Lessons from roof repairs (your mileage may vary)
Over the years I have had to make a few repairs to my rubber roof. It's been a learning experience. I thought I'd share as it might help someone along the road. I'm not claiming to be an expert. Just a guy who has observed some things.
When I bought my motorhome it had just been recoated by the person I bought it from. He used the products from CW. He scrubbed down the original roof with the pink stuff and then used the liquid rubber. I figured I was in good shape. Not so. That rubber came off in sheets. It trapped water under it. It was a hot mess. I cut it all off and allowed it to dry really well. I used EPDM liquid rubber to recoat the entire roof. The product I used was in a five gallon bucket and not specific to RVs. So far it has actually done pretty well for several years.
http://www.epdmcoatings.com/liquid-rubber.html#sthash.qOC54vc0.dpbs
When I covered it the first time (for me) I used eternabond tape over places where the original rubber was damaged. If I had it to do over I would not do that again. Over the years, as the sun has dried the EPDM rubber, cracks have formed around the edges of the eternabond tape. I think the tape is great around vents and such and for repairs that are emergencies or that you don't intend to cover with new rubber. But, if you're going down with a new rubber coating I wouldnt put it on cuts in the old rubber.
While I'm on the topic of eternabond tape. When I was repairing the roof for the first time I discovered that eternabond ain't so eterna if water has been trapped under it for a while. I pulled up some that had lost all of it's ability to seal or stick to anything. So, if you use it on a place where it seals and water never leaks under it you're good. Keep an eye on it over the years just to be sure.
While I'm on that. I have an older class A, 1990. I find that I need to inspect the roof at least twice a year. I actually do it more than that. When inspecting the roof take your time. If you have an older RV with a rubber roof you will need repairs at some point. What I have found is that the issues start with really small cracks in the rubber. If your not looking closely you will totally miss it. Although these little cracks can leak in a rain they can get bad in a hurry in the snow. As it melts water just sits on the hole and gets between the rubber and the plywood underneath. Then it seperates the rubber from the wood, traps more water, and the problem grows faster.
So, about twice a year I climb up on the roof with a tube of EPDM lap seal from CW. As I do my walk around I put a dap of lap seal on anything that looks like a problem.
Speaking of problem areas. What I have observed is that a typical weak spot for rubber roofs is where the rubber is stretched over the edge of the roof on the sides. You can have a leak here and not see it by simply walking around plus, it seems to want to tear there. If you catch a tree limb it can cut through the rubber and you not know it. This will pretty quickly cause delamination issues if left unsealed. This is where eternabond tape works great. Just be sure not to put it over trapped water.
About trapped water. Not all trapped water is created equal. In a hot summer in direct sunlight water might find it's way out of a "trapped" location. If it has found it's way to a place where your seeing it dripping down the interior walls or ceiling then it will may have the opportunity to dry on it's own. For the most part, water trapped someplace in an RV will eventually dry if you get the leak stopped (or get the RV out of the weather). A huge majority of RVs are parked outside all the time so weather has a big impact on shedding "trapped" moisture. So, with that said, I think that the most critical time of year to inspect your roof is late summer, early fall. In my view knowing your roof is good before the weather gets cold is very important. EPDM rubber wont dry below like, 50 degrees. It will shed water as soon as you put it down but, it will stay sticky all winter. And, trapped water doesn't dry as well in the cold and wet.
You can get a big roll of EPDM rubber, pull up the AC unit and all the vents and totally replace the roof with a brand new sheet of rubber. But, there comes a time when the cost benefit analysis doesn't justify that much expense and effort. There is no way I will ever do that on my old motorhome.
Lastly, make sure before you do anything on your rubber roof that you know what kind of rubber it is. There is basically EPDM and TPO. Although EPDM liquid rubber will work over TPO it may not be the best choice. But, only EPDM will work on EPDM. Dont even get up there with a tube of silicon from Lowes. It might work for a trip to the beach but, at the end of the day it will just be a mess. If you have a rubber roof pick up some lap seal the next time you go to Camping World. I keep at least one tube on board all the time. By the way, when it's freezing cold out it's an aggravation to work with. And be careful up there. If you fall off of your RV that might be the end of camping and no one wants that.
When I bought my motorhome it had just been recoated by the person I bought it from. He used the products from CW. He scrubbed down the original roof with the pink stuff and then used the liquid rubber. I figured I was in good shape. Not so. That rubber came off in sheets. It trapped water under it. It was a hot mess. I cut it all off and allowed it to dry really well. I used EPDM liquid rubber to recoat the entire roof. The product I used was in a five gallon bucket and not specific to RVs. So far it has actually done pretty well for several years.
http://www.epdmcoatings.com/liquid-rubber.html#sthash.qOC54vc0.dpbs
When I covered it the first time (for me) I used eternabond tape over places where the original rubber was damaged. If I had it to do over I would not do that again. Over the years, as the sun has dried the EPDM rubber, cracks have formed around the edges of the eternabond tape. I think the tape is great around vents and such and for repairs that are emergencies or that you don't intend to cover with new rubber. But, if you're going down with a new rubber coating I wouldnt put it on cuts in the old rubber.
While I'm on the topic of eternabond tape. When I was repairing the roof for the first time I discovered that eternabond ain't so eterna if water has been trapped under it for a while. I pulled up some that had lost all of it's ability to seal or stick to anything. So, if you use it on a place where it seals and water never leaks under it you're good. Keep an eye on it over the years just to be sure.
While I'm on that. I have an older class A, 1990. I find that I need to inspect the roof at least twice a year. I actually do it more than that. When inspecting the roof take your time. If you have an older RV with a rubber roof you will need repairs at some point. What I have found is that the issues start with really small cracks in the rubber. If your not looking closely you will totally miss it. Although these little cracks can leak in a rain they can get bad in a hurry in the snow. As it melts water just sits on the hole and gets between the rubber and the plywood underneath. Then it seperates the rubber from the wood, traps more water, and the problem grows faster.
So, about twice a year I climb up on the roof with a tube of EPDM lap seal from CW. As I do my walk around I put a dap of lap seal on anything that looks like a problem.
Speaking of problem areas. What I have observed is that a typical weak spot for rubber roofs is where the rubber is stretched over the edge of the roof on the sides. You can have a leak here and not see it by simply walking around plus, it seems to want to tear there. If you catch a tree limb it can cut through the rubber and you not know it. This will pretty quickly cause delamination issues if left unsealed. This is where eternabond tape works great. Just be sure not to put it over trapped water.
About trapped water. Not all trapped water is created equal. In a hot summer in direct sunlight water might find it's way out of a "trapped" location. If it has found it's way to a place where your seeing it dripping down the interior walls or ceiling then it will may have the opportunity to dry on it's own. For the most part, water trapped someplace in an RV will eventually dry if you get the leak stopped (or get the RV out of the weather). A huge majority of RVs are parked outside all the time so weather has a big impact on shedding "trapped" moisture. So, with that said, I think that the most critical time of year to inspect your roof is late summer, early fall. In my view knowing your roof is good before the weather gets cold is very important. EPDM rubber wont dry below like, 50 degrees. It will shed water as soon as you put it down but, it will stay sticky all winter. And, trapped water doesn't dry as well in the cold and wet.
You can get a big roll of EPDM rubber, pull up the AC unit and all the vents and totally replace the roof with a brand new sheet of rubber. But, there comes a time when the cost benefit analysis doesn't justify that much expense and effort. There is no way I will ever do that on my old motorhome.
Lastly, make sure before you do anything on your rubber roof that you know what kind of rubber it is. There is basically EPDM and TPO. Although EPDM liquid rubber will work over TPO it may not be the best choice. But, only EPDM will work on EPDM. Dont even get up there with a tube of silicon from Lowes. It might work for a trip to the beach but, at the end of the day it will just be a mess. If you have a rubber roof pick up some lap seal the next time you go to Camping World. I keep at least one tube on board all the time. By the way, when it's freezing cold out it's an aggravation to work with. And be careful up there. If you fall off of your RV that might be the end of camping and no one wants that.
