Do roof windows need servicing?

What the makers actually ask of an owner

Every manufacturer publishes a maintenance sheet, and every one of them says the same four things in a different order. Clean the pane. Keep the drainage clear. Wash or renew the air filter. Lubricate the moving parts once a year. VELUX, Fakro, Keylite and Roto all print a version of that list, and it fits on one side of A4 because there is genuinely not much to it.

The one item people miss is the drainage. A roof window frame is not a solid box. It carries small channels and weep openings that take water which has run past the outer gasket and return it to the outside of the flashing. Those channels are open to the weather, so they collect moss, pine needles, roof grit and the fine black dust that comes off asphalt shingles and old felt. Blocked, they hold water against the timber at the bottom corners, which is where roof window frames rot first.

The yearly routine, in the order that makes sense

Open the window fully and rotate it if it is a centre-pivot, so the outer face comes inboard and you are working from the room. That is the whole reason the mechanism exists.

• Wash the outer pane with warm water and a little washing-up liquid, then a squeegee. No solvent, no scouring pad, no pressure washer.
• Run a soft brush along the bottom of the frame where the sash meets it, then flush the channels with a jug of clean water and watch it appear outside.
• Pull the ventilation filter out of the top flap, wash it, let it dry, put it back.
• Wipe the gasket with a damp cloth and nothing else, then run a finger along it looking for splits.
• Put one drop of light machine oil on each hinge pin and each friction pad, then work the sash five or six times.
• Close it and check the sash pulls in evenly at both sides.

Late spring is the sensible slot. Winter debris is down, the pollen is finished, and any timber work you decide to do has the summer to dry.

The gasket, which almost nobody inspects

The perimeter gasket is a soft rubber or EPDM strip that the sash compresses against the frame. It is the weather line. It hardens slowly with ultraviolet light and it takes physical damage from grit dragged along it during cleaning, which is the main argument against wiping it with anything abrasive.

What you are looking for is a strip that still springs back when you press it, sits in its groove along the whole run, and has no splits at the corners. A gasket that has gone flat and shiny at the top edge is at the end of its life. Gaskets are a spare part on every major brand and they can be renewed on the window without touching the roof covering, which is the cheapest intervention available on a roof window and the one most often left too late.

Hinges, friction pads and the sash that will not stay open

A centre-pivot window is held at any angle by friction, not by a catch. Two friction pads bear on the pivot bearings and their pressure is adjustable, usually with a single screw at each side under a plastic cover. When a window starts to drift shut on its own, or needs a shove to move at all, that pressure has gone out of balance rather than anything having broken.

Top-hung units use gas struts or a spring arm instead, and those do wear. A top-hung sash that no longer holds itself up, or that slams the last inch, is telling you the struts are tired. They are a stocked spare part on current models. On a window more than twenty years old they may not be, which becomes part of the argument for a new unit.

Timber frames and the lacquer cycle

The pine-cored units are finished at the factory with a clear water-based lacquer that is good for a long time indoors and less good in a bathroom or a kitchen. Steam, and the run-off from winter condensation on the pane, both attack it at the bottom rail first.

The maintenance interval is condition-led, not calendar-led. When the lacquer looks dull and the timber underneath has gone slightly grey at the lower corners, it wants a light key with fine abrasive paper and two thin coats of a water-based acrylic lacquer. Every three to five years in a normal bedroom, more often over a shower. Polyurethane-faced units skip this entirely, which is the real reason they sell into wet rooms. The difference between timber and polyurethane frames is worth understanding before you buy rather than after.

Motorised and solar units carry two extra jobs

An electric unit adds a chain drive that wants the same drop of oil, and a rain sensor that wants wiping. The sensor is a small pad on the outer frame and it works by conductivity, so a film of dust and salt will make it either lazy or twitchy. A damp cloth twice a year settles it.

Solar units add a battery, and batteries are consumables. Expect somewhere around a decade before the window starts closing more slowly than it did and the panel stops keeping up in December. Battery packs are a stocked spare on current ranges.

What a yearly routine will not achieve

It will not bring back a sealed glazing unit that has misted between the panes, because nothing will. That is covered on the misted glass page, and the answer is new glass or a new window.

It will not extend a flashing that has reached the end of its working life, and it will not correct an installation that was wrong on day one. If water is arriving at the ceiling, no amount of oil and filter washing changes that. Detailing at the perimeter is what keeps a roof window dry: upstand and batten heights, the falls, the laps in the flashing, where the covering terminates against it. Those four are invisible once the job is finished, which is exactly why our workmanship carries a ten-year guarantee.

When servicing stops being the sensible answer

There is a point where an old window is absorbing attention it will never repay. The usual markers are all together: a frame past twenty-five years, spare parts no longer stocked, single glazing or early sealed units, a sash that no longer pulls up square, and timber that has gone soft at a bottom corner. At that stage the money goes further on a new unit into the same opening, which is a half-day job and takes the ceiling and the covering with it. We cover that on replacing an old roof window.

What we do, and what we would rather you did

We are an installation and replacement firm. We are not a maintenance round, and we will say so on the phone rather than sell you a visit you do not need. The routine above is genuinely a homeowner job on any window you can reach and rotate from inside.

Where we are useful is the point at which servicing has stopped answering the problem: a unit that needs new glass, a window that has come to the end of its life, or an opening you want changed. We install and replace VELUX, Fakro, Keylite and Roto units across Oxford and up to twenty five miles by road, we have been doing this for fifteen years, we handle the Building Control notification, and the roof is never left open overnight. You get a range by email and a fixed price after a survey.