need to install a brace toward the back of the unit. Used a 3" tall Douglas fir board.

A new 2nd seal was installed on top of the frame and the a/c unit bolted into place (the bolts are way long enough to go the additional 2 1/2 inches).

The a/c unit is so old it actually has oilers for the condenser fan motor. I'm sure that has never been done if almost 4 decades! All the dirt and crap was blown out of the coils and innards of the a/c unit. Probably going to put a "hard start" condenser on it next week.

Its on and the install went well. A new shroud is on the way for next week.
You can see the first tubing in front of the new "H" tubing structure. The weight aft of the bolts on the a/c unit is what caused the 2" sag in the roof plus a small leak underneath the a/c unit.

BTW, Endurabond tape works wonders on old TTs.
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Old 07-09-2015, 06:48 PM   #2
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I like people who think outside the box. Well done!

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Old 07-09-2015, 09:42 PM   #3
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Old 11-09-2015, 10:15 PM   #4
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Could you explain how you used the tape?

Am I interpreting correctly? The screws into the new aluminum frame were to keep it in place on the roof. Installing the AC on top of the new frame and bolting the lower portion of the AC under the ceiling pulled the ceiling back up by using the for mounting bolts that secure the upper and lower portions of the AC unit to the top of the roof and bottom of the ceiling?

I didn't understand about the wood blocks in the photo, or how you sealed the screw holes in the roof. I do understand about a lot of the AC unit being behind the mounting bolts though....Bill
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Old 11-11-2015, 09:33 AM   #5
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The eternabond tape was used on the seam of the of the aluminum roof covering below all the seals and frames where the original leak was from.

The large screws used to hold the a/c unit on the roof run through the hole for the air to pass and are inside the foam seal rings so no water gets inside to the air transfer hole.

Because the roof is flat if I laid the steel ( it is steel not aluminum) frame on top of the foam seal and then put the a/c unit on top of that it would push the roof down creating a pool around the a/c unit. By propping the frame up on blocks at each end I can "pull" the roof up a little as I tighten the hold down bolts and it actually creates a slight hill to
prevent water reaching the a/c hole.
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