Painting Steel-Framed Windows and French Doors in Toorak's Interwar Homes

Toorak, Armadale and Kooyong are full of homes from the 1920s and 30s, and a great many of them still carry their original steel-framed windows and French doors. Slender steel sections, small panes, side-hung casements with brass stays, and runs of glazed doors opening onto a terrace were part of what made those houses feel modern when they were built. Ninety years on they are one of the most valued features of an interwar home, and one of the most neglected. Paint flakes off the sash, rust blooms along the bottom rail, the casements stick, and the owner starts getting quotes to replace them. In most cases that is not necessary. Steel windows can be restored and repainted, and done properly they will outlast another generation of paint.

Why steel windows fail

Steel rusts the moment water reaches it, and on a window there are three places where it always does. The bottom rail of each casement, where condensation runs down the inside of the glass and sits against the steel. The joint between the frame and the surrounding render or brick, where the original mastic has long since dried out and let water track behind. And the glazing line, where putty has shrunk and cracked and water gets between the glass and the steel.

Once rust starts under paint it lifts the film from behind, which is why a steel window that looked fine last year can suddenly shed paint in sheets. Rust also expands, so a badly affected rail will push on the glass and crack it, or jam the casement in its frame. The paint is not really the problem; it is the symptom of water getting to the steel.

What proper preparation involves

A steel window repaint is mostly rust treatment. All loose and flaking paint comes off, and any rust is taken back to bright, sound metal with wire brushes, scrapers and abrasive pads rather than painted over. Where rust has pitted the steel, the pits are cleaned out and a rust converter or treatment is applied so nothing is left active under the new coating. This is slow hand work on the small sections and corners of a multi-pane window, and it is the part a cheap quote leaves out.

Old glazing putty that has cracked or pulled away is raked out and replaced, because new paint over failed putty just hides the gap where water is getting in. Loose panes are re-bedded. The joint between the frame and the wall is cleaned out and resealed with a flexible exterior sealant so water stops tracking in behind the frame.

Only then does the primer go on, and it has to be a proper rust-inhibiting metal primer applied to clean, dry steel. That primer is the most important coat on the whole window. Over it go two topcoats of a quality exterior enamel, kept thin on the meeting edges so the casements still close.

Lead paint on original frames

Most steel windows in these homes have been painted many times since the 1920s, and the early layers almost certainly contain lead. Taking those layers back with a power sander or a heat gun is exactly how lead dust ends up through the house and the garden. We prepare original frames with containment, hand methods and proper clean-up, in line with lead-safe practice, which is slower than dry sanding and the reason the preparation hours on these windows are what they are.

Keeping the windows working

A steel casement that has been painted shut, or that drags on its frame, is almost always the result of paint build-up on the meeting edges and the hinges rather than anything structural. Part of a proper repaint is taking those edges back so the sash sits where it was designed to, cleaning and lubricating the hinges and stays, and making sure every casement opens and closes freely before the final coat goes on. The windows are left open to cure rather than shut while the paint is soft.

Where a casement has twisted or a hinge has rusted through, that is a repair for a steel window specialist rather than a painter, and we will tell you so rather than paint around it.

Inside and out

Steel frames are painted on both faces, and the inside face matters more than people expect, because that is where condensation does its work through a Melbourne winter. Inside, the same rust treatment and priming applies, finished in a colour that works with the room; on these homes the frames are often picked out in a darker colour, or in white against a coloured wall. This usually sits within an interior painting job rather than standing alone, so the joinery, architraves and sills are done at the same time.

Colour

Original steel windows were commonly finished in dark colours, and a deep green, a near-black or a dark bronze still suits most interwar facades. Black frames also suit the current taste for contrast against pale render. White frames read well on a lighter, Mediterranean-style house of the period. Whatever the colour, keep the frames consistent across the whole facade and match the French doors to the windows rather than treating them separately.

When to act

The time to repaint steel windows is when the paint first starts to chalk or craze, not when rust is visible, because at that point the steel is still sound and the job is straightforward. Once pitting has set in the preparation hours climb quickly, and once a rail has rusted through the window needs steelwork before it can be painted at all. If your frames are starting to let go, it is worth having them looked at before the next winter.

Steel window work is usually scheduled as part of a full exterior house painting job or a heritage and period-home repaint, where the access and the lead-safe preparation are already set up. We are happy to assess the frames during the free on-site inspection and tell you plainly which ones need paint and which need a specialist.