Draughts and air infiltration: Why It Matters, and How to Fix It
Few things undermine the enjoyment of new windows more quickly than discovering an unexpected draught. In our experience, concerns about draughts and air infiltration are probably the most common issue reported by homeowners after replacement glazing has been installed. It can be genuinely worrying: you have invested in a product intended to improve comfort and thermal performance, yet certain rooms still feel cold, “draughty”, or difficult to heat.
The key point is simple. If you can feel a draught, air is moving either through the window assembly or around it. Determining which of these is happening is the first step to identifying the underlying cause and, crucially, the correct remedy.
Why draughts matter more than most people think
Thermal performance is the number one reason many people replace windows. It is not just about glass U-values or energy labels—it is about real-world comfort: eliminating cold spots, reducing heat loss, and creating more stable internal temperatures.
Even a small amount of uncontrolled air leakage can have a disproportionate impact. When cold external air enters the home, it does not simply “sit” by the window; it mixes with warmer internal air and encourages convection currents. The movement of air around a home is a complicated matter—warm air rises, cooler air drops, pressure differences develop between rooms and floors, and wind can drive infiltration more forcefully on exposed elevations. The result can be persistent discomfort, draught sensation, and higher heating demand at a time when energy costs remain a major household concern.
In short: a window can be made from excellent components and still perform poorly if air leakage pathways exist.
Draughts from around the window: typically installation and sealing issues
If the draught is coming around the perimeter of the window—between the frame and the surrounding wall—this is generally an installation issue. The installation should provide a continuous, effective seal between the window frame and the property, preventing external air from bypassing the window’s designed weather seals.
Sometimes the problem is obvious: visible gaps, incomplete sealant lines, or poorly finished perimeter details. More often, the issue is subtle. Air leakage can occur through small discontinuities that are difficult to spot visually but can have a significant effect on comfort.
Common contributors include:
- Incomplete or poorly bonded perimeter sealing (for example, sealant that has not adhered properly to one surface, or has been applied over dust/contamination).
- Voids behind trims where cosmetic finishing hides gaps rather than sealing them.
- Discontinuity in the air seal at corners, at junctions with sills, or where different materials meet.
- Substrate irregularities (uneven masonry, damaged reveals, or poorly prepared openings) that make achieving a continuous seal more challenging.
- Movement and shrinkage over time, particularly if inappropriate materials have been used or detailing does not accommodate minor building movement.
The important distinction here is that draughts “around” the window are not usually resolved by adjusting hinges or locks. The solution is typically to address the continuity and quality of the perimeter sealing and installation detailing.
Draughts from through the window: alignment, compression, and hardware performance
If the draught is coming through the window—through opening sashes, meeting rails, or gasket lines—this is more commonly related to alignment and compression in the opening sections.
Modern windows rely on controlled compression between the sash and frame (or leaf and frame) so that gaskets and weather seals can do their job. If that compression is reduced, air can pass the seals even if everything looks “closed”.
Air infiltration through the window can arise from multiple causes, including:
- Poor frame alignment (the installed frame may be twisted, racked, or bowed, preventing uniform seal contact).
- Sash/leaf misalignment (hinge geometry, toe-and-heeling issues, or general set-up problems can prevent correct closing engagement).
- Incorrect glass unit packing (the IGU packers support the sealed unit and help maintain correct sash geometry; incorrect packing can lead to drop, twist, or poor gasket contact).
- Locking mechanism adjustment (cams, keeps, and shoot bolts may require correct adjustment to draw the sash evenly into the seals).
- Seal or gasket issues (damaged, displaced, incorrectly fitted, or unsuitable seals; occasionally, manufacturing or specification issues can contribute).
The challenge is that several of these factors can present in similar ways to the occupants —“it feels draughty”—but the remedies are different. Adjusting locks may help in some cases, but if the root cause is frame distortion or incorrect packing, adjustments alone may not provide a durable fix.
Diagnosing the cause takes time and expertise
The uncomfortable truth is that correctly diagnosing draughts and air infiltration is rarely a one-minute job. Air can enter at one point, travel within cavities or behind trims, and be felt somewhere else entirely. Wind direction, external exposure, internal pressure differences, and even extractor fans can influence where and when draughts are most noticeable.
A reliable diagnosis typically requires:
- A methodical inspection of installation detailing and perimeter sealing continuity.
- Assessment of frame position, alignment, and fixings relative to the opening.
- Examination of opening light geometry, gasket engagement, and operational behaviour.
- Review of glass unit packing where accessible/appropriate.
- Evaluation of hardware set-up and adjustments, including locking engagement and compression.
This is precisely where independent technical assessment adds value: rather than trial-and-error fixes, you get a structured understanding of what is happening and why.
How RISA can help
The good news is that draught problems are often resolvable once the true cause is identified. RISA’s team of highly trained and experienced Assessors are there to help homeowners, Installers and other stakeholders get to the bottom of air infiltration issues.
Our in-depth inspections focus on both sides of the equation:
- Through the window: alignment, compression, sealing interfaces, locking engagement, and product performance in real conditions.
- Around the window: installation good practice, perimeter sealing continuity, interface detailing, and evidence of air leakage pathways.
Because we work across different product types and installation methods, we can quickly identify likely failure mechanisms and advise on the most appropriate resolution—whether that involves targeted adjustment, corrective packing, remedial sealing, or more substantial rectification where necessary.
Practical homeowner pointers: what to observe before an inspection
If you suspect draughts, it can help to note a few observations (without jumping to conclusions):
- Does the draught feel strongest at the perimeter (wall/frame junction) or at the opening edges (gasket lines)?
- Is it worse in windy conditions, or consistent regardless of weather?
- Does it change when internal doors are opened/closed, or when extractor fans run?
- Are there any visible gaps externally or internally, particularly at corners and sill junctions?
- Do the openings feel “even” when closing, or is there a point where the handle becomes unusually tight/loose?
These details can support a faster, more accurate diagnosis.
Final thoughts
Draughts should not be dismissed as “just one of those things”. When windows are replaced for thermal performance and comfort, any air infiltration is rightly frustrating—and in many cases it is avoidable. Whether the air is coming through the window due to poor compression or alignment, or around it due to incomplete sealing and installation detailing, the solution starts with a proper technical assessment.
If you are experiencing draughts or suspect air leakage around new windows, RISA can help identify the cause and advise on the correct next steps—saving time, reducing disruption, and restoring the comfort you expected from your investment.