RV Doctor: How to care for a metal RV roof

Dear RV Doctor,
I read a lot of articles on how to maintain rubber roofs, but I do not find anything about what needs to be done to maintain a metal roof. What are the things that need to be done to maintain a metal roof? –Joe Wilson

Dear Joe,
Many believe it is easier to maintain a metal roof, though those same people extol the benefits and ease of EPDM rubber also. There must first be an understanding of how the metal roof is constructed.

Earlier and lower priced RVs often had a soft roof composed of batts of fiberglass insulation positioned between wood rafters and covered simply by a continuous length of rolled roofing metal typically made of aluminum and having seams every few feet. This was the most common method of roof construction, adopted from the early mobile home industry. The drawback to this method is that you could not safely walk on or otherwise use the roof area.

Damage to the roof was common especially when a technician walked between the rafters thereby stretching the aluminum at its seams or possibly even puncturing or tearing the soft aluminum causing leaks. Installing components such as TV antennas, roof racks or storage pods was also difficult at best.

When working on a soft roof it is always necessary to use wide walking boards long enough to straddle at least three different rafters at the same time in order to distribute your weight enough so as not to damage the seams while working up there. Then someone got the bright idea to add a layer of plywood across the wooden rafters before rolling out the roofing material; the hard roof was born.

I’m not sure who the first manufacturer was that utilized the hard roof but all owners and repair persons since truly owe a debt of gratitude to them. Though the roofing material was basically the same, the plywood substrate now made it easier and safer to walk on the roof, install components and perform the necessary maintenance. Also adopted from the mobile home industry was the basic color of the roof. At first, the aluminum was simply aluminum-colored or silver. It was cheaper to manufacturer, but not as adept at reflecting the sun’s rays as a white roof.

So, many owners completely covered their aluminum roofs with a reflective, white coating. Then producers actually manufactured the roofing rolls in white which became a valid selling point for dealers. The RV roof has seen many innovations over the years including steel and aluminum framing members, Styrofoam insulation, vacuum-bonded, one-piece laminated roof sections, etc. But the aluminum roof still lives on through all the changes and there are many older coaches out there with impeccably maintained metal roofs that have never leaked.

THE SECRET? Frequent inspections and yearly maintenance. Many rolled roofs are made with interlocking sections using cleats or special seams that allow many sections to be joined and then rolled out in seemingly one piece. Other roofs are just simply one piece of aluminum. But remember, any component attached to the roof; 14-inch vents, sewer caps, refrigerator vent, TV antenna, air conditioner, etc., must also be properly sealed. Any attaching screw in or on the roof is a potential leak waiting to happen. All it takes is time and lack of attention and virtually every roof will, at some point, begin to leak moisture.

And realize there is a difference between roof coating and a roof sealant. The coating, remember, was used to effectively insulate the interior by reflecting the sun’s rays. Roof coating is not a viable, stand-alone roof sealant. Moisture can still enter an opening that may be coated and not sealed.

Here’s what I recommend as soon as you take the RV out of storage. First, carefully clean the roof area completely. Wash all dirt and debris from the entire roof. Take care, wet roofs are quite slippery! Next, carefully inspect each seam, front and rear caps and around each component on the roof. If there are any visible signs of cracking in a seam or around any screw head, etc., apply a sealant to plug the opening. Tube silicone is effective in some of these instances. A coating can then be applied over the sealant. I recommend using white coating to aid in reflection.

If, on a soft roof, a seam has cracked opened over a considerable distance, use a piece of fabric webbing along with the sealant. Apply a layer of the sealant, then embed the fabric webbing into this layer. Finally, add another layer of sealant to smooth out the webbing. Apply enough so that it fully covers it. Be sure to feather the edges away from the fabric. The best scenario is to have the sealant and coating remain flexible as the roof expands and contracts with the weather.

By keeping the roof clean and immediately making repairs when something is found amiss, a metal roof should last many years

Gary Bunzer, The RV Doctor is the author of technical articles, troubleshooting tips, installation guides and owner’s manuals for RV owners, suppliers and manufacturers. He is the host of RV Roadtrips, the DIY Network cable television show. He is one of the RV industry’s most sought after speakers and the host of the popular DVD, Do It Yourself RV Care.