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RV Drip Caps (sometimes referred as drip rails) are aluminum metal hoods that can be installed at the top of the windows or doors on your RV to prevent water from running down the exterior and possibly leaking in through the seals or door screens.  

While residential drip caps installed on the roofs or decks of houses are generally made of galvanized steel, these are different configurations.  They are a different shape and are never installed on an RV's roof.  They only cover the area immediately above the door or window.  

Caps are U-shaped with corners that curve around the top corners of the door or window and have a flange (see our article on "What is a flange" if you don't know what that is) with screw holes to attach the drip rail to the RV or park model sidewall.

Manufacturers of RV Drip Caps

RV Part Shop offers this product from two different manufacturers: Grace Manufacturing and Dexter Group.  Each of them calculates the measurement in a different way.

Grace Manufacturing sizes their caps from the inside of one rounded, vertical end to the other.

RV Drip Caps

Dexter Lengths are measured as the overall length of the entire drip cap, including the mounting flange. Generally, you can expect the flange to measure about 1" on each side.

Measuring for the Correct Drip Cap

The first thing to do when you want to do a new installation of these caps is to measure the overall width of the window or door that you want to protect.  Measure to the full outside or the frame or outer trim. Your new cap should be wide enough to cover at least that full width.

Selecting the correct cap is simple for Grace Manufacturing caps. Just purchase the next size up from the width of your window or door.

For Dexter Group caps, add 2-1/2 to 3 inches to your window or door measurement to account for the width of the left and right flange.  You will need to purchase the next largest width of drip cap to fully cover the window or door.

Of course, if you are replacing an existing cap, you can just buy the same size as your original. Just make sure you are aware of the different sizing methods of the two manufacturers when selecting the replacement.

Installing your RV Drip Cap

installation is simple, just make sure you apply putty tape to the underside of the flange before screwing the cap to the side of the RV.  You can use either putty or butyl tape on a sidewall (only butyl tape should be used on rubber roofs.)

Once you have screwed the cap down tightly, carefully scrape all the excess putty tape from around the cap and allow it to dry.  Once that is done, you can ensure you have a good seal by applying a bead of sealant around the top edge of the cap.  We recommend Proflex clear sealant.

Need More Help?

If you have any other questions about drip caps or need help selecting one, contact one of our customer service professionals for assistance.

REGULATORY NOTE: While drip caps, drip rails, drip edges, head flashing, drip cap flashing, and head trim are usually required as part of local building codes, there is no such requirement for RV installations.

Nick is the author of this solution article.

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