Can electric blinds be added later?
Usually yes, on a manufactured roof window, because the blind is a catalogue accessory that clips into brackets already built into the sash and orders against the code stamped on it. The two things that decide how straightforward it is are whether the plaster of the internal reveal has been brought too close to the frame, and where the power is going to come from. Both are settled cheaply before the plasterer arrives and awkwardly afterwards. On a made-to-size flat roof rooflight or a lantern the answer is more qualified, because those blinds are part of the frame rather than an accessory hung on it. The blind types themselves are set out on the roof window blinds page, and the operating side sits under electric rooflight installation.
The plaster line is what decides how easy this is
Every manufactured roof window has a recess at the head and side channels moulded into the sash, and a blind is designed to occupy that recess. If the reveal has been plastered so the finish stops on the outer edge of the frame, everything is available and a blind clips in with a screwdriver in ten minutes.
If the plasterboard has been run past the frame, or a timber lining has been fitted tight over the top rail to make the reveal look neat, the head brackets are buried. Getting a blind in then means cutting the lining back, which is a plastering and decorating job in a finished room. This is the single reason to say at survey that a blind might follow later, because the reveal is then detailed to leave the recess clear and it costs nothing.
The window code is the whole order
Blinds are not measured. Every roof window carries a code on a plate inside the sash, visible when the window is opened, giving the manufacturer, the model generation and the size. That code produces exactly one blind size, and an accessory ordered against it fits without adjustment.
Photograph the plate rather than transcribing it. The codes run to several characters, the model generation letter matters as much as the size digits, and a blind for an earlier generation of the same nominal size will not always land on the same brackets. Where the plate has been painted over or the unit is old enough that the plate has gone, the frame profile and a few measurements will usually identify it, but it is guesswork by comparison.
Where the power comes from, added afterwards
An electric blind motor is small, commonly drawing under half an amp at 24V, and it can be fed three ways. Mains, through the same transformer serving the opener, which is the tidiest arrangement where a supply already exists. Solar, from a photovoltaic strip on the head of the blind with a rechargeable cell behind it. Or battery, from a pack in the blind headrail.
Retrofitting to a window that already has an electric opener is the easy version, because a supply and a control board are already at the head of the frame and the blind is added as another device on the system. Retrofitting to a manual window means one of the other two, and in practice solar is what most people choose, because the alternative is a visible cable running down a finished reveal.
Solar blinds, and the light the head of the frame actually gets
A solar blind carries its panel on the top of the headrail, inside the room, so it charges from daylight coming through the glass. That works well on a south or west facing slope, and it works adequately on an east facing one. On a north facing slope in a Gloucestershire winter it is the weakest link in the specification.
Two things make it worse and are worth checking before ordering. A slope shaded by a taller neighbour, a mature tree or a Cheltenham parapet gets less than the compass direction suggests. And a blackout blind that spends the winter closed shades its own panel, so the more you use it the less it charges. Where a solar unit is being fitted on a north slope, a removable panel that can be charged from a socket for a few hours periodically is the sensible fallback, and that is a product choice made at order.
Side channels, blackout and the millimetres at the edge
A plain roller blind runs on two cords and leaves a gap of a few millimetres down each side. In a sitting room that is unnoticeable. In a bedroom on a west facing slope in June it is a bright line across the ceiling at half past nine in the evening.
Blackout performance comes from side channels: aluminium sections that screw into the sash and capture the fabric edge, along with a fabric that is genuinely opaque rather than merely dark. Channels can be added at the same time as a retrofit blind, and they fix into the same moulded positions, so this is not a decision that has to be taken up front. What does have to be right is the reveal clearance again, because a channelled blind needs a little more depth at the sides than a plain roller.
Retrofitting to a lantern or a kerb mounted flat roof unit
Here the answer changes. On a roof lantern, blinds run in channels fixed to the rafter bars between each glazed pane, and the cabling for a powered version is designed to run inside those bars. Adding them a year later means surface fixing channels to the internal face of the bars and finding a route for cable that was never allowed for, which is achievable but visibly different from the integrated version.
On a made-to-size flat roof rooflight, the frame is usually too slim to hide a blind at all and the shading is more often specified as a coating in the glass. Where a blind is wanted afterwards, it hangs below the unit on its own frame in the ceiling opening rather than inside the rooflight. That works, and it is worth seeing an example before committing. The lantern position is covered on the lantern blinds page.
Older units, changed generations and the honest answer
Manufacturers revise their frame profiles every decade or so, and accessory ranges follow the current generation. On a window fitted in the 1990s the brackets may not exist, the recess may be a different depth, and the blind range for that generation may have been discontinued.
Two routes remain. Independent suppliers make blinds to fit older profiles, ordered by measurement rather than by code, and they are generally manual or battery operated. Or, where the unit is old enough that the gaskets and the glass are also near the end of their service life, the better answer is a new unit with the blind specified as part of it. That gets a current sealed unit, a matching accessory and one visit rather than two, and it is often less work overall than making an obsolete accessory fit.
Doing it while the scaffold is up, or waiting
There is a real advantage to ordering the blind with the window even if the room is not finished. The accessory arrives with the unit, the reveal is detailed around it, the wiring is done at first fix, and the commissioning visit sets the opener and the blind together. Nothing is opened twice.
Waiting is a perfectly reasonable decision, especially where the room is not yet decorated and nobody has lived through a summer in it to know how much shading it needs. Waiting well means leaving three things in place: the plaster stopped clear of the recess, a spare core or a cable capped off at the head of the frame, and the window code photographed and kept with the completion paperwork. With those three, adding the blind later is genuinely an afternoon.
What to leave in place now if the blind comes later
The checklist is short and all of it is free at the right moment. Keep the reveal clear of the head recess and the side channel positions. Run a cable to the head of the frame and leave it coiled and capped in an accessible position, even if nothing is connected to it. Note the transformer location and its spare capacity in the handover pack. Photograph the plate.
Those notes go into the paperwork that follows the job, along with the actuator model and the sensor position. A year later, when the room turns out to be brighter in July than anybody expected, the whole specification for the blind is already written down. The rest of the handover documentation is described on the roof window installation page.
Next on this subject.
- Question Can rooflights be opened electrically? Yes. Almost every category of glazed unit that goes into a roof is available with a motor in it, and…
- Question How much does an electric rooflight cost? No figure is published on this site for an electrically operated rooflight, and the reason is that the motor is…
- Question Do electric rooflights need an electrician? A mains powered rooflight does. A solar one does not, because nothing in it is connected to the house supply…
- Question Can you convert a manual rooflight to electric? Often yes, and the answer is decided by the model rather than by how much effort anybody is willing to…