Knowledge
What to consider when designing blackout
Effective blackout depends on more than the fabric. Get an overview of overlap, tracks, light gaps and building details.
Short answer
Blackout is a whole made of textile, overlap, closures and track system. Describe the required blackout level specifically per room, check every place light can pass, coordinate tracks and operation early — and test the solution with a mock-up before repeating it across many rooms.
Define the required blackout level
Some rooms only need reduced daylight, while others must support projection, sleep or special activities. The requirement should be described specifically, because complete blackout places greater demands on detailing.
A vague requirement such as “the room must be able to black out” often leads to disputes at handover. Describe the situation instead: what must be possible in the room, at which times, and how much residual light is acceptable.
Check for light around the solution
Even a light-tight textile can produce insufficient blackout if light passes at the sides, head, bottom or between curtain panels. Overlap, return to wall, pelmet, side guides and the geometry of the room must be assessed as a whole.
Bright surfaces around the opening amplify the perception of residual light, because even narrow gaps reflect into the room. The details at the edges of the opening therefore matter more than the colour of the fabric.
Coordinate tracks and operation
The track's position, number of tracks and distance to the glass affect the result. Motorisation can give consistent operation, but requires early clarification of power, service access and control.
In rooms with fixed scenarios — presentation, projection, AV — blackout should be designed together with lighting and AV control, so the whole room can be set in one action.
Test critical rooms
Where requirements are strict, carry out a mock-up or trial installation. It makes light gaps visible and lets the details be adjusted before the solution is repeated in many rooms.
Design checklist
- Blackout level described specifically per room type
- Light gaps at sides, head, bottom and between panels assessed
- Overlap, return and any pelmet/side guides detailed
- Track position and track count coordinated with ceiling details
- Operation clarified — manual or motorised, individual or scene-based
- Mock-up planned for rooms with strict requirements
Frequently asked questions
Is a dark textile enough to black out a room?
No. Even a light-tight fabric does not automatically provide full room darkening. Light can enter at the sides, top, bottom and between curtain panels, so the entire window treatment must be planned.
What is a light gap?
A light gap is any opening where light passes around the curtain — at the sides, top, bottom or between panels. It can be reduced with greater overlap, side channels or returns towards the wall.
When is a mock-up necessary?
A mock-up is recommended where room-darkening requirements are high or the same solution will be repeated in many rooms. A trial installation reveals light gaps and allows adjustments before full production.
Must blackout always be motorised?
No. Motorisation is relevant for tall bays, heavy textiles or preset room settings — otherwise manual operation can be both simpler and more robust in daily use.
Do you have a specific project?
Upload the material or book a project review with CIS Nordic.