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Window Sills – Internal & External UPVC Boards, Capping & Covers
Upgrade your home with our full range of window sills, designed to offer a sleek, durable, and low-maintenance finish for any interior or exterior space. Whether you’re replacing old timber boards or finishing off new windows, we provide everything you need — all in one place.
🏠 Internal Window Sills
Our internal window sills are made from high-quality UPVC and available in a variety of styles and sizes. Perfect for living rooms, kitchens, bathrooms, or office spaces. Easy to cut and install, with a clean, professional look.
🌧 External Window Sills
Built to withstand the elements, our external window sills are waterproof, UV-resistant, and designed for long-term performance. Ideal for protecting the base of your windows while enhancing curb appeal.
🔧 Capping Boards
Need a quick refresh? Use our window capping boards to cover up existing sills without the need for full removal. A smart and cost-effective solution for renovations.
🧩 Sill Cover Boards
Slim, lightweight, and durable — sill cover boards are perfect for DIY upgrades or large-scale trade projects. Available in a variety of widths, colours, and finishes.
🧱 End Caps & Sill Accessories
Complete your installation with our range of end caps and accessories. These finishing touches ensure your window sills look neat, secure, and fully sealed.
✔ Why Choose Our Window Sills?
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Maintenance-free UPVC – no painting or sealing required
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Range of lengths and depths available (100mm to 400mm)
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Available in white, anthracite grey, black ash, and more
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Easy to install – suitable for glue, screws, or silicone
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Perfect for home improvements, new builds, and commercial use
Browse our collection today and find the right solution for every window project — from internal sills to external covers, we’ve got you covered.
Window sills
Anthracite Grey UPVC 1.25m x 9mm Capping Board – Depth Options: 150mm to 300mm
In stock
£22.24 – £38.51 (Vat inc.)
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This product has multiple variants. The options may be chosen on the product page
Anthracite Grey UPVC 1.25m x 9mm(2 Pack)Capping Board – Depth Options: 150mm to 300mm
In stock
£33.35 – £57.76 (Vat inc.)
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This product has multiple variants. The options may be chosen on the product page
Anthracite Grey UPVC 1.25m x 9mm(4 Pack)Capping Board – Depth Options: 150mm to 300mm
In stock
£66.72 – £115.53 (Vat inc.)
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This product has multiple variants. The options may be chosen on the product page
Anthracite Grey UPVC 1.5m x 9mm Capping Board – Depth Options: 150mm to 300mm
In stock
£22.86 – £39.58 (Vat inc.)
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This product has multiple variants. The options may be chosen on the product page
Anthracite Grey UPVC 1.5m x 9mm(2 Pack)Capping Board – Depth Options: 150mm to 300mm
In stock
£34.28 – £59.37 (Vat inc.)
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This product has multiple variants. The options may be chosen on the product page
Anthracite Grey UPVC 1.5m x 9mm(4 Pack)Capping Board – Depth Options: 150mm to 300mm
In stock
£68.57 – £118.74 (Vat inc.)
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This product has multiple variants. The options may be chosen on the product page
Anthracite Grey UPVC 1.75m x 9mm Capping Board – Depth Options: 150mm to 300mm
In stock
£23.47 – £40.65 (Vat inc.)
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This product has multiple variants. The options may be chosen on the product page
Anthracite Grey UPVC 1.75m x 9mm(2 Pack)Capping Board – Depth Options: 150mm to 300mm
In stock
£35.21 – £60.97 (Vat inc.)
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This product has multiple variants. The options may be chosen on the product page
Anthracite Grey UPVC 1.75m x 9mm(4 Pack)Capping Board – Depth Options: 150mm to 300mm
In stock
£70.42 – £121.95 (Vat inc.)
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This product has multiple variants. The options may be chosen on the product page
Anthracite Grey UPVC 2m x 9mm Capping Board – Depth Options: 150mm to 300mm
In stock
£24.71 – £42.79 (Vat inc.)
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This product has multiple variants. The options may be chosen on the product page
Anthracite Grey UPVC 2m x 9mm(2 Pack)Capping Board – Depth Options: 150mm to 300mm
In stock
£37.06 – £64.18 (Vat inc.)
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This product has multiple variants. The options may be chosen on the product page
Anthracite Grey UPVC 2m x 9mm(4 Pack)Capping Board – Depth Options: 150mm to 300mm
In stock
£74.13 – £128.37 (Vat inc.)
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This product has multiple variants. The options may be chosen on the product page
Anthracite Grey UPVC 3m x 9mm Capping Board – Depth Options: 150mm to 300mm
In stock
£52.18 – £72.07 (Vat inc.)
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This product has multiple variants. The options may be chosen on the product page
Anthracite Grey UPVC 3m x 9mm(2 Pack)Capping Board – Depth Options: 150mm to 300mm
In stock
£65.77 – £95.60 (Vat inc.)
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This product has multiple variants. The options may be chosen on the product page
Anthracite Grey UPVC 3m x 9mm(4 Pack)Capping Board – Depth Options: 150mm to 300mm
In stock
£106.54 – £166.21 (Vat inc.)
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This product has multiple variants. The options may be chosen on the product page
Black Ash UPVC 1.25m x 9mm Capping Board – Depth Options: 150mm to 300mm
In stock
£22.24 – £38.51 (Vat inc.)
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This product has multiple variants. The options may be chosen on the product page
Black Ash UPVC 1.25m x 9mm(2 Pack)Capping Board – Depth Options: 150mm to 300mm
In stock
£33.35 – £57.76 (Vat inc.)
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This product has multiple variants. The options may be chosen on the product page
Black Ash UPVC 1.25m x 9mm(4 Pack)Capping Board – Depth Options: 150mm to 300mm
In stock
£66.72 – £115.53 (Vat inc.)
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This product has multiple variants. The options may be chosen on the product page
Abundant Offer for Individual and Business Clients!
We are dedicated to creating the most efficient solutions and offering a wide selection of products for people eager to build the home of their dreams!
With our extensive range of products, you can choose not only the type of doors, windows, or other items but also personalize them to suit your needs. With Windows4You, you are in charge!
Changing the color? No problem! Adjusting the size? Piece of cake!
Now, you can design your home on your own terms!
If you encounter any issues with installation, you can count on us. With 11 years of experience as windows and doors installers, we ensure professional support every step of the way.
We are also open to partnerships in the B2B sector. Learn more about our B2B offer here:
https://www.window4you.co.uk/trade
Window sills