I have a 1997 Coleman Sun Valley with the dreaded ABS roof. Overall the roof was in fairly decent shape except for one major thing: serious sag. Unfortunately I don't have any photos of how bad it was, but we're talking at LEAST a 4.5 -5 inch sag in the middle of the roof, especially around (and likely in large part due to the weight of) the air conditioner. This substantial sag in roof led to another problem: a water leak around my AC unit as water pooled on the roof when the AC was used & spilled over the top of the gasket & into the inside of my newly remodeled camper! After a bit of research on the Pop Up Portal & YouTube, I knew what I had to do! Off to Menards to buy some Uni-strut, Uni-Strut plates & bolts & spray paint. Supplies came to $160. Below are pictures of the internal bracing system we installed. Luckily I have a friend who is handy with a welder. After I sent him some photos & videos of what I thought needed to be done, he was willing to take on the job. Basically the two end pieces were welded to fit the arch of the roof & screwed to the metal plates on the lift system at the ends of the camper near each bunkend first. This was the most time consuming part of the project because it was important to measure the angles & get the first piece just right. After that things went quicker. The beauty of this bracing system is that we never had to drill any new holes into the ABS roof. Normally the camper door fits into glides & snaps onto the ABS ceiling when not in use & the camper is folded down. These glides, snaps, and also the cord channel for the AC unit had to be removed so that the two lengthwise Uni-Strut braces could fit flush against the camper ceiling. On my Sun Valley model the cross piece of Uni-Strut on the couch end of the camper ran into a fold-down clothes hanger. We just cut a notch in the Uni-Strut to accomodate it. The clothes hanger is no longer useable, but it seemed like a small price to pay for a roof that doesn't leak. After the lengthwise braces were attached to the crosswise pieces with the Uni-Strut plates & bolts, a simple A-frame suport was made out of scrap 2x4's with a leftover piece of Uni-Strut attached to the top. This support was then placed underneath each lengthwise brace & the roof was then jacked up & tightened into place using an ordinary hydraulic car jack. My own opinion is that it's important to try to do this on as hot a day as possible so that your roof is its most malleable from the heat, giving you the best chance of jacking it up without cracking the ABS. On the day we actually jacked the roof up the temperature was in the low to mid 90's. (Welcome to summer in August in Iowa! Lol) One of the things I didn't like when I talked to commercial camping outfits was that the very few who were even willing to look at my roof problem would only consider it as a winter job. To me, trying to jack up an ABS roof in the winter in Iowa, even if it was in a heated garage, sounded like a great way to crack my roof & then have to sell me either a new roof or a whole new camper, (which all of them had already tried to do at least once when they heard what my problem was anyhow.) NO THANKS! This is part of what gave me greater incentive to try & fix it myself with the help of my welder buddy, & I'm so glad I did! All in all, the project took about 20 hours, which included shopping, measuring, drawing the angles on computer software, cutting & welding the Uni-Strut, spray-painting, sanding, removing the door & AC cord glides from the camper, final installation & jacking up the roof. Being a first -time try, if it had to be done all over again, I think it would probably only take about 12 hours. I am THRILLED with the results! There is ZERO sag around the AC unit now & at its worse spot, there is maybe only 3/4 - 1 inch of sag left max, where before it was easily 4-5 inches of sag. Best of all, the roof drains as it should & no more water leaks! Now I'm on to my next roof project: MEK & ABS pellet repair for a few minor hairline cracks around the edges of my NON-sagging ABS Coleman roof, & a beautiful coat of bright orange Grizzley Grip for a whole new sun-resistant, crack-free look. I'll let you know how it turns out! I hope this helps anyone who might be thinking of tackling their own sagging ABS roof. Trust me, for easily less than $200 it's TOTALLY worth it!