How to draught-proof your timber sash windows
As the colder months set in, keeping your home warm and energy-efficient becomes all the more important. Timber sash windows are a beautiful and characterful feature in many properties. However, they are also a common source of unwanted draughts. Left untreated, they can let in cold air, increase energy consumption, and drive up heating costs.
The good news is that effective draught-proofing can help you enjoy the charm of your sash windows without compromising on comfort. In this guide, we’ll take you through practical steps to reduce draughts, improve insulation, and maintain a cosier, more efficient home throughout the year.
Beyond warmth and comfort, draught-proofing your timber sash windows offers long-term benefits. By preventing unnecessary heat loss, you’ll lower your energy bills and reduce your carbon footprint. A well-sealed window also helps to keep out dust, pollen, and external noise, creating a healthier, quieter living environment for you and your family.
What You’ll Need
To draught-proof sash windows effectively, you’ll need a few simple materials and tools:
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Draught excluder strips – Available in foam, rubber, or brush form, these strips are designed to create a discreet but effective seal along the edges of your sashes. Reddipile
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Weatherstripping – Ideal for sealing the meeting rail where the two sashes overlap, or other moving joints that are prone to gaps. Weather Seals
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Sealant – A flexible, good-quality sealant is perfect for filling fine cracks in the timber frame or around the edges of the window. Sealants
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Paint and brushes – Once repairs and sealing are complete, a fresh coat of paint will help protect the timber from future damage.
Step-by-Step Guide to Draught-Proofing Sash Windows
Draught-proofing sash windows can be a tricky task and often requires the expertise of a specialist. Standard seals won’t do the job – you’ll need products specifically designed for sash windows, such as Reddipile Weatherstrip. While it may take extra effort, properly draught-proofing your sash windows can make a noticeable difference, helping you cut down on heating costs during the colder months.
- Inspect your windows thoroughly
Begin by examining your sash windows in good light. Look for common trouble spots such as gaps around the sash box, cracks in the timber, or a loose fit where the two sashes meet. Noting these issues first will help you target your efforts effectively. - Clean and prepare the surfaces
Before adding any draught-proofing materials, clean the timber and glass. Use a soft cloth with a mild detergent to remove dust, grease, and grime. Clean surfaces ensure that strips and sealant bond properly. - Fit draught excluder strips
Measure the sides and top of your sash window, then cut the strips to length. Apply them carefully along the edges where the sash meets the frame. A well-fitted strip should create a snug seal while still allowing the sash to glide smoothly. - Apply weatherstripping to moving joints
Focus on the meeting rail where the upper and lower sashes overlap. This is a prime source of draughts. Weatherstripping here prevents cold air from sneaking in while allowing you to continue opening and closing the window without resistance. - Seal any remaining gaps
If you find fine cracks in the frame or small openings that strips can’t cover, apply a bead of flexible sealant. Smooth it with a damp cloth or tool for a neat finish. Allow it to dry fully before painting. - Finish with a protective coat of paint
Once the sealant is set, give your sash frames a fresh coat of exterior-grade paint. This not only refreshes their appearance but also protects the timber against moisture and rot, prolonging the lifespan of your windows. - Test functionality
Finally, open and close your windows to make sure everything works smoothly. If you notice any sticking, lightly trim back excess material until you achieve the perfect balance of insulation and usability.
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Further Tips
- Painting over seals
Be cautious when painting around fitted seals. Depending on the type, painting over them can cause blockages that stop them from expanding and sealing as intended. The good news is that many modern seals are designed to withstand paints and stains, giving you flexibility without compromising performance. - Ventilation
While draught-proofing is important for energy efficiency, it’s equally essential to maintain proper ventilation. Poor airflow can lead to condensation, mould, and damp over time. A practical way to balance warmth with ventilation is to install trickle vents above your windows, which help reduce condensation while keeping heat indoors.
See our full range of sash window draught proofing products
At Reddiseals, we’ve got everything you’ll need to draught proof sash windows. Take a look at our window seals and door seals selection before starting. If you need any further help and advice on any of our products, please call us on 01905 791876!
