How to Repair the Fiberglass Roof on an RV

by Jay Kurz
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Most RV bodies are built mainly from fiberglass, a durable, lightweight material that will not rust like metal. RVs spend long hours on the road, and over time roof damage can occur. This requires a repair as soon as possible to avoid water damage inside the RV. Fiberglass can be restored to its original strength using layers of reinforced fiberglass mat that's saturated with a catalyzed resin. When done properly, a repair will last as long as the surrounding fiberglass.

Step 1

Put on a respirator and safety glasses. Grind directly on the damage with a dye grinder until all the frayed and damaged material is ground smooth, forming a grove in the fiberglass. Gradually taper the walls of the grove to give the repair a maximum amount of surface area to bond to.

Step 2

Clean the surface of the repair area with a rag and acetone. Remove all the dust and any other residue that may be on the surface.

Step 3

Tear the first layer of fiberglass mat so it will fit in the bottom of the grove in the damaged area. Make each following layer 1/2 inch bigger than the last to follow the taper of the grove. Use as many layers as it takes to bring the damage back to its original thickness.

Step 4

Put on rubber gloves and add catalyst to a small bucket of resin, following the recommendations on the containers. Stir the catalyst into the resin thoroughly with a stir stick.

Step 5

Wet out the surface of the grove with the resin mixture, using a 4-inch felt roller. Apply the smallest layer of mat to the grove first and saturate it with resin, using the felt roller. Remove any air bubbles that get trapped under the mat, using an air roller. Repeat this process for each layer until the repair is level with the surrounding fiberglass. Let the repair harden.

Step 6

Sand the surface of the repair smooth using 200-grit sandpaper on a sanding block. Sand the repair until it's level and the edges blend in with the surrounding fiberglass. Clean the surface with a rag and acetone.

Step 7

Add catalyst to a small bucket of gel coat that matches your RV's gel coat, and mix it together with a stir stick. Apply the gel coat to the repair using a felt roller. Let the first coat harden and then add another heavy coat. Let the gel coat harden.

Step 8

Apply a heavy coat of boat wax to the surface of the repair and let it dry. Buff the repair to a shine using a clean rag.

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