How to paint sash windows the right way.

6 min read · Sandwich Painter

Helpful video reference. The video above is "How To Paint A Window" from howtopaintinfo, demonstrating the correct working order on a real sash window, including the areas to leave paint-free described above.

Work from the glazing bars outward

Start with the glazing bars (the thin sections dividing the panes), then the rest of the sash frame, working outward toward the outer edges. This order means any small drips or overruns from the detailed glazing-bar work get covered by the following coats rather than sitting visible on a finished section.

Paint the bottom sash first, both the inside and outside faces, before moving to the top sash. Sashes need to be raised and lowered slightly during painting to reach the full frame, so working bottom-then-top keeps you from repeatedly disturbing wet paint on a section you've already finished.

Never paint the meeting rail or the pulley stiles

The meeting rail (where the top and bottom sash overlap when the window's shut) and the pulley stiles (the vertical channels the sash slides in) are the two areas that must stay paint-free. Painting over them is the single most common reason a freshly painted sash window won't open the following week, the paint effectively glues the moving parts together.

If a previous paint job has already sealed these shut, they need to be carefully cut free with a paint scraper or shave hook before repainting, not just forced open, which can crack the timber.

Prep and paint choice for older frames

Key the surface first with medium-grit sandpaper to remove any existing gloss or sheen, giving the new coat something to grip. Bare or fully stripped timber needs a proper primer and undercoat before the topcoat, skipping this step is a common reason paint fails to adhere and peels within a year or two.

For UK conditions, a flexible, breathable microporous water-based paint lets older timber move with damp and temperature changes without cracking the paint film. Traditional heritage oil-based gloss is also a legitimate choice on genuinely period Victorian or Georgian sashes, durable and authentic to the period, but slower drying and less forgiving of movement than a microporous system.