As temperatures drop and the North East weather turns damp, many homeowners start to notice unwelcome signs. Cold draughts, misted panes, or damp patches around the window frame. What may seem like a small problem can quickly lead to heat loss, higher energy bills, and even mould or structural damage if left unchecked.
Leaking double-glazed windows are usually a sign of failing seals or ageing units. Over time, the airtight barrier that keeps warm air in and moisture out can weaken, allowing air or water to enter your home. It’s a common issue in properties across Middlesbrough, Teesside, and the wider North East, especially after years of exposure to rain, wind, and changing temperatures.
In this guide, we’ll explain what causes leaking windows, the warning signs to look for, and what you can do to fix or replace them before winter sets in.
What Causes Leaking Double Glazed Windows?
Many homeowners discover leaking double-glazed windows as the seasons change. It can happen to any home, old or new. Leaks can mean two things – air ingress (draughts) or water ingress (moisture getting in). Both reduce comfort, increase energy waste, and may damage your home.
What Does a “Leaking Window” Really Mean?
When a double-glazed window leaks, air or water passes through areas that should be sealed. Double glazing contains two panes of glass separated by an insulating gap, often filled with argon gas.
If that seal weakens, cold air and moisture can enter. You may feel draughts or see condensation that never wipes away. Fortunately, these issues are common and usually easy to fix with professional help.
Perished or Damaged Window Seals
Over time, rubber or silicone seals around your window lose flexibility. Constant exposure to sunlight, rain, and temperature changes breaks them down. When this happens, air and moisture can move freely between the glass panes or around the frame. If you notice condensation or cold air near your windows, the seals may need replacing. This is one of the simplest and most effective fixes.
Failed or “Blown” Double Glazing Units
A blown double-glazed window happens when the sealed unit loses its airtight bond. The argon gas fill escapes, and air takes its place. This allows moisture to collect between the panes, causing misting or fogging that can’t be cleaned. Once this happens, the unit’s insulation value drops. Replacing the sealed unit (not always the whole frame) restores performance and prevents further heat loss.
Blocked Drainage Channels and Weep Holes
Modern uPVC and aluminium windows include small weep holes or drainage channels that let water escape. If these become blocked by dirt, dust, or paint, trapped moisture can seep inside.
During heavy North East rain, that trapped water can cause damp sills, swollen wood, or mould growth. Cleaning these drainage points once or twice a year helps prevent water ingress.
Poor Installation or Frame Warping
Sometimes the issue starts with poor fitting. If a window wasn’t installed level or sealed correctly, gaps may form around the edges. Frame warping can also occur over time, especially in older timber or uPVC units.
Expansion and contraction from heat or cold gradually affect alignment. These gaps allow both air and water to enter, creating draughts and reducing energy efficiency. In many cases, a professional can re-align or re-seal the frame to resolve it.
Age and Material Degradation
Most double-glazed windows last 20 to 25 years before performance declines. Over decades, constant weather exposure causes hinges, seals, and frames to weaken.
Older uPVC or timber windows often lose insulation quality, leading to higher U-values and noticeable draughts. Replacing them with modern A-rated glazing can instantly improve warmth, comfort, and energy efficiency.
Why Window Leaks Are Common in the North East
Homes in Middlesbrough, Teesside, and across the North East face a challenging climate. Frequent rain, salt air, and strong coastal winds wear down seals faster. That’s why many local homeowners experience leaking or draughty windows, especially during autumn and winter.
At Celestial Windows, we design and manufacture products specifically for these regional conditions – strong, weather-resistant, and built to last.
Signs Your Double Glazing Is Leaking Air or Water
Leaking double-glazed windows don’t always show obvious damage at first. However, there are several easy-to-spot warning signs that indicate air or water ingress. Catching them early can save money and protect your home from lasting damage.
Here are the most common signs of leaking double glazing:
- Condensation or misting between glass panes – If the fog sits between the panes and can’t be wiped away, your sealed unit has failed.
- Damp or mould around window frames – Moisture seeping through damaged seals or blocked drainage can lead to black mould growth.
- Peeling paint or swollen sills – Signs of trapped water, especially near timber or plaster surfaces.
- Feeling a chill or draught even when windows are closed – A clear sign of air leakage through perished seals or warped frames.
- Higher heating bills without clear reason – Escaping heat makes your boiler or heating system work harder.
If you’ve noticed one or more of these symptoms, your windows may need attention soon. Acting early prevents moisture damage, helps maintain your home’s warmth, and reduces long-term repair costs.
Is It Dangerous to Ignore a Leak?
Yes – ignoring leaking double-glazed windows can cause serious long-term damage. Even small leaks allow water or cold air to enter, creating problems that worsen over time.
Here’s what can happen if a window leak is left untreated:
- Structural damp and rot – Water seeps into plaster, wood, and insulation, weakening walls and sills.
- Mould growth – Persistent moisture creates ideal conditions for black mould, which can trigger allergies and respiratory problems.
- Rising energy bills – Escaping warm air forces your heating to run longer and waste energy.
- Ruined décor – Peeling paint, warped skirting boards, and damp patches often appear around frames.
A quick repair or replacement prevents these issues and protects both your comfort and property value. If you suspect a leak, arrange an inspection as soon as possible to stop further damage.
Can Leaking Double Glazed Windows Be Repaired?
Yes – in many cases, leaking double-glazed windows can be repaired rather than replaced. The solution depends on the cause and extent of the problem.
If the issue is minor, such as worn or split seals, a straightforward replacement can quickly restore the airtight barrier. Sometimes, blocked drainage channels or weep holes are the culprit. When cleared, they allow trapped rainwater to escape properly, preventing further leaks. In other cases, a small hinge or lock adjustment is all that’s needed to tighten the frame and stop draughts.
However, if you notice condensation or misting between the panes, this suggests the sealed unit has failed. Once that happens, the insulating gas escapes and moisture seeps in, reducing thermal efficiency. The glass unit, known as an Insulated Glass Unit (IGU), will need replacing.
When Replacement Is the Best Option
Sometimes, repairs offer only a temporary fix. If your windows have severe misting, persistent draughts, or damaged frames, full replacement may be the best long-term solution. Windows older than twenty years often struggle to meet modern energy standards, allowing heat to escape even after small repairs.
Upgrading to A-rated double or triple glazing delivers lasting comfort and efficiency. New windows significantly improve insulation, reduce noise, and refresh your home’s appearance. Over time, these benefits can lower heating costs and increase your property’s value.
Every product from Celestial Windows is manufactured locally in Middlesbrough and installed by our FENSA-certified fitters. We take pride in providing clean, efficient installations backed by a solid warranty – ensuring your home stays warm, dry, and energy-efficient for years to come.
How Celestial Windows Can Help You Fix Leaking Double Glazed Windows
Leaking Windows Are Common – and Fixable
If your double-glazed windows are leaking, you’re not alone. It’s one of the most common issues faced by homeowners across Middlesbrough, Teesside, and the North East – especially as colder, wetter weather arrives.
Most leaks happen because of worn seals (especially in casement windows), blocked drainage channels, or ageing window frames. Left untreated, they can lead to damp patches, mould growth, and higher heating bills. The good news is that these problems are entirely fixable. Acting early can prevent long-term damage and keep your home warm and energy-efficient all winter.
The Celestial Windows Difference
At Celestial Windows, we understand how frustrating a leaking or misted window can be – and how important it is to put it right quickly. Our team provides a complete, local service, handling everything from free inspections and repairs to full replacement installations.
Every window and door we supply is manufactured locally in Middlesbrough, built to withstand the North East’s tough weather. We use A-rated glazing for maximum energy efficiency and long-lasting performance. All our installers are FENSA-certified, so you can trust that every job meets the highest standards of safety and quality.
What sets us apart is our honest approach. We’ll never recommend new windows if a simple repair will do. Our goal is to give you clear advice, great value, and complete peace of mind – ensuring your home stays warm, dry, and comfortable all year round.
Book Your Free Inspection Today
If you’ve noticed draughts, condensation, or signs of water around your windows, now is the perfect time to act. A quick inspection today could save you from costly repairs later.
Book your free, no-obligation quote with Celestial Windows and let our experts find the best solution for your home. Whether it’s a simple seal replacement or a full window upgrade, we’ll handle everything with care, precision, and professionalism.
Call our Middlesbrough team or get in touch online to arrange your visit. With Celestial Windows, fixing your leaking double glazing is simple, affordable, and stress-free – so you can enjoy a warmer, quieter home this winter and beyond.
