When the rubber roof starts to deteriorate, you have two choices. You can either replace the rubber membrane material that protects the substructure of the roof, or you can re-coat the rubber roof with a special material designed to penetrate the pores of the original tired dirty rubber material.
Replacing the rubber roof would typically be the preferred option. The material itself is guaranteed to last ten years and under normal circumstances and care it should last fifteen to twenty years. However, replacing the material is a big job and not something that your average do-it-yourselfer would tackle. It's also an expensive job. Even doing it yourself, the materials would cost between $1,000 and $1,500 and it would be a three day job.
In most situations, the second option is preferable. Re-coating the rubber roof is a good do-it-yourself project that most people can accomplish at a cost of less than $400. If done according to the instructions, the re-coated roof should be good for a minimum of five years, and quite likely more than that.
A close up of Sherman's rubber roof. You can easily see that the exterior of the membrane has started to crack and split. This only happened in the last year!
The first step is to determine the type of material your roof membrane is made of. Most RV rubber roofs made since 1990 are EPDM rubber. This is the most popular type, although there are other types so confirm this first! Sure enough, Sherman's roof is EPDM rubber, so the following review is based on that fact.
Next, we need to research the different products available to do the job. I narrowed it down to two choices, and I believe that either one would do the job necessary.
One is called Liquid Roof and you can see it here...
Liquid Roof RV Roof Coating & Repair 1 Gallon
The other is made by Dicor who are the people who supply most of the rubber roof material to the RV industry. It's simply called Dicor EPDM Rubber Roofing Coating System and it is available here...
Note that the Dicor product is a two part system! If you purchase one gallon of material, you also need to purchase one quart of the activator/cleaner to go along with it...
I decided on the Dicor product for two reasons. One, Dicor is the company who makes the the rubber roofing membrane itself and supplies most of the new manufacturers. You would think that if they supply a re-coating material that it is designed specifically for that product! And two, the product reviews that I read made it sound like the Dicor product is easier to apply.
Ready to go!
Okay, so let's get to the job itself!
First, you need to check, replace, and repair any of the roof caulking that is used to seal the seams of the roof. This is very important, and needs to be done a week prior to doing the re-coating job itself. There are several manufacturers of RV roof caulking, but once again, I decided to go with the product made by Dicor...
Look for cracks in the caulking. Normally, these are cosmetic, but if left they will become a problem!
You need to dig out the old caulking, clean the affected area, and replace the caulking.
There. That's better!
After you've done the caulking, you need to wait a week for it to properly cure. Then, you need a clear day when it's not too hot and there is no rain in the forecast for the next couple of days. For us, that was yesterday!
The only downside for me was that the wind picked up, and ideally I wish it had been less windy.
The first step is to apply Part 1, the cleaner/activator.
The purpose of this chemical product is to clean the roof and open the pores of the material. You have a five hour window within which to apply Part 2 after you complete this stage.
They say to mask off the rest of the RV with plastic sheeting because there is the possibility that the cleaner/activator could discolor any graphics or paint on your RV. So I bought the materials necessary to do this, but I bought masking tape that was on sale and it wouldn't stick to the plastic sheeting very well. My mistake....buy good quality masking tape!! Secondly, it was too windy and the plastic sheeting was difficult to keep in place.
Roof edge masked off.
Sherman's front end covered with plastic.
(I should note that I did get quite a lot of the cleaner/activator on Sherman's side exterior and that it did not affect his paint or decals. I was quick to rinse it off with water though.)
Sherman is a 28 foot motorhome. The roof area itself is maybe 25' x 8' so perhaps 200 sq ft. Part 1 cleaner/activator comes in a one quart container that is supposed to cover 125 sq feet, so given that the roof also has three solar panels, two quarts should have been enough.
You put the product in an agricultural sprayer. Fortunately, I had one in the shop here.
Pump style sprayer.
Something like this would work...
Like I said, it was windy. And because of that, I almost ran out of product. Or, perhaps I was applying it too heavily. Either way, I wished that I had bought three quarts of the cleaner/activator instead of two.
You apply the stuff, and then leave it to sit for minimum 15 minutes.
Then, they suggest using a pressure washer to rinse it off. Certainly, this is the easiest way, however simply using a hose sprayer and a brush would have worked as well.
Fortunately, I had a pressure washer at my disposal!
You need to rinse the cleaner/activator off the roof to the point where there are no more soap bubbles coming from the rinsing. After that, you need to leave the roof alone until it is completely dry. For me, this took about 45 minutes.
Now, it's ready to re-coat!
Each gallon can of re-coating material needs to be stirred for a solid five minutes! Suggest you buy a mixing attachment for your electric drill! Once you've got it well stirred, you're ready to go.
You need a brush first, to go around all of the areas where a roller won't do the job. Around the vents, skylights, and solar panels, and edges. Simply lay on a fairly think coat.
Kevin, up on the roof doing the edges.
Right away, as soon as you're done the edging you can get up there with a roller and tray and it's the same as painting a wall in your house except you can put the product on fairly thick.
I found that it skims over really quickly, although that might be because I was in a very dry environment, with some wind, and a bright sun. Obviously different environmental factors will affect the cure time, but it was almost drying too quickly.
After you are finished the first coat, you need to wait until it's dry enough to walk on again. I waited about an hour before I went up to do the second coat.
Again, I put on what I thought was a fairly thick coat. The instructions say that 1 gallon covers 125 sq ft and that two coats are required. So based on that, I should have needed three gallons. But every review that I read said that they had too much product left over. So I bought two gallons...and still I had a half a gallon left over and I'm certain that it's on there thick enough. So judge your own purchases accordingly.
I'm glad I have left over though. You can re-coat any areas you missed within 48 hours and still have it adhere properly...so I will go up and re-inspect and touch up today where necessary.
It took me exactly five hours from start to finish, including drying times. You're supposed to organize yourself to start this job after the morning dew has disappeared off the roof, and so that there is still three hours of sunlight left at the end of the day so that in can cure before the evening dew begins.
The consistency of the finished product is a little different than what I expected. I thought it would have flowed a little more, but perhaps that's because it was drying too quickly. It's definitely rubbery like, but you can see the brush and roller marks if you get close enough. Perhaps I'm being too fussy! Still, it's a 100% improvement from what I had before, and I wouldn't hesitate to recommend this as a good home handyman way to extend the life of your roof.
Only time will tell now as to how good the product is. Hopefully I'll be able to update this article as time goes on to be able to say how happy with it I am!