Blinds are the accessory people decide about last and the one that is cheapest to decide about first. Nothing about a blind is impossible to add later. Several things about it are neater, cheaper and better fixed if the decision is made before the linings go on.
What a roof window blind has to do differently
A blind on a vertical window hangs. A blind on a sloping window does not, and that single difference decides the whole product.
On a slope, gravity pulls the fabric away from the glass rather than against it. So a roof window blind runs in side channels that hold the fabric to the sash, and it is guided rather than hanging free.
That means the fixings are into the sash or the frame at specific points, and those points are what the timing argument is about.
Fitted at installation
The blind fixings are made into the frame before the internal linings are formed around it.
- The fixings are concealed by the linings rather than sitting on top of them.
- The reveal can be formed to suit the blind rather than the blind being fitted to whatever reveal exists.
- Any cabling for a powered blind runs while the ceiling is open.
- There is one visit and one lot of mess rather than two.
- The blind and the window are ordered together, so the fit is exact rather than approximate.
Added later
Entirely possible, and the compromises are modest but real.
The fixings go into the sash and frame from inside, so they are visible rather than concealed. A reveal that was plastered tight to the frame may need trimming back. A powered blind now needs a battery or a solar unit rather than a cable, or it needs the ceiling opening.
None of that is a reason not to add a blind later. It is a reason to decide before the linings if you already know you want one.
The types, and what each is for
| Type | Does | Suits |
|---|---|---|
| Blackout | Excludes light almost entirely in side channels | Bedrooms, nurseries, anywhere somebody sleeps |
| Roller | Reduces light and glare, does not exclude | Living space, a study |
| Pleated | Diffuses light, adjustable from either end | Where soft light matters more than exclusion |
| Venetian | Directional control of light | A study or a workspace |
| External awning | Stops solar heat before it reaches the glass | Overheating, rather than glare |
Blackout, and the reason it is the common answer
A roof window faces the sky, and the sky is bright for a great deal longer than most people expect.
In a loft bedroom in June it is light well before four in the morning and still light late in the evening. A vertical window in the same room takes a slice of that; a roof window takes the whole of it, directly overhead.
Which is why blackout is what most loft bedrooms end up with, and why fitting a roller blind first and a blackout second is a mistake people make once.
The side channels are the product
The difference between a blind that blacks out and one that mostly does is the side channels.
Without them, light leaks down both edges of the fabric and the room is dim rather than dark. With them, the fabric is held in a channel that closes that gap, and the exclusion is close to total.
If blackout is the point, the channels are what you are buying. A blackout fabric without them is a dark roller blind.
Heat is a different problem from light
A blind fitted inside the glass stops light after the solar energy has already entered the room. The heat is inside, and the blind is now a warm surface radiating into the space.
It controls glare very well. It controls heat poorly, and it is not a substitute for the right glass.
External awnings work the other way, stopping energy before it reaches the glass, and they are considerably more effective on heat. They are exposed to the weather, they need cleaning, and they change how the roof looks from outside, which is why they are less common on a domestic roof and worth raising where overheating is the actual complaint.
Order the glass for heat, the blind for light
This is the sequence that avoids paying twice.
Specify the glass to deal with solar gain, at the ordering stage, where it cannot be revisited. Then add a blind for glare, privacy after dark and blackout, which can be revisited.
Doing it the other way round means buying a blind to solve an overheating problem it cannot solve, and then still needing the glass.
Manual and powered
The same reach argument as the window itself, and it frequently has a different answer.
A window high in a roof may be operated with a pole perfectly well, and a blind on the same window is fiddlier to work with a pole because it has to be positioned rather than simply opened. Powered blinds are therefore worth considering at heights where a manual window is still fine.
Powered blinds run on mains, battery or solar, with the same trade as the windows: the cable is decided before the ceiling closes, and solar exists precisely because that moment passes.
Privacy after dark
An overhead window is private during the day almost everywhere, which is one of its pleasures, and after dark it is not.
A lit room behind glass is visible from anywhere with a line of sight to the roof, and on rising ground that is more places than people assume. In Hove, Brighton and the villages under the scarp, a rear slope is frequently overlooked from streets or footpaths above.
Where the room is a bedroom or a bathroom, that is worth checking at survey rather than discovering in the first winter.
Dark skies
Inside the South Downs National Park there is a further reason blinds matter, and it is a planning consideration rather than a comfort one.
The Park is an International Dark Sky Reserve, and a large area of glass in a roof with lights on below emits light directly upward in a way a vertical window does not. Blinds are the practical mitigation.
Specifying them with the unit and saying so in the application is one of the things that makes a proposal in the Park easier to support.
Bathrooms and shower rooms
A blind in a wet room needs a fabric that tolerates humidity and does not hold moisture.
Pleated and roller blinds in suitable fabrics are the usual answer, and heavy blackout fabrics are frequently unnecessary in a bathroom because privacy overhead is not an issue and nobody sleeps there.
What matters more is ventilation, which is the window rather than the blind, and a blind should never be fitted in a way that obstructs the trickle vent.
Fitting a blind to somebody else’s window
Blinds are made for specific window ranges and specific size codes, and they are not generic.
Which is why the data plate matters here too. The type and size code identify what will fit, and ordering by measurement rather than by code is how a blind arrives close but not right.
Where a window is old enough that no current blind is made for it, third party and made to measure options exist, and the fit is rarely as neat as a matched product.
What a blind does to the mechanism
Very little, and one thing is worth knowing.
On a centre pivot the blind rotates with the sash, so it stays with the glass when the window is turned for cleaning. On a top hung unit the blind swings out with the sash. Both are designed for it.
What does cause trouble is a blind fitted so that it fouls the ventilation flap or the handle, which is a fitting error rather than a product one and is avoided by using a matched blind.
The reveal decides how well a blind sits
A blind runs on the sash, and the reveal is the plastered shaft around it. The relationship between the two is what makes a blind look fitted or look added.
A reveal plastered hard up to the frame leaves no room for the blind’s side channels and its headbox, and a blind fitted afterwards then sits proud of the plaster with its fixings visible. A reveal formed with a small margin to the frame lets the blind sit within the opening and reads as part of it.
That margin is decided by whoever forms the linings, frequently a plasterer working after we have gone, and it is worth saying to them at the time. It costs nothing and it cannot be recovered without taking the plaster off.
Splayed reveals and blinds
A splayed reveal, wider at the room than at the roof, is the right detail for daylight and it interacts with a blind.
The blind runs on the sash, in the plane of the roof, so it sits at the top of a splayed shaft rather than at the room face. That is fine and it is worth picturing, because when the blind is down the splay is still open below it and light can reflect into the room off the splay itself.
In a bedroom where genuine blackout is the point, a shallower splay at the head and a deeper one at the sill gives most of the daylight benefit while keeping the blackout tight.
Insect screens, which fit the same way
Worth mentioning alongside, because it uses the same channels and the same timing argument.
A roof window open on a warm evening in a lit room is an efficient way of collecting insects, and a screen fitted into the same side channels solves it without stopping the ventilation.
Like a blind it is neater fitted with the window, and it can be added later.
Cost, in the shape of it
We publish no prices, and the shape of this one is simple.
A blind ordered with the window costs the blind. A blind added later costs the blind plus a visit, and sometimes plus making good a reveal that was plastered tight. A powered blind added later to a finished ceiling costs the blind, the visit, and either a battery or solar unit or the disruption of getting a cable in.
The difference is not enormous and it is entirely avoidable by deciding early.
What we ask first on a VELUX
We ask what the room will be used for and whether anybody will sleep in it, because that answers the blackout question before anything is ordered. Where blinds are wanted we order them with the window so the fixings are concealed and the fit is exact, and we raise the cabling question before the ceiling closes. Where a decision is not ready, we form the reveal so a blind can be added neatly later.
Nothing here is irreversible. Deciding early just makes it neater and cheaper.
Thinking about this job? We survey across Worthing, West Sussex and the South Downs and give you a fixed price before any work starts, with a 10-year workmanship guarantee.