What are Blown Windows and How Would They Affect a Property Purchase

Blown windows are a common issue in homes with double glazing, occurring when the seal between the glass panes fails. This allows moisture to seep in, creating a cloudy or foggy appearance that can obscure the view and reduce energy efficiency.

Blown windows can significantly impact a property purchase, potentially lowering the home’s value and increasing future maintenance costs.

When considering a property purchase, it’s crucial to inspect the windows for signs of seal failure.

Condensation between the panes, a milky or misty appearance, or water droplets inside the glass are telltale indicators of blown windows.

These issues not only affect the aesthetics of a home but can also lead to increased energy bills and potential damage to window frames or surrounding walls if left unaddressed.

Prospective buyers should factor in the cost of repairing or replacing blown windows when negotiating a property’s price. Depending on the size and number of affected windows, repairs can range from £100 to £850 per window.

For older properties with multiple blown windows, this could represent a substantial additional expense that should be carefully considered before finalising a purchase.

Understanding Blown Windows

Blown windows are a common issue in double-glazed units that can impact a property’s energy efficiency and aesthetics. This problem occurs when the seal between the glass panes fails, allowing moisture to enter the cavity.

Defining a Blown Window

A blown window refers to a double-glazed unit where the airtight seal has failed. This failure allows moisture to penetrate the space between the two panes of glass.

The result is a foggy or misty appearance that can obstruct visibility and reduce the window’s insulating properties.

Signs of a blown window include:

• Condensation between the glass panes
• A milky or cloudy appearance
• Water droplets inside the unit
• Streaks or smears that cannot be cleaned from the outside

These symptoms typically worsen in cold weather or when there’s a significant temperature difference between indoors and outdoors.

Causes of Window Seal Failures

Several factors can contribute to the breakdown of window seals:

1. Age: Over time, seals naturally degrade and lose their effectiveness.
2. Temperature fluctuations: Extreme changes can cause the glass and frame to expand and contract, stressing the seal.
3. Poor installation: Improper fitting can lead to premature seal failure.
4. Manufacturing defects: Substandard materials or production processes may result in weak seals.

Exposure to direct sunlight, high humidity, and physical damage can also accelerate seal deterioration.

Regular maintenance and prompt repairs can help extend the life of double-glazed units and prevent blown windows.

Impact on Insulation and Energy Efficiency

Blown windows significantly affect a property’s thermal performance and energy consumption. The compromised structure leads to heat loss and increased utility costs, impacting both comfort and finances.

Deterioration of Insulating Properties

Blown windows lose their insulating capabilities due to damaged seals. Double-glazed windows rely on an inert gas, typically argon, trapped between panes to slow heat transfer.

When seals fail, this gas escapes, reducing the window’s insulating effectiveness.

The gap between panes may fill with moisture, further degrading insulation. This can lead to condensation and mould growth, exacerbating energy efficiency issues.

Blown windows essentially revert to single-pane performance, allowing heat to escape more readily in winter and enter during summer.

Consequences for Heating Bills and Energy Use

The loss of insulation from blown windows directly impacts energy consumption and costs.

Properties with compromised windows often see a marked increase in heating bills as systems work harder to maintain comfortable temperatures.

In winter, heat escapes more quickly, forcing heating systems to run longer and more frequently. Summer cooling costs may also rise as warm air penetrates more easily. This reduced energy efficiency can significantly impact a home’s overall performance rating.

Replacing blown windows with A-rated energy-efficient glass can lead to substantial savings.

Modern double or triple-glazed units offer superior insulation, potentially cutting energy bills by 10-15% annually. They also enhance comfort by maintaining more consistent indoor temperatures.

Identifying Symptoms of Blown Double Glazing

Recognising the signs of blown double glazing is crucial for homeowners and property buyers alike. The telltale indicators can be both visual and physical, often affecting the window’s appearance and performance.

Visual Signs of Blown Windows

Misted double glazing is a primary visual symptom of blown windows. Look for foggy or misty patches between the glass panes, which may appear as small droplets or larger cloudy areas. These patches can vary in size and may grow over time.

In some cases, the condensation might form intricate patterns or streaks on the inside of the glass unit. Pay close attention to the edges of the window, as this is where moisture often first penetrates the seal.

Changes in the window’s appearance during different weather conditions can also indicate blown double glazing. The misting might become more pronounced on cold days or disappear temporarily in warmer weather.

Physical Symptoms and Draught Detection

Blown double glazed windows often lead to decreased insulation performance. Check for cold spots on the glass surface or around the window frame, which may indicate compromised thermal efficiency.

Draughts are another key indicator of blown windows. Run your hand along the edges of the window to feel for air movement. A lit candle held near the window can also help detect subtle air currents.

Increased external noise penetration might suggest that the window’s soundproofing capabilities have been compromised due to seal failure. Listen for changes in ambient noise levels when near the affected windows.

Dampness around the window frame or on nearby walls can be a sign of blown double glazing allowing moisture to penetrate. Look for peeling paint, mould growth, or water stains in the surrounding areas.

Effects on Comfort and Property Value

Blown windows can significantly impact a property’s liveability and market appeal. These issues extend beyond mere aesthetics, affecting the daily comfort of occupants and the overall value of a home.

Dealing with Noise and Draught Problems

Blown windows often lead to increased noise pollution and persistent draughts. As the seal between panes deteriorates, outside sounds penetrate more easily, disrupting the peace within.

Cold air seeps through compromised seals, creating uncomfortable draughts and chilly spots near windows. This can result in higher heating costs as occupants attempt to maintain a comfortable temperature.

Moisture intrusion is another concern. Blown windows may allow water to seep in during rainy weather, potentially leading to damp problems. This excess moisture can damage internal decorations, causing discoloured walls and peeling wallpaper.

In severe cases, it may even contribute to the growth of mould, posing health risks to occupants.

Impact on Property Marketability and Purchase Decisions

Blown windows can significantly affect a property’s marketability and influence potential buyers’ decisions.

Visible condensation between panes is an immediate red flag during viewings. This obvious defect can make prospective purchasers wary, as it signals potential underlying issues and future repair costs.

Properties with blown windows often fetch lower offers, as buyers factor in the expense of window replacements. Estate agents may struggle to present the home in its best light, potentially leading to longer listing times.

For sellers, addressing blown windows before listing can be a wise investment, potentially increasing the property’s appeal and final sale price.

Options for Remediation and Repair

Addressing blown windows involves deciding between repair and replacement. The choice depends on factors like window condition, age, and budget. Misted window repair offers a cost-effective solution for certain cases.

Choosing Between Repair or Replacement

Repair is often suitable for minor issues or newer windows. It’s typically less expensive and quicker than full replacement. Window repair costs range from £50 to £200 per unit, depending on size and complexity.

Replacement becomes necessary for severely damaged or outdated windows. While pricier, it offers improved energy efficiency and aesthetics. New double-glazed windows cost £200 to £850 per unit, varying by size and quality.

Consider the window’s age and overall condition. If other components are deteriorating, replacement might be more cost-effective long-term. Consult a professional to assess the best option for your specific situation.

Misted Window Repair Processes

Misted window repair targets the issue of condensation between panes. The process involves drilling small holes in the glass to remove moisture and insert a drying agent.

A specialist then seals the unit, restoring clarity and insulation. This method is less disruptive and more affordable than full replacement.

Key steps in misted window repair:

1. Inspection and assessment
2. Drilling access holes
3. Moisture removal
4. Insertion of drying agent
5. Resealing the unit

Success rates are high, but not guaranteed for all cases. The repair typically takes a few hours per window. Costs range from £50 to £150 per unit, depending on size and accessibility.

Preventive Measures and Regular Maintenance

Proper care and upkeep of windows can significantly extend their lifespan and prevent issues like blown double glazing. Regular inspections and using high-quality materials are crucial for maintaining window integrity.

Best Practices for Prolonging Window Life

Conduct visual inspections of windows every 6 months. Check for signs of seal failure, such as condensation between panes. Clean window frames and tracks regularly to prevent dirt buildup. Lubricate moving parts annually with silicone spray.

Ensure proper ventilation to reduce moisture levels. Use extractor fans in bathrooms and kitchens. Open windows periodically to allow air circulation, especially in colder months.

Address any issues promptly. Small cracks or chips in glass should be repaired immediately. Replace damaged weather stripping or seals to maintain energy efficiency.

Consider professional servicing every 2-3 years. Experts can spot potential problems early and perform necessary maintenance.

Importance of Using Quality Materials

Invest in high-quality double glazing units from reputable manufacturers. Superior materials resist seal failure and provide better insulation.

Opt for toughened or laminated glass for enhanced durability and security. These types are less prone to breakage from impacts or temperature fluctuations.

Choose frames made from robust materials like uPVC, aluminium, or hardwood. These offer better resistance to weathering and require less maintenance.

Ensure proper installation by qualified professionals. Correct fitting is crucial for preventing air and moisture infiltration, which can lead to seal failure.

Use high-grade sealants and gaskets designed for window applications. These components play a vital role in maintaining the integrity of double glazing units.