How to Repair the Fiberglass Roof on an RV

Set a ladder alongside the sidewall of the RV and climb up on the ceiling with a plywood plank. Lay that plywood out in the area you intend to work and stand on it. This will spread out your weight and prevent you from further damaging the roof of the RV.

Inspect both the roof's surface and all of its seams. Barring a hole, if there is a leak in your roof it is because the caulking in the seams around the openings for skylights and/or the air conditioner, or between the roof and the RV's walls, has worn out.

Repair damaged seams with a sealing tape, such as EternaBond. Peel the protective film off the adhesive underside of the tape and apply the tape to the seam in sections of a just a few inches to up to a foot at a time, to guarantee a smooth application. Cut the tape off with scissors at the end of the seam.

Determine how much bad, de-laminated fiberglass you need to cut away from around a hole by thumping it with a hammer, knife or screwdriver handle. Good fiberglass should have a sharp, solid thump. Bad fiberglass has a dull thump, and that needs to be cut away.

Saw away the raggedy fiberglass around the edges of the hole, plus any material that you determined was de-laminated.

Brush a de-waxing solvent to the area surrounding the hole. Permit this to have its effect as directed by the manufacturer, and then wipe it away.

Sand the perimeter of the hole with a power sander using rough-grit sandpaper so that it has a convex surface. Then sand the area immediately around the hole out to about 1 to 2 inches to create a rough surface. These two actions will greatly improve the bond between your fiberglass patch and the roof.

Climb off the roof, go inside the RV and pull off the ceiling panel that is directly underneath the hole in the roof. There should be a plywood panel above that. Unscrew it or pry it out with a crowbar as appropriate.

Wax a piece of plastic large enough to cover the hole and fasten it onto the hole with duct tape. This will create a backing for your patch that you can later remove. Return to the RV's roof.

Measure and cut a fiberglass patch sized to fit the hole plus the rough area that was sanded up in Step 7. Set the patch into place and brush on the patching resin and the hardener. Allow several hours for that to harden, and then continue applying more fiberglass patches, laminating the hole until the patch is level with the roof.

Go back inside the RV and pull the backing away once the last layer of laminate has been placed and allowed to dry. Re-install the plywood panel and the ceiling panel.