Paint Peeling Off Metal Railings or Doors? Why

Short answer

Paint on exterior metal usually fails for one of four reasons: rust that was painted over, galvanized steel painted with the wrong primer, a surface that was not cleaned or roughened, or thin coats on edges and welds. Rust left under paint keeps growing and lifts the paint from underneath, often starting at a scratch or a joint and creeping outward. Galvanized steel is smooth and zinc-coated, and some ordinary paints and primers do not bond to it and peel off in sheets. Old glossy paint that was not scuffed, and dirt, grease or chalk left on the surface, give new paint nothing to grip. Edges, corners and welds hold the thinnest paint and rust first. A lasting repaint means removing loose paint and rust, cleaning and degreasing, a primer made for that metal (rust-inhibiting on steel, compatible with zinc on galvanized), and two finish coats rated for exterior metal, with extra attention on edges and welds.

Roof-level steel framing freshly painted in grey on a FAIME commercial job in Vaughan — Roof metals painted on FAIME’s Vaughan commercial project, part of a scope that also covered railings, metal stairs and dock doors.

Read how the paint is failing

Rust under the paint

Bubbles or blisters with rust inside
Rust spreading out from a scratch, chip or joint
Rust bleeding at welds, bolt heads and the bottom of posts
Orange streaks running down onto the wall or paving below

Paint letting go

Sheets peeling off with bright, clean metal underneath: often galvanized steel with the wrong primer
Flakes lifting off an older glossy coat: the old paint was not scuffed
Peeling where hands and feet wear on railings and treads

Why paint fails on metal

Rust was painted over. Paint does not stop rust that is already there. Moisture reaches it through the thinnest spots, and the rust keeps growing underneath and lifting the paint. This is called rust creep, and it spreads outward from every chip and scratch.
Galvanized steel, wrong primer. Many railings, stairs, posts and door frames are galvanized. New galvanizing is very smooth, and some paints and primers, especially some traditional oil-based types, do not bond well to zinc and can peel off in sheets. Galvanized steel needs cleaning, sometimes light roughening, and a primer made for it.
No surface prep. Dirt, grease, chalky old paint, loose rust, and glossy paint that was not sanded all stop new paint from gripping.
Thin paint on edges, corners and welds. Paint pulls away from sharp edges as it dries, leaving the thinnest film where the metal is most exposed. Rust starts there.
Wrong conditions. Metal gets colder and holds dew longer than the air around it. Painting cold, damp or dewy metal traps moisture under the film. Painting in direct sun on hot metal can make paint skin over too fast.

How to repaint metal so it lasts

Remove loose paint and rust

Scrape, wire-brush and sand back all loose paint and rust. Sound paint can stay if it is scuffed. Heavily rusted or pitted areas take more work, and badly corroded metal may need repair or replacement before painting.

Clean and degrease

Wash off dirt, grease, chalk and sanding dust, and let the metal dry completely.

Prime bare metal the same day

A rust-inhibiting primer on bare steel, or a primer made for galvanized metal on zinc-coated steel. Bare steel starts to flash-rust quickly, so it should not be left unprimed.

Stripe the edges

An extra brushed coat on edges, corners, welds and bolt heads, where the film is thinnest and rust starts first.

Two finish coats for exterior metal

A finish made for exterior metal, applied in two full coats on dry metal in the right temperature range, out of direct sun where possible.

On a commercial building

Railings, stairs, entry doors, dock doors and roof metals are what visitors, tenants and delivery drivers see up close. On a repaint, they are also the details that make a new wall colour look finished. A freshly painted wall next to a rusty railing or a peeling dock-door frame still looks neglected. Metals should be scoped as part of the repaint, not left for later.

Where FAIME fits

Painting exterior metals is a self-performed FAIME scope across Toronto, North York, Scarborough, Vaughan, Richmond Hill, Markham, Mississauga, Brampton and the wider GTA, on houses, storefronts and large commercial buildings.

On our Vaughan commercial envelope project, the metal scope included the roof metals, entry plaza doors and railings, the metal stairs, painted completely black, and the dock doors and the rusted metal edges around them, all as part of the same job as the wall repairs and two-coat repaint, on an occupied building finished in 7–10 working days.

$2M general liability · Active WSIB (Class G5) · 2-year workmanship warranty
Sherwin-Williams, Benjamin Moore and Dulux coatings

Frequently Asked Questions

Why is paint peeling off my metal railing?

Usually one of four things: rust that was painted over and is lifting the paint from underneath, galvanized steel painted with a primer that does not bond to zinc, a surface that was not cleaned and scuffed before painting, or thin paint on edges and welds where rust starts first.

Can I paint over rust on metal?

Not over loose rust. Paint does not stop existing rust, and it keeps growing underneath and lifting the new paint. Remove loose rust and paint back to a sound surface, clean it, and prime bare steel with a rust-inhibiting primer before the finish coats.

Why does paint peel off galvanized steel?

New galvanized steel is smooth and zinc-coated, and some paints and primers, especially some traditional oil-based types, do not bond well to zinc. Galvanized metal needs to be cleaned, sometimes lightly roughened, and primed with a product made for galvanized surfaces.

How often should exterior metal railings be repainted?

It depends on exposure, wear and how well they were prepared and painted. Inspect them each spring and touch up chips and scratches before rust creep starts, especially on treads, handrails, welds and the bottom of posts.

Can dock doors and metal stairs be painted on an occupied commercial building?

Yes, with sequencing. On FAIME’s Vaughan commercial project, the dock doors and their metal edges, entry doors, railings, metal stairs and roof metals were all painted while the tenant stayed open, by protecting, painting and returning each area in turn.

Does FAIME paint exterior metal railings and doors in the GTA?

Yes. Painting exterior metals is a self-performed FAIME scope across Toronto, Vaughan, Richmond Hill, Markham, Mississauga, Brampton and the wider GTA. FAIME is WSIB Active under Class G5, carries $2M general liability and backs its workmanship with a 2-year warranty. Site visits are free.

Paint Peeling Off Metal Railings or Doors? Why It Happens and How to Make It Last