Why sash windows need more care than casements
A casement window swings on hinges, so a slightly thick coat on its edge rarely matters. A sash window is different. Each sash runs in a channel between the beads and the frame, and the gap it moves in is narrow. Every layer of paint that creeps into that gap makes the window a little stiffer, and after enough repaints the sashes stop moving at all.
There are also more separate pieces to deal with: the two sashes, the glazing bars, the parting bead between them, the staff beads on the inside, the sill and the box frame. Each has faces that weather, faces that rub and faces that should stay bare. Rushing the job with one colour over everything is the usual reason sash windows end up painted shut.
Preparation before any paint goes on
Work starts by scraping away flaking and loose paint until the edges left behind are firm. Sound old paint can stay, but it is rubbed down so the next coat grips. Splits, open joints and small holes in the timber are filled with an exterior grade filler and sanded flush once dry.
Bare wood needs attention before it is coated. Knots are sealed with knotting solution so resin does not bleed through the new finish, and exposed timber is primed. The glazing putty is checked at the same time. Putty that is cracked or coming away lets water sit against the glass and the bottom rail, so that is noted before painting, and the new paint is taken just onto the glass to seal the joint.
For more on why paint lifts in the first place, our guide to paint peeling from walls and ceilings covers moisture and poor adhesion, and many of the same principles apply to window timber.
Keeping the sashes working
The faces that slide against each other, and the channels the sashes run in, are kept clear of thick paint. The sashes are moved during drying so they do not set fast to the beads, and they are left slightly open where it is safe to do so until the paint has hardened.
If a window is already stiff or stuck from earlier paint, the painted seal can often be cut and the sash eased where the carpentry allows. That might mean freeing a bead or taking back built-up paint from an edge. Some problems, such as broken cords or decayed timber, are a separate repair, so we will say honestly what we can see when we visit rather than promise a fix that the window cannot take.
Inside and outside faces
The inside of a sash window is usually painted along with the room, in the same finish as the other woodwork. Our interior painting page explains how frames, skirting and doors are planned with the walls so everything matches.
The outside face takes the weather, so it needs the more thorough preparation described above. We paint the outside only where it can be reached safely from the ground or a standard ladder. We do not use scaffold or towers, so upper windows that cannot be reached that way are left out of the quote. Front doors, fascias and other outside timber can be added through our exterior painting service.
Timing the outside coats
Exterior coats are planned for dry, mild weather. Timber that is damp from rain or dew will not hold primer properly, and paint applied in cold conditions can stay soft for longer than it should, which is exactly when a sash is most likely to stick. If the forecast turns, outside work is moved rather than forced through, and inside faces can often carry on in the meantime.
Older homes with original sashes
Many older houses around Chorleywood and Rickmansworth still have timber sash windows. Original sashes tend to carry many coats from past decades, and the beads may have been painted in so many times that their edges have softened. Taking the time to clean those edges back gives a crisper finish and helps the window move more freely.
Where a house has a mix of original and later windows, the preparation is matched to each one rather than treating them all the same.
Getting a quote
Count how many sash windows you want painted, note whether it is the inside, the outside or both, and mention any that are stuck or rattle. A visit lets us look at the condition and give a free quote. See the wider painting and decorating service, or contact us or call 07735 852901 Monday to Friday, 8am to 4pm.