Blackout lining
A specialist lining is added behind the face fabric. This lets you choose the decorative fabric for its colour, pattern and texture while the lining provides the light-blocking layer.
Fabric Guides & Advice
Blackout Curtains & Blinds: How to Choose
Blackout lining can make bedrooms, nurseries and media rooms considerably darker, but the fabric is only part of the solution. The way a curtain or blind fits the window determines how much light can still enter around the edges.
What Does “Blackout” Really Mean?
A blackout lining or blackout fabric is designed to prevent light passing through the textile itself. That does not automatically mean a room will become completely dark.
Light can still enter above, below and beside a curtain or blind, through a centre opening, or around the gaps needed for hardware and operation. For that reason, the best result comes from combining the right lining with careful measuring, generous coverage and suitable installation.
Think “room darkening”, not a guaranteed 100% blackout.
If near-total darkness is important, tell your maker at the start. The window shape, recess, track or pole position and the possibility of layering treatments can then be considered as part of the design.
Blackout Lining vs Blackout Fabric
There are two common ways to create a light-blocking window treatment, and they give you different levels of design freedom.
Blackout or dim-out fabric
Some fabrics are manufactured with light-blocking properties built into the textile or its backing. Always check the exact product specification: “dim-out” and “blackout” are not necessarily interchangeable descriptions.
For designer curtains and Roman blinds, adding a suitable blackout lining is often the most flexible approach because it does not restrict you to a small group of inherently light-blocking decorative fabrics.
Blackout Curtains or a Blackout Roman Blind?
Both can work very well. The best choice depends on the window, the room and how dark you want it to be.
Blackout curtains
- Can overlap the sides of the window substantially.
- Work well on wide or full-height windows.
- Offer a softer, more decorative finish.
- Can use a wide choice of suitable face fabrics with blackout lining.
- Performance improves when the track or pole allows the curtains to sit close to the wall and overlap the opening well.
Blackout Roman blinds
- Give a neat, tailored finish with less fabric in the room.
- Suit many smaller windows and spaces where curtains would feel bulky.
- Can be fitted inside or outside a recess.
- An outside-recess installation can provide extra overlap around the opening.
- Inside-recess blinds naturally require operating clearance, so small side gaps should be expected.
Where Does Light Leakage Occur?
Once light is prevented from passing through the textile, the remaining challenge is usually light travelling around it.
Insufficient overlap allows light around the window opening. This is especially noticeable with bright morning or evening sun.
A gap between the wall and track, pole or blind can produce a bright line at the top.
A blind or curtain that finishes too short may allow a noticeable strip of light beneath it.
The centre join needs enough overlap or closure to avoid a vertical shaft of light.
A blind needs enough clearance to operate, so an inside-recess fit normally leaves small gaps around the edges.
Doors, adjoining spaces and electronic or decorative lighting can remain visible even when the window treatment is performing well.
Inside-Recess or Outside-Recess Blackout Blind?
Inside the recess
This gives a clean, integrated appearance and leaves the surrounding wall visible. Because the blind must clear the recess and hardware, some edge light is normal.
Outside the recess
Mounting the blind over the opening can provide greater overlap at the top, sides and bottom. Where the wall and window proportions allow it, this can improve room darkening.
Check handles, vents, projecting sills, radiators and other obstacles before deciding which position is practical.
Curtain Track & Pole Positioning
For blackout curtains, coverage is normally more important than simply choosing a thicker lining. A track or pole positioned so the curtains extend beyond the opening and sit reasonably close to the wall can help reduce light around the top and sides.
- Allow enough width beyond the window for useful side overlap.
- Consider whether the curtains can return towards the wall at the outer edges.
- Make sure the pair closes with enough overlap at the centre.
- Choose an appropriate finished drop for the sill or floor.
- Take radiators, handles and furniture into account.
- Discuss unusually shaped bays or recesses with the maker before ordering.
Avoid universal centimetre rules.
Window construction and hardware vary too much for one fixed allowance to work everywhere. Measure for the actual track, pole, recess and finished treatment, using the instructions for the system you intend to order.
Layer a Blind and Curtains for Better Room Darkening
Where reducing light is especially important, combining a blackout-lined blind with curtains can be more effective than asking one treatment to do everything.
Blind at the window
The blind reduces direct light through the central part of the opening and gives privacy with a compact treatment.
Curtains outside
Curtains add overlap beyond the opening and can help cover edge gaps left around the blind.
More control and flexibility
You can use the blind alone during the day and close both treatments when you want the darkest practical result.
Where Blackout Treatments Are Most Useful
Bedrooms
Useful where early sunrise, street lighting or bright neighbouring properties make a room difficult to darken.
Nurseries & children's rooms
Helpful when daytime naps or long summer evenings make control of daylight especially useful.
Media rooms
Reducing daylight can make television and projection screens easier to view and reduce glare.
Rooms needing privacy
Opaque linings can prevent silhouettes and views through the face fabric when the treatment is closed.
Do Blackout Curtains Help With Heat?
Adding a lining creates another layer at the window and can help reduce draught sensation and some heat transfer, particularly when the treatment gives good coverage. However, the result depends heavily on the window, fabric, lining and installation.
If thermal performance is your main concern, choose and specify the treatment for that purpose rather than assuming every blackout lining provides the same level of insulation.
Measuring for Blackout Curtains & Blinds
The old version of this guide used fixed allowances for recess blinds, outside-recess blinds, poles and curtain hems. Those figures can be misleading because different systems and windows need different clearances.
Instead, decide first what you are ordering and where it will be fitted. Then measure according to that treatment and hardware.
- For curtains, establish the finished track or pole position before taking final width and drop measurements.
- For a Roman blind, decide inside-recess or outside-recess before measuring.
- Measure the opening in more than one place where walls or recesses may be out of square.
- Check handles, sills, radiators and other projections.
- If maximum darkness is important, discuss the required overlap with the maker before ordering.
- Do not order from approximate window dimensions where the finished treatment is made to measure.
Choosing the Face Fabric
A blackout lining means you do not necessarily need a dark decorative fabric. Pale linens, colourful prints, patterned velvets and many other suitable furnishing fabrics can all be considered, provided the face fabric is appropriate for the treatment and compatible with the chosen lining.
Order a sample before committing and check how the cloth looks in the room by day and under artificial light. Our Fabric Buying Guide covers composition, width, pattern repeat, samples and other useful pre-order checks.
Blackout Curtains & Blinds FAQs
Will blackout curtains make a bedroom completely dark?
Not necessarily. A blackout lining can prevent light passing through the curtain, but light may still enter around the top, sides, bottom and centre opening. Installation and overlap are critical when you want the darkest possible room.
Are blackout curtains better than blackout blinds?
Neither is automatically better. Curtains can provide generous overlap around a window, while a Roman blind gives a compact tailored treatment. The best solution depends on the opening and may sometimes be a combination of both.
Is an outside-recess blind better for blackout?
It can be, because it may overlap the opening more than a blind fitted inside the recess. The best choice still depends on wall space, handles, sills and the proportions of the window.
Can I use a patterned fabric with blackout lining?
Yes, where the face fabric is suitable for curtains or Roman blinds and compatible with the lining. The lining does the light-blocking work, so the decorative fabric can be selected primarily for the room and design.
Can I have both blackout blinds and curtains?
Yes. Layering is often one of the most effective approaches when strong room darkening is important, while also giving you more flexibility over privacy and appearance during the day.
Related Guides
Planning Made-to-Measure Blackout Curtains?
Many suitable TM Interiors fabrics can be configured as made-to-measure window treatments with lining options. For more bespoke requirements, ask us to check the fabric, lining and window details before you order.
