A freshly painted garage door significantly improves kerb appeal and provides a protective coating that extends the life of the door surface. The process differs slightly between metal, timber, and GRP doors, but the principle of thorough preparation before painting is universal.

How to Paint a Metal Garage Door

Steel garage doors require preparation that removes any existing rust, loose paint, and contamination before a new coat is applied. Begin by cleaning the door with a degreasing cleaner to remove oil, wax, and dirt. Sand the whole surface with medium-grit abrasive paper (80 to 120 grit) to provide a key for the new paint and to remove loose or flaking existing paint. For any areas of rust, sand back to clean metal and apply a rust-inhibiting primer immediately. Apply a metal primer to the full door surface if the existing paint is being taken back substantially, or use a high-build primer on sound existing paintwork. Allow the primer to dry fully before applying the topcoat.

For the topcoat, use a weather-resistant enamel or a purpose-made metal door paint in a satin or gloss finish. Apply two thin coats rather than one thick coat, allowing full drying time between coats. A foam roller produces a smoother finish than a brush on flat panel sections; a brush is better for edges and detail sections.

How to Paint a Metal Garage Door That Is Peeling

A peeling metal garage door requires more extensive preparation than one in sound condition. Remove all loose and peeling paint using a scraper, wire brush, or angle grinder with a wire cup wheel for large areas. Sand the edges of the remaining sound paint to a feathered edge so they do not show through the new coat. Prime all bare metal areas immediately with a rust-inhibiting primer. Once all primed areas are dry, apply a full coat of primer to the whole door surface before topcoating. Skipping this step results in the new paint peeling again from the same areas within months.

Timber and GRP Doors

Timber doors should be sanded smooth, any cracks filled with exterior wood filler, and the surface primed with an exterior wood primer before applying a compatible topcoat. GRP fibreglass doors require a GRP-compatible primer; standard metal or wood primers do not adhere well to fibreglass and will peel. Check the paint manufacturer's specifications for the appropriate primer for GRP before starting.

Summary

Prepare metal doors by degreasing, sanding, and priming bare or rusted areas before topcoating. For peeling paint, remove all loose material and re-prime the whole surface. Use weather-resistant enamel or metal door paint for the topcoat. Paint timber doors with exterior wood primer; GRP doors with GRP-compatible primer. Paint on dry days between 10 and 25 degrees Celsius for the best result.