How Much Clearance Do You Need for Different Blind Types?

You’ve chosen the perfect fabric, picked your ideal colour, and even found a blind style that suits your space — but when it comes time to install, something’s not quite right. Maybe the blind scrapes the windowsill, bunches up at the bottom, or lets in more light than you'd like. Sound familiar? If so, you're not alone. One of the most common frustrations for homeowners buying new blinds is discovering—too late—that they haven’t left enough clearance for the blind to fit or function properly.

Why Clearance Matters

Getting your measurements right isn’t just about squeezing a blind into a space — it’s about ensuring smooth operation, a sleek appearance, effective light control, and long-lasting performance. Too little clearance and you could end up with a blind that rubs against walls, overlaps awkwardly, or looks oddly proportioned. Too much, and you risk light leaks, exposure gaps, or an ill-fitting appearance that spoils the clean lines of your room.

Proper clearance ensures your blinds can roll, fold, tilt, or draw exactly as designed — without snagging, sticking, or sagging.

What You'll Learn in This Guide

In this blog post, we’ll take the guesswork out of measuring and help you avoid the most common blind-buying mistakes. You’ll learn the ideal clearance requirements for five of the most popular blind types:

• Roller Blinds


• Roman Blinds


• Cassette Blinds


• Venetian Blinds


• Vertical Blinds

We’ll also share top tips for accurate measuring, cover common pitfalls to avoid, and break down how recess fit (inside the window frame) and exact fit (outside the window recess) can impact your clearance needs.

Whether you’re going DIY or ordering made-to-measure from a trusted UK manufacturer like DotcomBlinds, knowing how much space your blinds need is key to a flawless finish.

Understanding the Basics: Recess Fit vs. Exact Fit

Before we explore specific clearance needs, it's important to understand the two main ways blinds can be installed: Recess Fit and Exact Fit (also known as Face Fix).

Recess Fit means the blind is installed inside the window opening. The main consideration here is the depth of the recess, as some blind types need more room to operate smoothly. This method offers a clean, streamlined look that sits flush within your window frame.

Exact Fit, on the other hand, is fitted outside the recess, on the wall or window architrave. This requires careful attention to side, top, and bottom overlap for effective light blocking and can visually enhance the size of your window.

Clearance Breakdown for Roller Blinds

Overview

Roller blinds are a sleek, practical, and hugely popular choice for homes across the UK. Consisting of a single piece of fabric that winds around a tube, roller blinds are available in a variety of styles including blackout, thermal, and screen fabrics. They’re ideal for minimalists and can be chain-operated, spring-loaded, or motorised for added convenience. However, their simplicity hides an important detail: they still need the right amount of clearance to function flawlessly — especially in tighter window spaces.

Recess Fit Clearance

To fit roller blinds neatly inside the window recess, you’ll need to ensure there’s sufficient depth for both the roller tube and operating mechanism (whether manual or motorised).

• Minimum Recess Depth: Typically, roller blinds require at least 6–7 cm of recess depth to accommodate the full fitting, including the brackets and rolled-up fabric.


• Window Handle Interference: If your window has prominent handles, you may need an additional 2–3 cm of clearance to prevent the blind from catching or bunching. Alternatively, consider using spacer brackets or opting for an exact fit installation.


• Measuring Tip: Use a metal tape measure and check the narrowest point of the recess (especially if your walls aren’t perfectly square). Always measure depth in multiple spots — left, centre, and right — and base your decision on the shallowest depth.

Exact Fit (Face Fix) Clearance

For an exact fit installation — where the blind is mounted above and across the window frame — the goal is maximum coverage and visual balance.

• Recommended Width Overlap: Add at least 5–10 cm on each side of the window to reduce light bleed and improve privacy.


• Recommended Height Overlap: Allow 10–15 cm above the window to ensure the blind clears the glass when fully rolled up, and 5–10 cm below the window or sill for full coverage.


• Obstacle Check: Be sure to leave enough space around the blind to avoid clashing with nearby walls, radiators, curtain poles, or door frames. A blind that snags on furniture or architectural details won’t just look wrong — it may also wear out faster.

Special Considerations

Roller blinds may look simple, but several factors can affect their clearance needs:

• Motorised Options: Battery-operated or mains-powered roller blinds often feature slightly bulkier headrails or integrated motors. Double-check the product dimensions before choosing a recess fit.


• Blackout Linings: These can make the fabric thicker, adding to the rolled-up diameter. Consider a cassette-style roller or side channels for total blackout performance.


• Child Safety Devices: All manually operated roller blinds must be fitted with cord safety devices under UK law. Ensure there’s enough wall space near the control side to anchor these devices at the recommended height.


• Tilt & Turn Windows: If your window opens inward, a recess fit blind may block the movement. In such cases, opt for an exact fit blind or choose a blind that can be mounted directly to the window sash — like Click Fit or Perfect Fit alternatives.


• Double Roller Blinds: If you're layering two blinds (e.g., a sheer and a blackout), you'll need extra depth — often 10–12 cm — to fit the dual brackets.

Clearance Breakdown for Roman Blinds

Overview

Roman blinds are a timeless and elegant window dressing, often chosen for their soft fabric folds and classic style. When raised, the fabric gathers neatly into horizontal pleats, creating a sophisticated stacked look. These blinds are ideal for living rooms, bedrooms, and dining spaces where style matters just as much as functionality. While they look plush and decorative, Roman blinds still require precise clearance to operate smoothly and look their best — particularly when mounted inside a recess.

Recess Fit Clearance

For Roman blinds fitted inside the recess, depth matters more than you might expect. These blinds don’t roll up like roller blinds — they fold upwards, meaning the stack of fabric sits at the top of the window when the blind is raised.

• Minimum Recess Depth: Roman blinds typically require a minimum recess depth of 7–9 cm to accommodate the headrail, operating mechanism, and fabric stack.


• Window Handle Interference: As the blind hangs close to the windowpane, prominent window handles may cause it to bulge or tilt. If your handles protrude more than 2–3 cm, consider a spacer bracket, switch to face fix, or choose a different blind style better suited to shallow recesses.


• Measuring Tip: Always measure the depth at multiple points inside the window recess and note the shallowest point. Check for obstructions like tiles, trim, or handles that could reduce usable space.

Exact Fit (Face Fix) Clearance

Face fixing Roman blinds outside the recess offers greater flexibility and often a more decorative, layered effect — particularly when paired with curtains.

• Recommended Width Overlap: Add at least 5–10 cm to each side of your window to maximise privacy and minimise light seepage.


• Recommended Height Overlap: Allow 10–15 cm above the window to ensure the full fabric stack clears the glass when raised, and 5–10 cm below the window for full-length coverage.


• Obstacle Considerations: Be aware of surrounding features such as coving, radiators, light switches, or picture rails that might interfere with the blind’s drop or fixings.

Special Considerations

Roman blinds come with a few unique traits that can impact clearance and fit:

• Motorised Options: Motorised Roman blinds may include a slightly bulkier headrail or power supply, so always check the product specifications. Face fixing is often the better choice for motorised versions if recess depth is limited.


• Blackout Linings: Adding a blackout lining increases the thickness and weight of the blind, which can enlarge the fabric stack when raised. Ensure you have enough headspace to accommodate this without blocking the view.


• Child Safety Devices: Chain-operated Roman blinds are required by UK law to include child safety cleats or tensioners. Ensure you leave space next to the blind for these to be fitted securely at the correct height.


• Tilt & Turn Windows: Roman blinds are not always ideal for tilt and turn windows, especially in recess fit, as the fabric can get in the way of the opening mechanism. In these cases, face fix outside the recess or alternative blind styles (like Perfect Fit or Click Fit) are often more practical.


• Stack Height Considerations: The stacked fabric at the top of a Roman blind can block a portion of the window even when fully raised. To reduce this, some homeowners install the blind higher above the window frame, allowing the stack to clear the glass entirely.

Clearance Breakdown for Cassette Blinds

Overview

Cassette blinds are a modern and stylish blind system that encases the fabric roll within a sleek aluminium or plastic cassette. This integrated design conceals the roller mechanism and gives the blind a neat, finished look. Cassette blinds are particularly popular in blackout or light-sensitive environments like bedrooms, nurseries, and home cinemas. Some models come with side channels to further block light — but this premium functionality means cassette blinds often require precise and generous clearance to install correctly.

Recess Fit Clearance

For cassette blinds installed inside the window recess, clearance is crucial to ensure the cassette and side channels sit flush without restricting movement.

• Minimum Recess Depth: Most cassette blinds require a minimum depth of 7.5–9.5 cm, especially if you’re including side channels for blackout performance.


• Window Handle Interference: Prominent handles can push the blind outwards or prevent it from dropping cleanly. If your handles project more than 2 cm, consider using spacer brackets, adjusting the recess fitting, or switching to a face fix installation.


• Measuring Tip: When measuring depth, ensure you account for the full projection of the cassette (not just the blind fabric) and measure at multiple points across the recess to account for any narrowing.

Exact Fit (Face Fix) Clearance

For face fixing, cassette blinds become a feature in themselves and can offer outstanding light-blocking results when correctly positioned.

• Recommended Width Overlap: Add at least 7–10 cm on each side of the window to allow the cassette and fabric to fully cover the opening without light gaps.


• Recommended Height Overlap: Allow for 15–20 cm above the window to fit the cassette box and give the blind space to retract fully without obstructing the glass. Allow 5–10 cm below the sill if needed for full coverage.


• Obstacle Considerations: Cassette blinds can be bulkier than standard roller blinds, so ensure there's clearance from walls, pelmets, radiators, or door frames — especially if you're installing above or around deep window recesses.

Special Considerations

Cassette blinds come with several unique features and optional upgrades, each of which may affect your clearance requirements:

• Motorised Options: These blinds often come with integrated motors within the cassette. While discreet, motorised options can add 1–2 cm to the overall cassette depth, so always check product specifications before deciding on a recess fit.


• Blackout Linings & Side Channels: Designed to block out light completely, blackout cassette blinds use side channels that add extra width and depth. Ensure your recess is wide enough to accommodate the full frame, or opt for face fix if not.


• Child Safety Devices: As with all manually operated blinds, cassette blinds with chains or cords must include child safety fixings. Make sure there’s room on the side of the blind for secure and accessible placement.


• Tilt & Turn Windows: These windows can pose a challenge for recess-fitted cassette blinds, particularly when side channels are used. If your window opens inward, it’s often better to face fix the blind above the recess to allow free window movement.


• Aesthetics: Face-fitted cassette blinds can give a high-end, built-in look if aligned neatly with the window frame. Take time to plan the overlaps carefully for a visually balanced finish.

Clearance Breakdown for Venetian Blinds

Overview

Venetian blinds are a versatile and stylish option, featuring horizontal slats that can be tilted to control light and privacy or raised completely for a clear view. Available in materials like aluminium, real wood, and faux wood, they suit a variety of settings — from sleek kitchens to cosy home offices. Their precise light control and classic design make them a perennial favourite, but their moving parts and slat stack height mean measuring accurately for clearance is essential to achieve the right fit and function.

Recess Fit Clearance

When fitting Venetian blinds inside the window recess, you’ll need enough depth to house the headrail, tilting mechanism, and stacked slats when the blind is raised.

• Minimum Recess Depth: Most Venetian blinds require a minimum recess depth of 5–7 cm, depending on slat width and headrail design. Wider slats (e.g., 50mm) often need more depth than narrower 25mm slats.


• Window Handle Interference: Window handles that protrude more than 2 cm can disrupt the slat drop or cause the blind to sit unevenly. In this case, consider face fixing, using spacer brackets, or choosing a Perfect Fit frame if you want to retain inward window access.


• Measuring Tip: Use a rigid metal tape and measure the depth at three points — top, middle, and bottom — then work with the shallowest measurement to avoid fitting issues.

Exact Fit (Face Fix) Clearance

Face fitting Venetian blinds outside the recess gives you flexibility with spacing and can make the window appear larger.

• Recommended Width Overlap: Allow at least 5–7 cm on each side of the window to ensure the slats fully cover the glass and limit light gaps when tilted.


• Recommended Height Overlap: Aim for 10–15 cm above the window so the blind can be fully raised without blocking the view, and 5–10 cm below the window for full drop coverage.


• Obstacle Considerations: Venetian blinds, particularly wood or faux wood versions, can be heavier and bulkier, so make sure there's enough space around the fitting area to avoid clashing with picture rails, sockets, radiators, or door frames.

Special Considerations

Venetian blinds come in various styles and materials, each with unique installation factors that can impact clearance:

• Motorised Options: Less common but available, motorised Venetian blinds may require a larger headrail or battery pack. Check dimensions carefully if planning a recess fit.


• Blackout Limitations: Venetian blinds do not fully block light due to the nature of the slats, so while they don’t require blackout linings, they aren’t suitable where total darkness is needed. You might consider pairing with curtains or a cassette blind.


• Child Safety Devices: As with all corded blinds, Venetian blinds must be installed with child safety cleats or chain tensioners. These must be placed at least 1.5 metres from the floor — so be sure there’s room near the control side to meet regulations.


• Tilt & Turn Windows: Standard Venetian blinds can obstruct inward-opening windows if recess fitted. Consider Exact Fit installation, or explore Click Fit or Perfect Fit Venetian blinds, which mount directly to the window frame without screws and move with the window itself.


• Stack Height: The stacked slats when the blind is raised can obscure part of the window. If this is a concern, opt for smaller slats (e.g., 25mm) which produce a smaller stack height than wider ones.

Clearance Breakdown for Vertical Blinds

Overview

Vertical blinds are a practical and popular choice for large windows, sliding doors, and commercial spaces. Made from individual fabric slats that hang vertically from a top-mounted headrail, these blinds tilt and draw sideways to control light and privacy. They’re especially effective at covering wide expanses of glass and can be made from light-filtering, dim-out, or blackout fabrics. Due to their side-draw movement and headrail mechanics, accurate clearance planning is crucial for smooth, tangle-free operation.

Recess Fit Clearance

Vertical blinds can work well inside a window recess, but the size and movement of the louvres require sufficient space, especially at the top.

• Minimum Recess Depth: Typically, vertical blinds require a minimum recess depth of 7–8 cm to fit the headrail, louvre hooks, and allow for unobstructed slat rotation.


• Window Handle Interference: Large or protruding handles can interfere with the slats as they draw or rotate. If handles extend more than 2 cm, consider using spacer brackets, mounting the blind outside the recess, or using shorter slats to avoid obstruction.


• Measuring Tip: Measure the depth at the top of the recess where the headrail will be mounted — this is critical, as any protrusions or narrowing at the top may prevent correct fitting.

Exact Fit (Face Fix) Clearance

Face fixing vertical blinds is ideal when you want full coverage or are working with a shallow or uneven recess.

• Recommended Width Overlap: Add at least 7–10 cm on either side of the window to prevent side light gaps and allow the slats to draw fully open without revealing the frame.


• Recommended Height Overlap: Allow 10–15 cm above the window to position the headrail comfortably and let the slats stack up when drawn open. Allow 5–10 cm below the sill to ensure full coverage if not stopping at a ledge.


• Obstacle Considerations: Vertical blinds need side clearance for slat movement and stacking. Be mindful of nearby walls, radiators, furniture, or curtains, especially if the blind opens to one side only.

Special Considerations

Vertical blinds come with a few unique clearance and usage considerations that may influence your installation method:

• Motorised Options: Motorised vertical blinds are growing in popularity and typically use a deeper headrail system to house the motor. If recess fitting, ensure your depth can accommodate this — otherwise, opt for face fix.


• Blackout Fabrics: While vertical blinds can be made with blackout fabric, light may still seep through slat gaps unless paired with overlapping slats or installed with generous side overlaps. Recess depth also needs to account for thicker blackout materials.


• Child Safety Devices: UK regulations require cord or chain tensioners to be fixed securely at a safe height. Make sure there’s wall space adjacent to the control mechanism for safe and legal fitting.


• Tilt & Turn Windows: These windows pose a challenge, particularly if they open inward and the blind is recess-fitted. In such cases, consider face fixing the blind higher up on the wall or switching to Perfect Fit or panel blinds for better window access.


• Stacking Side: Vertical blinds can be configured to split in the middle or stack to one side when open. Ensure there’s enough space on your chosen stacking side to accommodate the gathered slats — this is especially important for face fix blinds on narrow walls or tight corners.

General Measuring Tips for Success

Getting the right fit starts with accurate measuring. Whether you're opting for a recess fit or an exact fit, precision is key.

• Always measure in at least three places — for width, measure at the top, middle, and bottom; for height, check the left, centre, and right. Use the smallest measurement for recess fits to ensure a clean installation, or the largest for exact fit to maximise coverage.


• Use a metal tape measure for better accuracy, as fabric or plastic tapes can stretch or sag.


• Double-check your measurements before ordering — mistakes at this stage can be costly.


• Consider any potential obstructions, such as window handles, radiators, sills, or nearby furniture.


• If you're ever unsure, consult a professional or refer to the supplier’s own measuring guide to ensure your chosen blind will work beautifully in your space.

Common Clearance Mistakes to Avoid

Even a small oversight can lead to big frustrations when fitting blinds. Here are some of the most common clearance mistakes:

• Not accounting for window handles, which can interfere with the blind’s operation.


• Forgetting about nearby obstacles like radiators, furniture, or deep window sills that can block movement or access.


• Failing to check if the window is square — uneven recesses can affect how well a blind fits or hangs.


• Assuming all blind types require the same clearance — each style has its own unique requirements, so always check before you buy.

Clearance Makes All the Difference

When it comes to fitting blinds, clearance is everything. It’s the difference between a blind that glides smoothly, looks professionally installed, and lasts for years — and one that rubs, sags, or lets in unwanted light. Whether you’re going for a sleek recess fit or a bold exact fit, measuring accurately and understanding the space your blind needs is key to both functionality and aesthetics.

Take the time to measure carefully, consider any obstacles, and choose a blind style that complements both your window and your lifestyle. The process doesn’t need to be complicated — just precise.

Ready to choose your perfect blinds?

Explore DotcomBlinds’ wide range of made-to-measure blinds, from roller and Roman blinds to cassette, Venetian, and vertical styles. With free samples available to order, you can confidently find the right colour, texture, and finish before you buy.