Shutter Slat Size Guide | Compare Slat Styles & Light Control

🪟 Shutter Slat Size Guide

Choosing the Right Louvre for Your Home

When choosing plantation shutters, slat size isn’t just a visual preference — it affects how much light enters the room, how the panels are built, and how the shutters sit within the window recess.

Each slat size offers a different balance of privacy, light control, rail placement, and overall feel in the room. Larger slats allow more light and visibility but require more depth, which can push the shutter frame further into the room — making smaller spaces feel a little tighter. Smaller slats, on the other hand, sit closer to the window and maintain a neater visual profile — especially important in bay windows or rooms where space and light are key.

We’ll guide you through the pros and cons of each size to help you find the best fit for your space, style, and window type.

At a Glance – Why Slat Size Matters

✅ Light Control – Larger slats let in more light; smaller slats offer tighter closure
✅ Privacy – Narrower slats provide more privacy when partially open
✅ Recess Fit – Larger slats require the shutter to sit further forward in the recess
✅ Room Impact – Shutters that project further into the room can make small spaces feel tighter
✅ Rail Size – Slat size affects the size and symmetry of top, bottom, and mid-rails
✅ Mid-Rail Alignment – Larger slats increase the variation in mid-rail placement
✅ Slat-to-Glass Alignment – Smaller slats align more closely with window panes, especially important in bay windows
✅ Window Handle Clearance – Larger slats need more space; smaller slats are better where handles protrude
✅ Style & Proportion – Slat size influences the overall visual balance and whether the shutter feels classic or contemporary

📏 Slat Sizes We Offer

Every room, window, and aesthetic requires the right balance between visibility, privacy, and function. Below are the slat sizes we offer, along with where they work best and why.

🔹 47mm Slats

• Traditional look with narrow spacing
• Allows more slats per panel, offering maximum privacy and light filtering
• Only available in our Fermain and Sark hardwood ranges
• Best for smaller windows or period-style properties
• Can feel “busy” or heavy on tall panels

🔹 63mm Slats

• Our most popular and versatile size
• Ideal for bay windows and smaller recesses due to tighter frame position
• Balances light and privacy well
• Works with most ranges and room styles
• Preferred when handle clearance and alignment with glazing are a concern

🔹 76mm Slats

• Clean, modern look with wider light gaps
• Good for bedrooms, living rooms, and full height panels
• Still fits comfortably in most recesses
• Slightly greater variation in rail placement and panel height symmetry

🔹 89mm Slats

• Bold, open design for maximising light
• Best suited to tall windows and tracked doors
• Requires deeper recess and careful layout planning
• Visually striking in larger rooms

🔹 114mm Slats

• Statement slat for tall or dramatic windows
• Fewer slats = fewer light gaps = potential for room darkening
• Not available in MDF ranges
• Only suitable for very tall shutters or where visual impact is a priority

🧱 How Slat Size Affects Construction

Shutters aren’t built around the slat — they’re built around the entire panel, and slat size plays a key role in how the shutter is configured.

📐 Rails and Mid-Rails

• Each panel must contain a complete number of slats, meaning the top, bottom, and mid-rails must flex slightly in size to make that work
• Larger slats = fewer slats per panel, which can lead to taller rails to make panel the correct height
• Mid-rail positioning varies more with larger slats — alignment position may drift by up to half a slat

🪟 Bay Window Alignment

• In bays, glass pane alignment is especially important for both visual flow and external symmetry
• We always aim to align the mid-rail with window breaks (like sash lines or top opening panes)
• Smaller slats (like 63mm) help maintain closer alignment between shutters and the window glass

📏 Recess Depth and Frame Positioning

• Bigger slats require the panel to sit further into the room to avoid clashing with handles
• Smaller slats allow a tighter fit inside the recess, preserving sill space and a sense of openness
• Improper placement may impact how deep the frame appears and how much space you feel you’ve lost

🏠 Room Slat Size Recommendations

🪟 Bay Windows

• Recommend 63mm for better slat-to-glass alignment and frame positioning
• Keeps the shutter closer to the window and maintains sill space
• Avoid larger slats due to handle clearance issues and glass pane misalignment

🛏️ Bedrooms

• 63mm or 76mm depending on privacy needs and recess depth
• 76mm offers more light if paired with a mid-rail or blackout solution
• For improved room darkening, pair with Shutter and Shade

🛋️ Living Rooms

• 76mm or 89mm for wider, brighter appearance
• Consider 89mm in open-plan or south-facing rooms
• Match slat size to furniture scale and ceiling height for best impact

🍽️ Kitchens

• 63mm preferred for handle clearance and tight recesses
• Works well with café style shutters
• Helps maintain practical use of the window sill

🛁 Bathrooms

• Slat size secondary to material choice
• 63mm or 76mm works best for controlling moisture and privacy
• Pair with ABS Coated (Herm Range) or UK-Made (Wisley Range) waterproof options

🚪 Tracked Shutters & Bifold Doors

Tracked shutters — particularly those fitted across bifold doors or large openings — have slightly different requirements when it comes to slat size.

Because the panels are generally taller, a mid-rail is always required for structural strength. Larger slats can work well in these setups, especially where maximising light or creating a more open feel is important.

But slat size also affects how the doors function day to day:
✅ 76mm or 89mm slats are popular choices for tracked shutters — offering more light and fewer slats per panel
✅ Larger slats reduce weight and make folding smoother in larger formats
⚠️ However, the slats must be fully closed before folding the panels — this prevents slat damage

✅ We’ll plan your track system to ensure clearance, folding space, and symmetry are all optimised

📏 Mid-rail placement is calculated based on door height and rail visibility needs

For taller shutters, larger slats often look better proportionally — but our team will always advise based on your room, use case, and recess depth.

🧼 Cleaning Considerations by Slat Size

While all of our shutters are designed to be low maintenance, the slat size can affect how easy they are to clean — particularly in kitchens, bathrooms, and high-use areas.

Here’s what to consider:

• Larger slats (76mm, 89mm, 114mm) mean fewer slats per panel, so there are fewer gaps to dust — making them quicker and easier to clean
• Smaller slats (47mm, 63mm) offer tighter closure and more privacy but require more attention due to a greater number of slats per panel
• Always use a soft cloth, feather duster, or vacuum with a brush attachment to clean between slats
• Waterproof shutters (Herm, Wisley) can be cleaned with a damp cloth and mild detergent, then dried thoroughly
• Real wood and MDF shutters should be kept dry — only use a very lightly damp cloth when necessary, and never spray cleaners directly onto the surface

For best results:
• Focus on high-contact areas like tilt rods and handles
• Don’t forget to open the shutter panels and clean behind them, including inside the frame
• Use the crevice tool on your vacuum cleaner to clean between the frame and window

🪵 Engineered Stiles

Most of our shutters are built with engineered stiles, which are made by laminating multiple layers of timber together. This process improves dimensional stability, reducing the risk of warping over time.

Engineered stiles help your shutters maintain their shape and alignment, especially on taller panels, and contribute to the overall durability of the installation, ideal for the long-term performance of full height shutters.

🪚 Traditional Mortise and Tenon Joints

All of our plantation shutters are built using traditional mortise and tenon joints — a time-tested carpentry method that provides superior strength and long-term durability.

In this method, the rail slots directly into the stile of the shutter frame, creating a solid and secure join without the need for dowels, glue blocks, or short-lived fastenings. This approach:

• Minimises movement and warping over time
• Reinforces the frame’s overall strength
• Ensures a longer-lasting, high-quality finish

📍 Want to learn more about how our shutters are constructed?

🇬🇧 UK-Made Shutters – The Wisley Range

Our Wisley range of UK-manufactured shutters offers a combination of style, speed, and sustainability — without compromising on quality.
• ✅ Made in the UK – great for local support and reliability
• ✅ Fast lead time – delivery and installation in as little as 5 weeks
• ✅ Eco-friendly – significantly lower carbon footprint than imported alternatives
• ✅ Waterproof – suitable for bathrooms, kitchens, and humid environments
• ✅ Wide colour choice – available in nine stunning colours

UK-made shutters are an ideal solution for customers who need their shutters quickly, want to minimise their environmental impact, or simply prefer to buy British.

📍 Interested in faster delivery or sustainable options?

🆓 Free Temporary Blinds While You Wait

When you order plantation shutters from us, we offer complimentary temporary blinds to cover your windows during the manufacturing period — so you’re never left without privacy or control over light.

These temporary blinds are:

• Free With A Shutter Purchase
• Easy to fit
• Neutral in colour and discreet in appearance
• Ideal for maintaining privacy and comfort while your shutters are being made

📍 Just one more way we aim to make your experience smooth and stress-free.

🤝 Our Service Commitment

At Surrey Blinds and Shutters, we combine quality craftsmanship with trusted service, ensuring every customer receives a smooth, professional experience from start to finish.

✅ Our Own In-House Fitting Team

All of our shutters are installed by our own experienced fitters — we never subcontract. You’ll deal with the same trusted team throughout your journey.

✅ Post-Installation Checklist

Once your shutters are fitted, we carry out a detailed checklist to make sure everything is perfect and you’re completely happy before we leave.

✅ 10-Year Shutter Guarantee

We stand by the quality of our products. That’s why all our shutters come with a full 10-year guarantee for your peace of mind.

✅ UK-Made Shutters in as Little as 5 Weeks

Need shutters sooner? Our UK-made range can be manufactured and installed in as little as five weeks – ideal if you’re working to a deadline.

✅ Established in 2009

We’ve been proudly trading since 2009, bringing years of hands-on experience to every consultation, installation, and customer we work with.

✅ Free Temporary Blinds While You Wait

Waiting for shutters to be made? We offer complimentary temporary blinds so you’re never without privacy or light control during the lead time.

Whether you’re fitting out a single bay or updating your whole home, we’re here to help from start to finish – with a team that genuinely cares.

How to Get Started

Book your free consultation today and let our experts guide you through the best options for your space.

📞 Call us on 01483 608 274
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Big Yellow, Office 4, 113–115 Oyster Lane
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Schedule your consultation today and let us help you create a stunning look for your windows.