If you’ve been shopping for blackout curtains or a blackout blind, you’ve probably heard (or assumed) the same thing we’re hearing more and more in Cambridgeshire:
“Blackout means the room will be pitch black, right?”
It’s a totally fair expectation, but in real homes, “blackout” usually refers to the fabric, not the entire window installation. Here’s what that means, why light still gets in, and what we recommend if you want a genuinely dark bedroom.
What “blackout” usually means
In most cases, blackout means the material is designed to block the vast majority of light passing through the fabric itself.
That’s different from saying the whole window will be sealed from light.
Even with true blackout fabric, you can still get light coming in from:
- The sides of the blind or curtain
- The top (especially with roller blinds)
- The bottom (common on doors and tall windows)
- The overlap where curtains meet in the middle
Why a blackout blind/curtain can still leave the room bright
1) Light gaps around the edges
This is the big one. Windows aren’t perfectly light-tight, and most blinds need a little clearance to operate smoothly. That small gap is enough for sunlight to “halo” around the edges.
2) Fitting position matters (recess vs face fit)
- Recess fit (inside the window recess) often looks neat, but it can leave small gaps at the sides.
- Face fit (outside the recess) can reduce gaps by covering more of the wall around the window.
3) Curtains need the right track/pole and the right return
Even with blackout lining, curtains can leak light if:
- The curtain doesn’t overlap enough at the centre
- The track/pole sits too far from the wall
- There’s no “return” at the sides (where the curtain wraps back to the wall)
4) Room conditions (summer mornings, streetlights, new builds)
In many Cambridge and Cambridgeshire new-build areas, we see:
- Large windows and patio doors
- Bedrooms facing early morning sun
- Streetlights and security lighting outside
So even a small gap can feel like a lot.
The difference between “blackout fabric” and “total blackout”
Here’s a simple way to think about it:
- Blackout fabric: blocks light through the material.
- Total blackout setup: reduces light through the material and around the edges.
If your goal is a darker room for sleep (especially for children’s rooms, shift workers, or light sleepers), you usually need a combination of the right product and the right fitting approach.
How to get a genuinely darker room (our practical recommendations)
Option A: Blackout roller blind + cassette and side channels
A roller blind in blackout fabric is a great start, but for a noticeably darker room you’ll usually want:
- A cassette/headbox at the top
- Side channels to reduce edge light
This is one of the best solutions when you want a clean, modern look.
Option B: Blackout Roman blind + blackout curtains (layering)
Layering is brilliant for bedrooms:
- Roman blind for a tailored look
- Curtains to cover side gaps and add warmth
It also improves insulation and helps with sound.
Option C: Curtains with blackout lining + the right track and returns
If you prefer curtains, we’ll normally look at:
- A track that sits close to the wall/ceiling
- Enough fabric width for good “stack back” and overlap
- Side returns so the edges sit back against the wall
Option D: Add a pelmet or consider a different style for tricky windows
For some windows (especially in new builds), a pelmet or a different fitting method can make a big difference.
What to ask for when you’re shopping
If you’re speaking to a showroom or browsing online, these questions help set expectations:
- Is the fabric blackout, or is the system designed for total blackout?
- How much light gap should I expect at the sides/top/bottom?
- Would you recommend recess fit or face fit for my window?
- Do I need side channels/cassette/pelmet for the result I want?
Want help choosing the right blackout solution?
If you’re in Cambridge or Cambridgeshire (including new-build areas), we can recommend the best approach for your room, your window type, and how dark you want it.
- Bring a few photos of your windows, or
- Book a home visit for measuring and advice
Get in touch with Cambridge Interiors and we’ll help you get the result you’re expecting, without the disappointment.