How do you clean a rooflight you cannot reach?
Mostly by choosing a unit that solves it before it goes in. Glass over a stairwell, above a double height kitchen or high on a second floor slope is not cleanable with a cloth from a chair, and the three practical routes are a sash that rotates and locks so the outer face comes inside the room, a water fed pole from ground level, or a self cleaning outer coating that lets weather do the work. Each of them has limits, and the limits are set by the geometry of the building rather than by effort. Which is why the useful moment to answer this is at specification, when the choice between a fixed unit, a centre pivot and a top hung one is still open. General cleaning of a reachable unit is covered on cleaning the outside of a roof window and cleaning and maintaining a rooflight.
What out of reach usually turns out to mean
Three situations account for nearly all of it. The first is a unit over a stairwell or a galleried landing, where there is a floor below but no floor under the glass, so nothing can be stood on. The second is a double height space, common in converted barns around Newent and Hartpury and in modern extensions at Bishops Cleeve. The third is a second floor slope on a three storey house, which includes the Cheltenham townhouses at Montpellier and Lansdown and the terraces that step up the hillside at Chalford.
They are different problems. The first two are internal reach questions with easy external access. The third is the reverse. Working out which one applies decides everything that follows, and it is worth being clear about it before buying anything.
A sash that rotates, which brings the outside in
A centre pivot roof window is hinged across the middle of the frame, and the sash rotates through most of a half turn until the outer face is inside the room and the inner face is pointing at the sky. A barrel bolt at the head holds it in that position, and until that bolt is engaged the sash can swing back, so it is engaged before anything else happens.
That single feature answers the stairwell and the double height problem completely, provided somebody can reach the handle. Both faces of the glass are then cleanable from a step or a small platform on the landing. Most top hung units in the major ranges also rotate to a cleaning position, releasing from the top hinge and pivoting on a second point, which is worth confirming against the specific model rather than assumed. A genuinely fixed unit has no cleaning position at all, which is the trade off for its lower cost and slimmer frame.
Water fed poles, and how far they really go
The tool professional window cleaners use is a telescopic carbon fibre pole feeding purified water to a brush head. The water is deionised, so it dries without leaving mineral marks and no squeegee is needed, and the operator stays on the ground.
Reach is where expectations run ahead of reality. Poles are made to considerable heights, but a long pole is heavy, it flexes, and controlling a brush head at full extension takes real skill. On a roof the geometry works against you as well: glass in a sloping plane sits back from the eaves, so the pole has to travel the height of the wall and then a further distance up the slope, and the angle of attack gets progressively worse the further up the roof the unit sits. A ground floor extension rooflight is comfortable work from a pole. A unit high on a three storey slope frequently is not.
A self cleaning outer pane, and the conditions it needs
Self cleaning glass carries a permanently bonded coating on the outer face which does two things. Ultraviolet light breaks down organic film on the surface, and the coating makes the glass hydrophilic, so rain sheets across it rather than beading and carries the loosened dirt away instead of drying into spots.
It works well, within conditions. It needs daylight, so a unit shaded by a large tree or a neighbouring gable performs less well. It needs rain to arrive on the glass, so a unit under a deep overhang gets less benefit. And it needs pitch: below roughly 15 degrees water does not sheet off properly and dust stays put, which is one of the reasons made to size flat units are set at a minimum of about five degrees and self cleaning is a weaker proposition on them than on a pitched slope. It also does nothing for bird droppings, moss debris, or the inside face. On a unit that genuinely cannot be reached it is worth specifying anyway, because it lengthens the interval between the times somebody has to.
Reaching the handle, before reaching the glass
A rotating sash is only useful if the handle can be operated, and on a unit above a stairwell it often cannot. Two answers exist. A telescopic operating rod hooks into the handle or a dedicated eye on the sash and works from floor level, and it is the cheap answer, though it is awkward at full extension and it needs somewhere to live between uses.
The better answer on a genuinely high unit is an electric opener, which also solves the ventilation problem sitting behind it. A vent nobody can reach is a vent nobody uses, so the unit that gets specified electric is usually the one that most needed opening in the first place. Some powered units drive to a defined cleaning position on a single command. Actuators, controls and rain sensors are covered under electric rooflight installation, and the case for them in this exact situation on electric rooflights out of reach.
Getting at it from outside, and why a roof is not a wall
Cleaning a vertical window from a ladder is routine. Cleaning a rooflight from one is a different proposition, because the ladder has to be footed on a slope or leant against a gutter that was never designed to take it, and the operator ends up reaching sideways across a surface that is slippery when wet and fragile in places.
Where external access is genuinely required, a mobile tower on level ground or a scaffold is the honest answer, and on a slope that means roof ladders and edge protection. That is a proper job with a cost attached, which is precisely the argument for solving it at order stage. On the valley sites at Rodborough and Nailsworth, where there is nowhere flat to stand a tower at all, the specification decision matters more than anywhere else in the county.
The inside face, which people forget until February
Overhead glass in a heated house collects a fine film on the room side from cooking, candles and general household dust, and it shows up as haze when low winter sun comes through it. That film is not condensation and it does not wipe itself away.
On a rotating sash it comes off in the same session as the outer face. On a fixed unit high in a void it is the harder half of the problem, because a pole cannot be used indoors near a stair drop. A long handled microfibre head on a light pole, used from a landing with somebody holding the base of the stair, is the usual practical answer. It is another reason a fixed unit in a stairwell is a decision worth thinking about twice.
What actually lands on the glass in this county
What accumulates decides how often any of this is needed. Under trees, which is most of the Stroud valleys and the wooded Forest of Dean edges, it is leaf tannin and organic film, and that is exactly what a self cleaning coating handles best. On the wolds it is dust off arable fields in late summer. Near the Severn it is a fine silt after a wet winter.
Moss is the one that matters structurally. It grows on the covering rather than the glass, and it washes down onto the head of a unit and sits against the flashing, holding water where the detail wants to shed it. Clearing debris off the head flashing and out of the frame’s drainage channel once a year does more for the unit than cleaning the glass does, and it is worth doing whenever access is arranged for anything else.
Designing the problem out before the order goes in
The pattern is consistent. Where a unit will be out of reach, the specification wants a rotating sash rather than a fixed pane, an electric opener rather than a rod, a self cleaning outer surface, and a laminated inner pane because there is habitable space below it. Together those add modestly at order stage and remove a recurring cost and an access hazard for the life of the roof.
The wrong version of this decision is a fixed unit chosen for its slim frame and its lower price, set high above a stairwell, which then needs a tower every time anybody wants to see through it. That question gets asked at survey, along with how the glass will be reached in fifteen years, and the answer goes in the notes. The whole process is on the skylight and rooflight installation page.
Next on this subject.
- Question Do rooflights need planning permission? Usually not. Putting a rooflight into the roof of a house is normally permitted development, which means the national rules…
- Question Do I need building regulations approval for a rooflight? Yes. Forming a new opening in a roof is notifiable work under the Building Regulations, and it is notifiable whether…
- Question Who notifies building control about a rooflight? In law the duty sits with the person having the work carried out, which means the homeowner, and in practice…
- Question How much does a rooflight cost? There is no single figure, and any site that publishes one is quoting for a job it has not seen.…