RV skylights take a lot of abuse. They get hit with tree branches, endure the sun's harsh rays day after day and may even get pounded by hail. RV skylights are made of strong, though not unbreakable, plastic material. Cracks in skylights happen and even worse, sometimes the skylights completely shatter. Replace cracked or broken skylights immediately to prevent water from entering your RV and causing damage. Save a few bucks and replace the skylight yourself, instead of paying a professional to do the job.
Climb up on top of the RV, using the RVs built-in ladder, bringing a measuring tape, pen and paper with you. Measure the length and width of the base of the skylight. Write down the measurements on a piece of paper.
Purchase a new RV skylight at a RV supply store. Use the measurements you wrote down to make sure you buy the correct size. RV manufacturers all use the same sizing guidelines for skylights, which makes purchasing a new one fairly easy. There are only few different sizes available, so it shouldn't be difficult to locate the correct size for your RV.
Look at the skylight while standing inside your RV. Some RV skylights have screws on the interior side of the RV. If yours does, remove the screws using a Phillips-head screwdriver.
Gather up your supplies and place them in a plastic grocery bag. Place the handles of the shopping bag over one of your arms, leaving your hand free so that you can use both hands to climb up the RV ladder.
Scrape off the putty or caulking from around the base of the old skylight using a putty knife. Work gently with the putty knife to avoid damaging the RV roof.
Remove the screws from around the base of the skylight using a Phillips-head screwdriver and pull out the old skylight.
Look to see if there is butyl tape underneath where the skylight flange was. If there is, remove it. Use the putty knife, if necessary, to loosen the butyl tape before pulling it off.
Clean along the edge of the exterior area of the skylight hole, underneath where the skylight flange was, with a rag and isopropyl alcohol.
Place new butyl tape along the edge of the skylight hole, over the pre-drilled screw holes, where the new skylight flange will sit.
Screw on the new skylight, placing the screws inside the pre-drilled holes on the skylight flange through the pre-drilled holes in the RV roof. You may have to use a little force to push the screws through the butyl tape that covers the pre-drilled holes on the roof.
Cut off any butyl tape visible around the edge of the skylight, using a utility knife. Work slowly and only apply slight pressure with the utility knife to avoid damaging the RV roof.
Squeeze the self-leveling butyl rubber caulk around the edges of the base of the skylight to create a seal to prevent water from leaking into the RV. Put on a pair of latex gloves and spray your gloved finger tip with water. Run a moistened, gloved finger gently over the top of the caulking to smooth it out and make it look neat.
Go back inside the RV and replace the screws on the interior side of the skylight if applicable.