For those thinking of doing a roof coating, I'll throw out a few things to consider when doing a roof re-coat in case you have not yet thought of them.
Even the 2007 model year Sunlines (the last model year made) now have a good amount of years on them. The older a camper gets that has lived outside a good portion or all of it's life, has other roof wear/sun damage beyond the worn white layer on the rubber membrane. The re-coating systems resets the rubber white layer decay issue. However other roof parts also have limited life from the sun damage. Ideally you reset the whole roof system wear clock when doing a re-coat if you have never addressed those areas before. Here are some of the things to look over and access before doing a roof re-coat.
1. As Kirkcomer stated, the Dicor lap sealant needs to be in top shape before a roof coat. Once it is cured, then you can coat over it. If the caulk has many cracks in it, it is toast. With a heat gun and a scraper, the old caulk can come up without much effort and then reapply fresh new caulk. You do not have to do the whole roof caulk at once, you can do it in stages. Just plan ahead enough as it does take time. Any hair line cracks, you can caulk over them. The old caulk must be cleaned thoroughly before applying new or it will not bond correctly.
2. The shower dome, they are very well sealed to the roof and caulked. That caulking will be coated over with the re-coat. I have seen several of these domes crack in a 10 year period living outside all the time. The cracks start mostly at the screw area and then the crack runs inwards from there. Consider the age of your shower dome and when do you plan on replacing it? Before the roof coat or after? If you replaced it a few years ago, OK coat over. If it has been on for more then 10 years, it is prudent to change before a re-coat as it may not last another 2 to 3 years.
3. The tank pipe vent covers. The ones that are plastic can last a little longer then the shower domes, but if they have not been changed in the 12 to 15 years, they will be due soon. Again the coating will go over the caulk sealant, new or old.
4. The 14 x 14 crank up roof vents. The actual covers are plastic and can be replaced without disturbing the roof. The metal frame is sealed to the rubber roof. If there is an amount of rust on the frame, consider when are you going to replace it? A note on this, on the 2004 model year campers, built from late 2003 until mid 2004, Sunline had many bad batches of roof vents. Lucky me, I happen to have a collection of 2004 Sunlines and every one of them had the metal flanges rotted out very early. With my first new camper, Sunline was in business then and sent me 3 new ones to install under warranty. All the others, I had to do on my own. The model years prior and after when they got the new vents under control, are not so much an issue. Point being, check for rust.
5. The fridge vent bottom base. The top cover can break down in the 10 years from being sun baked and can be replaced without issue. The lower base is sealed to the roof but can go longer as it is not exposed as much to the sun. Check it for brittleness or cracks. I do not have a good timeline on when the bases die. Since I end up doing more roof replacements, all roof mounted items get replaced short of the AC unit. My T310SR has the original base going on 16 years now and is still in good condition. But I 303 UV protectent treated it 3 to 4 times a year and that really helps all roof rubber, plastic, caulk things last longer. I would say a 15 to 20 year period may be a target if the camper lived in the sun all its life.
6. To the topic of removing AC unit from the roof or not when doing a roof re-coat, this decision will come down to a personal choice as it is somewhat more involved. The rubber under the AC unit is often very dirty as you cannot get in there to clean it. The degrading of the white layer is less as the sun cannot get in there either. If you decide to remove the AC unit, you need to buy a new roof gasket for the re-install. This post can help show how to do an AC change out and what is involved. https://www.sunlineclub.com/forums/f...ics-17066.html
7. Not knowing how long you plan to keep your camper, doing an Eternabond roof seal treatment on all the joints over the top of restored/corrected Dicor caulk is good step to help insure you do not get future leaks. There is cost to the material and it will take time. But it will make your camper more leak free from caulking sealant failures. This needs to be done before the roof coat so it bonds to the actual rubber and the aluminium trim. This is the process I am referring too. Other club members have also done this. https://www.sunlineclub.com/forums/f...ics-11610.html
8. Before you start the coating process, suggest you do a bleach cleaning to the roof to kill and remove all the mold spots. If you you do not do the mold kill treatment, the mold can still grow under the coating in some cases. If you need help on how to do the bleach clean, just ask. Dicor has instructions on this too.
9. Make sure you do not have any active roof leaks or old leaks that may have dried up. If you feel the rubber and an area feels like a rubber band/tire tube feeling, (check the whole roof, especially all around the perimeter) that super spongy feeling comes from the corrugate substrate under the rubber being deteriorated. Sunline nicknamed the substraight, bud board which will deteriorate when it gets wet and separate from the rubber leaving it like a rubber band feeling. While the whole Sunline rubber roof has a softer feel to it, the rubber band/tires tube effect only comes from water damage at sometime in the roofs life. An old leak what was stopped by new sealant still leaves the damaged and the rubber more vulnerable to failing from being supported. Coating over a bad spot in the roof with a damaged sub-straight under it, is not really going to make the stop roof leaks long term. Fix the roof area damage and then re-coat.
All of the above I mentioned do not have to have to done before a roof re-coat, other then Eternabond, roof damage repair and the mold kill bleaching process. The others items can be done in the future and you just have to touch up the coating that you had to remove to replace the roof item. I am just mentioning these items to consider. If you are investing on doing a roof re-coat, you are considering keeping the camper a longer time. Review each area and make a conscious decision to let it go or do it before the roof re-coat.
Hope this helps