Garage Door Paint Peeling or Rust Coming Through? How to Fix It
Most garage door failures start with rust or a surface that was never prepared.
A garage door takes years of sun, rain, frost and knocks, usually across a big, flat panel that shows every flaw. When paint peels or rust bleeds through, the cause is nearly always underneath: rust that was painted over, new galvanised steel that was never prepared, or an old coating that had already lost its grip. Here's how to work out which, and how to repaint a door so the finish lasts.
At a glance
- Rust spots mean bare steel is corroding under the paint: remove it, then prime.
- New, shiny galvanised steel needs special preparation or paint will peel.
- Remove all loose paint, key what remains, clean and let it dry.
- Paint in dry weather, above 10 °C, with no rain due until it has dried.
- Our Garage Door Paint suits metal and composite doors, not timber doors.
Rust coming through the paint
Paint over rust and the rust keeps growing.
Brown spots or streaks, often along the bottom edge, around fixings or where the door has been scratched, mean water has reached bare steel and it is rusting under the paint. Rust expands as it grows, pushing the paint off around it. Painting over it seals the moisture in and the rust carries on.
Wire brush or sand every rusty area back to clean, bright metal and feather the paint edges around it. Wipe off the dust, then prime the bare metal straight away with a metal primer suitable for the door, before it has a chance to flash-rust, and follow the primer with your finishing coats over the whole door.
Peeling off galvanised steel
Fresh zinc coating is too smooth for paint to grip.
Many steel garage doors are galvanised: coated in zinc to protect the steel. New galvanising is very smooth and can carry residues from manufacture, so paint applied straight onto it often looks fine at first and then peels off in sheets. Galvanised surfaces need specific preparation, such as a suitable etching treatment or a primer made for galvanised metal, before painting. Factory-coated doors also need degreasing and keying first. Check what your door is made of and follow its manufacturer’s guidance on repainting.
How to repaint a garage door properly
Sound, clean, keyed, dry, then thin coats.
Scrape off all loose and flaking paint back to a firm edge, deal with any rust as above, and key the remaining sound paint with a fine abrasive until it is evenly dull. Wash the whole door with a detergent solution to remove dirt, traffic film and chalky residue, rinse thoroughly and let it dry completely.
On old doors, take care: many older metal doors and frames were primed with lead-based paint. If paint may contain lead, avoid dry sanding and burning off; use wet abrasive paper or a chemical stripper and collect the debris. Paint on a dry day, above 10 °C, out of strong direct sun, when no rain or dew is expected before the paint has dried. Brush the recesses first, then roll each panel while keeping a wet edge.
Where our paint helps, and where it cannot
Weatherproof and flexible, on correctly prepared metal and composite.
Our Garage Door Paint is a weatherproof, flexible exterior finish made for wide panels, with easier rolling across large areas. It suits metal and composite garage doors that have been correctly prepared and primed where needed. Our exterior paints are flexible, not breathable, so they are not suitable for wooden windows or doors, including timber garage doors. High opacity usually gives solid colour in two coats, though three may be needed. No paint will stop rust that has been painted over, so prepare the metal properly first.
Sample it the way we would
Step 1
Paint your peel-and-sticks
Each £5.99 sample comes with three paintable peel-and-sticks. Give them two coats and let them dry fully.
Step 2
Stick them around the room
Put them on two or three walls, including the wall opposite the window, at eye level and lower down.
Step 3
Live with them for a day or two
Look in the morning, the afternoon and under your evening lamps. Move them around until you are sure.
Your questions, answered
Why is paint peeling off my metal garage door?
Usually rust underneath, untreated galvanised steel or an old coating that has lost its grip. Remove loose paint, treat rust, prepare and prime, then repaint.
Can I paint over rust?
No. Remove the rust back to clean metal, prime it straight away with a suitable metal primer, then paint.
Can I use your paint on a wooden garage door?
No. Our exterior paints are flexible, not breathable, and not suitable for wooden windows or doors.
What weather do I need to paint a garage door?
A dry day above 10 °C, out of strong direct sun, with no rain or dew expected before the paint has dried.