By Roger Danforth If you do much RV maintenance or repair, chances are good you’ve encountered “putty tape.” This sticky material is a regular performer between windows and walls, roof vents and roofs, and a host of other places where a gasket-like substance is needed to help seal out moisture. Any time you install trim metal, a new roof access ladder, or practically anywhere else you penetrate the outside surface of your rig, you’ll need this gunk-on-a-roll.
For our purposes, there are two types of “putty tape” in play. Regular putty tape is cheap and easy to work with, but dries out over time. Butyl tape is much more expensive (nearly twice the price as the regular), is harder to work with, but doesn’t have the nasty way of drying out. Butyl tape is the only putty tape recommended for use in direct contact with EPDM (rubber) roofing material, as the regular tape oozes petroleum products which can damage EPDM. You can typically find both types at RV supply stores, glass shops, and, of course, on Amazon.
How do you decide which to use? When working with EPDM, it’s a no-brainer. In other areas, the ease of working with the cheap stuff is a temptation. You can simply score the regular stuff, bend it over the score and break it off. The butyl resists this, and usually requires a knife or shears to cut. When reinstalling windows (after the original putty tape dries out and leaks), we always use butyl tape – popping, cleaning up, and reinstalling RV windows is a real time-consumer!
A few tips with either type of tape:
• In warm or hot weather the tape may tend to stick to the backing material. Stick the roll in the refrigerator and chill it. That will make it easier to peel the tape off the roll and the backing paper off the tape.
• Whenever possible, apply the tape to the object, not to the rig. Example: Putty tape the flanges of a roof vent, working the tape down firmly on the flanges before removing the backing paper. Makes the job a whole lot easier, both in terms of eliminating waste, properly locating the tape itself, and getting the backing paper off without a big mess.
• If you’re not sure if the tape is thick enough for the job at hand – particularly true when reinstalling windows on a metal-sided RV – add another layer (or more), screw down the object, and trim the excess goop off. When working with “peaks and valleys” in metal siding, this is the time to apply the tape to the RV – fill the “valleys” piece-by-piece with short strips of tape. Then cover the whole area (right over the top of the short strips) with one large piece.
• A plastic putty knife will usually not scratch fiberglass or aluminum siding while doing such trimming. One old technician says he takes a plastic knife (“Check out the pic-a-nic basket, BooBoo“), files off the serrations, and uses that as the tool of choice for working with the stuff.