Can you paint a garage door, and how do you make it last?

Is painting a garage door worth it? Yes, once the factory finish has faded

Painting a garage door is worth it when the factory finish has gone dull but the door still runs well. B&D says it's normal for a door's surface to fade in colour or lose gloss over time. A tired door isn't always a faulty one.

Before you buy paint, check these four things:

• The warranty. If the door or its steel is still covered, painting can end that cover. More on this below.
• The surface. Colorbond, galvanised steel, bare steel and timber each get different prep.
• The finish. BlueScope says prepping Colorbond in a Matt finish alters the surface, so it recommends a test area first.
• How close you are to the surf. Salt changes the primer you need and how often you wash.

A repainted door won't wear quite like the factory coat. BlueScope says areas painted with air-drying paint may weather at a different rate and vary in appearance over time. That's a good reason to paint the whole door in one go rather than patch it. BlueScope doesn't recommend touch-up paint for scratches on Colorbond either.

Roller, sectional or tilt: the prep follows the door's surface

The shape of the door matters less than what it's made of. Work out the surface first, then follow the maker's prep for it.

A roller door is the odd one out, because its steel curtain coils up every time the door opens. Dulux says Weathershield is made with MaxiFlex technology to expand and contract with the surface, but it doesn't say that covers a coiling curtain. Ask the paint maker before you start. Dulux's advice line is 13 25 25.

Does painting a garage door void the warranty? It can, on the steel and on the door

Yes, painting a garage door can void its warranty. BlueScope says overpainting Colorbond, Zincalume or zinc-coated steel voids any warranty BlueScope issued. That's the warranty on the steel, separate from the door maker's.

Door makers set their own terms. B&D's door warranty excludes damage caused by a surface coating B&D didn't apply. It also excludes damage from prolonged exposure to marine environments, including any installation within 1 km of them. And it excludes damage from a door going without regular washing by rain. B&D gives an eave, canopy, patio, carport or verandah reaching more than 600mm from the wall as an example of what keeps rain off a door.

Other brands may word their warranties differently, so check which brand your door is and read that maker's terms before the first coat goes on.

Paint guarantees have conditions too. Dulux says its Weathershield guarantee doesn't apply where non-Dulux coatings go under or over it. BlueScope recommends not mixing paints from different suppliers, like a primer from one and a topcoat from another. Keep the primer and topcoat from one maker.

How to prep a steel garage door: wash, scuff only newer steel, prime bare spots

For Colorbond that's had more than a year of weather, BlueScope's overpainting bulletin says a uniformly weathered surface should give the paint adequate adhesion. So the prep is a household detergent wash, a rinse with fresh water and time to dry. No scuffing. For Colorbond under about a year old, follow BlueScope's steps below. The last step, priming bare spots, applies at any age:

1. Wash. Use household detergent and water with a mop or a soft nylon broom. Rinse with fresh water and let it dry.
2. Scuff (newer steel only). Lightly roughen the surface with kitchen scourer pads so the paint can grip. Not steel wool. BlueScope says steel wool leaves swarf, tiny bits of metal that can damage and stain the steel.
3. Wash again. Detergent, rinse, dry.
4. Prime any bare spots. For bare, uncoated steel, Dulux says remove all rust by scraping, sanding or wire brushing, then apply two coats of Dulux Precision All Metal Primer. For rust on the coated steel itself, call the paint maker's advice line first.

Steel-Line, a garage door maker, says you can move the door up and down while you prep so you can reach every spot. It also suggests taping over the handles and trims before you paint.

If there's more than a spot or two of rust, read how to repaint rusted metal for the full method. Not sure whether the rest of the door needs primer? See do you need primer.

What paint to use on a garage door: a water-based exterior paint from one maker

Use a water-based exterior paint made for metal, with a primer from the same maker. BlueScope says water-based acrylic is generally the most suitable paint type for overpainting its coated steel. Dulux lists Colorbond, Zincalume, galvanised iron and steel among the surfaces for its Weathershield exterior range. Taubmans says its All Weather exterior paint suits galvanised iron and steel too.

Sheen is the next choice. Dulux says Gloss suits smooth, well-prepared features like doors, but gloss can highlight surface imperfections. It says Semi Gloss gives a smoother, moderately reflective, easy-to-clean finish suited to trims and detailed surfaces. Steel-Line suggests semi-gloss for garage doors because it's low-maintenance.

So a ribbed roller door or a panel with a few dents will show less in semi gloss. A smooth, flat door in good shape can carry full gloss.

For the colour itself, see choosing exterior house colours. For how the main paint types differ, see types of house paint.

Salt air on the Sunshine Coast: wash the door every six months and prime for the sea

BlueScope's salt marine bulletin lists Sunshine Coast beaches as an example of its surf class, meaning areas exposed to breaking surf and ocean spray. BlueScope calls this a guide only. It says prevailing winds, shelter, height above the water and unwashed areas can all change how hard the salt bites.

A garage door is often one of those unwashed spots. Colorbond names garage doors among the areas rain doesn't regularly wash, and says they should be hosed down at least every six months, and more often in coastal areas.

• Prime for the sea. Within 1km of the sea, Dulux says galvanised and Zincalume steel get one coat of All Metal Primer before Weathershield.
• Go heavier where it's worse. In more corrosive salty spots, BlueScope says you may need a paint system with better corrosion resistance, like one with a zinc-rich primer.
• Keep washing after you paint. Dulux recommends washing Weathershield every 6 months in coastal areas and every year in sheltered or inland ones.
• Wash gently. Colorbond says to use mild soap and a soft cloth or soft nylon brush, no abrasive scourers or steel wool, and rinse with fresh water straight after.

For the walls around the door, see the best exterior paint for coastal homes and how long exterior paint lasts.

Brush, roller or spray: a short-nap roller on flat faces, a brush in the grooves

A brush and a short-nap roller together suit most garage doors. For Weathershield Gloss, Dulux recommends a high quality synthetic brush and a short nap synthetic roller, 4 to 6mm. Spraying works too. Dulux gives a 15 to 17 thou tip for airless spray. Here's the order:

1. Pick the day. Dulux says it must stay above 5°C while the paint goes on and dries, and rain or overnight dew on wet paint can damage it.
2. Stay out of the sun. Dulux says to paint the shady side in the hottest part of the day. Steel-Line warns that on a very hot day the door may expand, making it hard for paint to stick.
3. Keep a wet edge. Dulux says to work from an unpainted area into the wet paint to minimise brush marks. Do one panel or section at a time.
4. Wait before the second coat. Weathershield Gloss is touch dry in 20 minutes and ready to recoat in 2 hours, based on 25° and 50% humidity.
5. Finish the whole door. BlueScope says air-drying paint can weather differently to the factory finish beside it, so paint the entire door rather than patches of it.

Springs, cables and the opener are a job for a garage door technician

Painting a garage door is surface work only. Don't adjust the springs, cables, drum, tracks or opener to make the door easier to reach or paint.

Stop at the surface. If the door is hard to lift, sags, or the opener struggles, book a garage door technician before anyone paints it.

Getting the garage door painted with the house

If the house is due for a repaint, do the garage door at the same time so both coats age together. Ask for the door on your exterior quote.

To get a feel for the numbers, see exterior house painting cost, or read the full guide to painting a house exterior. We've painted Sunshine Coast homes since 1985 and hold QBCC licence 1281728. Our exterior house painters work across the coast, including house painters in Dicky Beach. See every suburb we cover.