Repairing a delaminating exterior panel on a motor home requires some care and precision. You must be careful to avoid damaging the exterior panel, exacerbating the damage already present. Delamination is caused by one of two things. One is that the panel was not properly glued at the factory. If you own a motor home still under warranty that is delaminating, return it to the dealership for a proper repair. The other cause is a water leak that breaks down the glue between the fibreglass panel and the wood underneath.
Remove the trim that surrounds the delaminating panel using the screwdriver. If the delamination is happening near the windshield, it is best to have an motor home repair facility repair the damage to avoid creating a worse problem by removing the weatherstripping from the windshield.
Locate the source of the delamination. It will appear as a small hole or crack between the wood substrate of the motor home and the fibreglass outer skin.
Press on the delaminating panel to determine whether the glue has failed. If the glue has failed, you will be able to press in on the panel. You will not be able to press in a panel that is not delaminating. This is not necessary if the delamination is visible. In this case, it will have a round appearance, like a bubble under the surface.
Cut the delaminated panel away using the utility knife and remove it.
Scrape the glue off of the back of the panel using a scraper.
Scrape the failed glue from the wood substrate of the motor home.
Apply construction adhesive to the wood substrate and the back of the fibreglass panel, particularly around the edges of the delaminated panel. Press the panel against the wood substrate and hold it tightly in place for at least five minutes. This will give the glue time to cure.
Run a short bead of construction adhesive across the top of the delaminating panel where you determined the water leak was occurring. Even though you ran a full bead around the repair area previously, this will doubly ensure that future leaks are prevented. It is not necessary to apply construction adhesive to any other area of the panel once it has been glued in place. Allow the glue to dry according to the glue manufacturer's specifications.
Sand the edges of the delaminated panel once the glue has dried completely until they are smooth and even with the surrounding panels using 400-grit sandpaper.
Paint the visible cut lines with touch-up paint and allow it to dry thoroughly.
Sand the edges of the delaminated panel to flatten the touch-up paint using the 1000-grit sandpaper.
Buff the area of the repair with a rag and automotive polishing compound to remove traces of the repair. Reinstall the surrounding trim.
Avoid attempting to repair areas larger than six square inches. This may indicate a more serious problem than a minor water leak.