A draught around a roof window can affect more than the comfort of the room below. Uncontrolled air leakage can contribute to heat loss, colder internal surfaces, and reduced energy efficiency, making it an important issue for property developers, landlords, and installers to identify and resolve.
If you’re wondering why there is a draught coming through your window, the first step is to establish where the air is entering. While some draughts can be resolved with straightforward maintenance, others can point to problems with the original installation or an ageing roof window that no longer provides the required thermal performance.
This guide looks at what causes draughts around roof windows, how to identify the source and the practical steps professionals can take to address the problem.
There is no single cause of a draughty roof window. The issue can originate from the window itself, the surrounding installation, or the wider roof construction, so it is important to inspect the complete system before deciding on the appropriate repair.
Seals create a close connection between the opening sash and window frame, helping to prevent uncontrolled air leakage when the window is closed. With age and regular use, these seals can become worn, damaged or compressed. Even relatively small areas of deterioration can create a noticeable draught, particularly during colder or windy weather.
If the frame, glazing, and other components remain in good condition, replacing the affected seals may be enough to improve airtightness without replacing the complete window.
Even a high-performance roof window can become draughty if it has not been installed correctly. Gaps between the frame and roof structure, insufficient insulation, or poorly detailed junctions can all create pathways for cold air.
This means installers should look beyond the window itself when investigating a draught. If the seals appear intact, the surrounding insulation and installation details should be checked for gaps or areas where the thermal envelope has been interrupted. Following the appropriate installation guidance can help ensure roof windows achieve their intended performance.
Flashing provides the weather-resistant connection between the roof window and surrounding roofing material. If it is damaged, displaced, or incorrectly installed, the overall performance of the roof window installation can be compromised.
During an inspection, check the condition of the flashing and its connection with the surrounding roof covering. It is also important to confirm that the correct flashing solution has been specified for the roofing material and window installation.
Older roof windows can experience deterioration across several components at the same time. Seals may become less effective, frames can deteriorate and older glazing systems may provide lower thermal performance than modern alternatives.
Where repeated maintenance is required or draughts continue alongside condensation, cold spots, or excessive heat loss, replacing an ageing window may provide a more effective long-term solution than continuing with individual repairs.
For guidance on choosing the right roof window replacement, check out our useful guide.
Before deciding how to draught proof a window, establish whether the issue originates from the opening window, frame, or surrounding installation. On a cold or windy day, check around the closed window for noticeable air movement, paying particular attention to the sash, seals, and junction between the frame and internal finish.
Cold spots can provide another indication. If one area of the frame or reveal feels noticeably colder than the surrounding surfaces, this may suggest insufficient insulation, thermal bridging, or an installation gap rather than a problem with the window itself.
Condensation can also indicate a wider thermal performance issue, as condensation can be caused by draughty windows. Air leakage itself is not the only cause, but poor insulation and cold surfaces around a roof window can contribute to the conditions in which condensation develops. Warm, moisture-containing indoor air meeting a cold surface can result in condensation, so ventilation, humidity, and insulation should all be considered when diagnosing the problem. Find out more in our guide to mould in loft spaces.
Once the source of the draught has been identified, repairs for how to draught proof a window should address the underlying problem rather than simply covering visible gaps.
Start by checking the seals around the sash and frame for cracks, gaps, compression, or other signs of deterioration. If a seal is damaged but the rest of the window remains sound, replacing the appropriate component may be sufficient to restore a tighter connection.
The flashing and surrounding installation should then be inspected. Check for damaged or displaced flashing, gaps around the frame, and poorly finished junctions. Any repair should maintain the correct weatherproofing and ventilation requirements of the roof window rather than relying on additional sealant as a temporary fix.
Insulation around the reveal is equally important. Gaps or poorly fitted insulation can create thermal bridges and noticeable cold areas even when the roof window itself is performing correctly. Improving insulation continuity around the frame can therefore help reduce cold spots and unwanted heat loss.
For more information on the wider impact of insulation and airtightness, read our guide to preventing heat loss through the roof.
Not every draughty roof window needs to be replaced. If the window is relatively modern, structurally sound, and the problem can be traced to a worn seal, flashing issue or correctable installation detail, repair is likely to be the most practical approach.
Replacement becomes more relevant when an older unit experiences persistent draughts, condensation or poor thermal performance despite previous repairs. This is particularly important during retrofit projects where insulation and airtightness elsewhere in the roof are being improved. Retaining an ageing, inefficient roof window can leave a weaker point within an otherwise upgraded thermal envelope.
Replacing an older unit with a modern pitched roof window provides an opportunity to improve glazing performance, airtightness and overall energy efficiency. For non-habitable areas such as storage lofts and roof voids, Dakea skylights offer a practical alternative where daylight and ventilation are required.
Dakea provides roof window solutions designed for professional installation across retrofit, refurbishment, and new-build projects. Our range of roof windows includes energy-efficient options designed to support improved thermal performance and comfort in habitable spaces.
When correctly specified and installed alongside effective insulation and airtight detailing, Dakea roof windows can help reduce unwanted heat loss and provide a reliable long-term replacement for ageing or poorly performing units. For non-habitable roof spaces, our skylights provide practical solutions where ventilation, daylight and roof access are required.
With straightforward installation, technical support, low lead times and guarantees of up to 20 years on registered pitched roof windows, Dakea provides dependable solutions for installers, developers and property professionals.
Explore our pitched roof windows or get in touch for support finding the right solution for your next project.
Are you a professional installer, contractor, or housebuilder? Sign up for our newsletter today to be the first to hear about new products, promotions and exclusive offers.
For all other enquiries please complete our contact form
on our website.