As much as we might like to talk about sleeping out under the stars and the good old days of camping, most of us have discovered that RV roofs are a great benefit. RV roofs are designed to protect us from the grief of bad weather, keep the leaves and pine needles out of the bed and still maintain their integrity while being driven down the road in excess of hurricane level winds, Richter scale 6 or better earthquakes, the baking sun, acid rain and impacts from trees and other low overhead obstacles.
RV roof leaks can confuse the dickens out of even the best RV technician. A leak coming through the ceiling in the rear of the RV could originate in the middle, the side or even in the front of the unit. Patience and attention to detail are the keys to a successful roof repair.
There are 3 main types of RV roofing that we need to deal with, Fiberglass, sheet metal and EPDM rubber. The newer molded sheet plastic type really doesn’t take any maintenance except for staying the heck off of it ! (Course ya still gotta check the places where pipes, vents and AC Units go through them – )
The first successful RV roofs were made of thin sheet metal pieces. These roofs were designed to “float” on a lightweight rafter system. This helped to reduce leaks caused by the expansions and shrinking of the metal due to temperature changes. While this system did what it was designed for, the light construction was not designed to support the weight of storage pods or an adult walking around. These early roofs still had leaking problems due to flexing of the RV in normal usage which over a period of time could open-up the joining seams in the roof. Later versions used a continuous metal piece from the front of the RV to the rear. This roofing system only required seams on the sides where the roofing met the four walls and where the roof was opened to install vents, antennas, air conditioners and so forth. Units built up to the around mid 70’s were still based on the “floating” support design which was rather weak but greatly decreased the number of places that the roof could leak. Modern metal roofs of the last ten years are normally walk-on capable.
The repair of metal roofs is straightforward and easy so long as the metal is not torn. In over 90 percent of leaks the cause is old seam sealer and/or silicone that has dried and cracked allowing water to enter the RV. Whether the sealer is on sheet-metal joins or where roof vents have been installed the repair is the same. Caution is advised before you go climbing onto the roof. Check it and make sure that it will support your weight. You may need to obtain a couple of 12 foot ladders so that you can work from the sides of the RV.
First use a putty knife to remove the old sealer. In the case of sheet-metal joins remove the metal molding that covers the join to ensure that all the old sealer is removed. Use a good solvent to clean down to the metal to make sure that when the new sealer is applied it will adhere properly. Never coat the entire roof surface with a sealing material. You only need to coat the seams and areas where the accessories are installed. In most cases, the thinner elastomeric sealers will work the best as they are able to penetrate the smallest gaps in the joins. The thicker materials, usually formulated with alkyd fibers, should only be used when attempting to fill large holes, creases, or bows in the roof. If large gaps are found a self-leveling sealer such as C-10 can be used. This material is able to flow into most cracks and will turn into a solid rubber-like plug within 72 hours. In the case of holes exceeding 3/4 of an inch in diameter you may want to use a small metal plate to cover the affected area. Cut the plate about 1 inch larger then the hole to be covered. Pre-drill the plate to accept small sheet metal screws. Inspect the area where the plate will be placed to make sure that there are not any wires or duct work underneath. Apply lap sealer around the hole and place the plate over it. Put the screws in and apply lap sealer over the screws and around the patch so that all gaps are covered.
Never use silicone or glue type sealers on your roof. When you install new roof vents, holding tanks vents or other accessories make sure to use a good self-leveling lap sealer designed for metal use over the screw heads and around the seams.
A problem that can occur in all roofs is the gasket under the air conditioning system. A large firm foam rubber seal is used to provide water-tight integrity, cushion the air conditioning system and ensure that the seal is maintained even with an uneven roof. This gasket should be changed once a year – yeah, I said once a year – and the roof area around the unit inspected to check for leaks, level and sagging.
Fiberglass roofs are long lasting and durable. Leaks are normally found at points where roof sections join if the roof is not one solid piece. The areas around the vents and other accessories also need to be checked. In most cases, fiberglass roofs are a cap that extends over the roof supports and are not of the walk-on type and to do so can cause severe cracking. Sealing laps, joins and accessories use the same procedures as used on the metal roofs. Large holes can be corrected by placing a patch similar to the ones for a metal roof, or by using fiberglass matting and epoxy. If you’re not absolutely sure how to do a large fiberglass repair it’s best to leave it to a professional. Be very careful when working on a fiberglass roof as they can be very slippery.
Rubber roofs are designed to provide us with a watertight seal that can withstand severe conditions for years of service. Most rubber roofs are of the walk-on variety because the EPDM material is applied as a continuous membrane over a solid backing such as 3/8 or 1/2 inch plywood laid over rafters that provide strength to the roof assembly. Unlike metal and fiberglass, a rubber (EPDM) roof needs some preventive maintenance to keep it clean and prevent possible flaking or streaking of the material down the sides of the RV. To clean EPDM material first rinse the roof with a garden hose using lots of water. Be VERY careful ! Rubber roofs are slippery when wet and falling is a real possibility. Next mix borax, spic-n-span or a similar mild detergent in a bucket of water. Using a stiff bristle brush scrub the roof completely and rinse with plenty of water. Continue to wash until the roof is a uniform white. You will also need to wash the RV after you finish the roof because the surface crud from the roof will be on the sides of the RV and can stain some sidewalls. While you’re washing the roof inspect it for holes, tears or separations in the rubber material. Normally there is no need for a rubber roof sealer. If a sealer is needed, use one recommended by the EPDM material manufactures such as Dicor or 303 brand rubber preservative. Never use a product containing petroleum distillates or citric-based solvents on your rubber roof as these can do permanent damage to the material.
Pinholes, cracks or small open areas will develop around roof openings used for vents and accessories as time goes by. Inspect these areas carefully to determine what type of repair is needed. For holes 1/2 an inch or smaller EPDM lap sealer will do the job. Clean all the dirt from the area to be sealed and apply the sealer. Make sure that sealer adheres to both the EPDM roof material and the accessories being sealed.
If the roof material has holes or tears they can be patched easily using lap sealer and patch kits designed for EPDM rubber which can be purchased from your local RV store. If the rip or hole does not extend into a roof vent or other accessory opening in the roof a patch pre-coated with adhesive can be used. Thoroughly clean and dry the area around the hole. Put on rubber gloves and remove the backing paper from the patch and press it into position. Seal the edges with EPDM type lap sealer using a 5/16 inch bead around the edges of the patch. A trick is to moisten a finger and smooth the bead so that it provides a more secure repair. A smoothing tool can be used if preferred. Repairs to rips or holes up to 3 foot in diameter can be done using these patching techniques and materials available in your RV store.
If the rubber material becomes loose from the backing plywood you may have a problem. This can happen when the material is hot and then being walked. This breaks the glue bond between the plywood and EDPM material. Small areas of 5 inches or less can be ignored but larger areas need to be re-attached to the roof. The process is to inject glue under the EPDM material with a small syringe, use a roller to smooth and spread the glue under the material and then apply pressure to the rubber until the glue sets. To complete the job you must patch the small holes made by the syringe. This job is best left to technicians familiar with the process. In severe cases the rubber may need to be replaced. To do this all the vents, antennas, air conditioners and any other accessories mounted in the roof are removed. The molding is removed around the entire roof where the rubber is lapped into the sidewalls and end-caps. Next the old rubber is removed from the plywood backing. This is not quite as easy as it sounds as the rubber will tear and shred in places and the wood will peel up in others where the glue is still active. The plywood must be smooth before applying the new piece of rubber, this may entail applying wood putty to the plywood backing and sanding it down or replacing sections of plywood. Again, this is a job best left to technicians trained to do the work.
Yep, roofs can be a problem for RV owners. They take some maintenance and inspections, are awkward to get to and are subject to all sorts of stresses and problems, but consider what a RV would be like without them, after all; ya don’t want to see the stars above you through the roof !!
Later – –
The Old Ranger