Retrofitting double glazing into existing windows is an excellent way to improve insulation, reduce noise, and enhance energy efficiency without replacing your entire window frames. This approach is ideal for homeowners looking to upgrade their property without compromising the original style or investing in full window replacement. By understanding the steps, materials, and benefits involved, you can make informed decisions about retrofitting double glazing to suit your needs and budget.
Understanding Retrofit Double Glazing
What Is Retrofit Double Glazing?
Retrofit double glazing involves installing an additional pane of glass or a sealed double-glazed unit into an existing window frame. Unlike traditional double glazing, which is fitted during window manufacturing, retrofitting allows you to retain your original frames making it a more cost-effective and less intrusive upgrade.
Why Choose Retrofitting Over Replacement?
- Cost-saving: No need to replace entire window frames
- Preserve aesthetics: Ideal for heritage homes or period properties
- Less disruption: Faster installation with minimal mess
- Eco-friendly: Reusing existing materials reduces waste
Benefits of Retrofit Double Glazing
Improved Thermal Insulation
Double glazed units significantly reduce heat loss through windows. The air or gas-filled gap between the panes acts as a thermal barrier, helping your home stay warmer in winter and cooler in summer.
Enhanced Soundproofing
If you live near a busy road or in a noisy neighborhood, retrofitting double glazing helps dampen sound by adding a second layer of glass and an insulating gap.
Increased Property Value
Improving energy efficiency and comfort can make your home more attractive to buyers, adding long-term value to your investment.
Types of Retrofit Double Glazing Systems
Secondary Glazing
Secondary glazing involves adding a second pane of glass inside the existing window. It’s often removable, making it ideal for rental properties or listed buildings where changes to the original windows are restricted.
Replacement Glass Units
Another option is to replace the existing single pane with a sealed double-glazed unit that fits within the original frame. This approach provides better insulation and aesthetics but may require some frame modification.
Step-by-Step Guide to Retrofit Double Glazing
Step 1: Evaluate Your Existing Windows
Inspect your current window frames to determine if they are structurally sound. Timber, aluminum, and uPVC frames can all be retrofitted, but the condition and size of the frames will affect your options.
Step 2: Choose the Right Retrofit System
Decide between secondary glazing or full double-glazed units. Consider factors such as budget, appearance, and the level of insulation or soundproofing you want to achieve.
Step 3: Measure the Windows Accurately
Careful measurement is essential for ensuring a proper fit. Measure the height, width, and depth of the existing window recess. If unsure, consult a professional glazier for help.
Step 4: Remove the Existing Glass (If Necessary)
If you are replacing the glass rather than adding a secondary layer, carefully remove the existing pane. This step requires precision and safety equipment such as gloves and protective glasses.
Step 5: Prepare the Frame
Clean and sand the frame, ensuring it’s free of dirt and old sealant. Any damage or rot should be repaired before proceeding. A well-prepared surface ensures a secure and airtight fit.
Step 6: Install the Double Glazed Unit or Secondary Glazing
- For secondary glazing: Attach the additional panel using clips or magnetic strips, depending on the design. Some systems slide or are hinged for easy access.
- For sealed units: Fit the new double-glazed panel into the prepared frame, apply glazing tape or sealant, and secure it with beading.
Step 7: Seal and Finish
Use weather-resistant silicone or another sealant to fill any gaps between the frame and glass. This step is crucial for maintaining insulation and preventing moisture entry. Allow the sealant to cure fully before touching or painting the window frame.
Tools and Materials You May Need
- Measuring tape
- Utility knife or putty knife
- Glazing tape or silicone sealant
- Safety gloves and goggles
- Screwdriver or drill (if fixing secondary glazing)
- Glass suction lifter (for handling sealed units)
- Double-glazed glass units or secondary glazing panels
Maintenance Tips After Retrofitting
Regular Cleaning
Clean the glass and frame using non-abrasive cleaners. Avoid harsh chemicals that may damage the sealant or coatings on energy-efficient glass.
Check for Moisture or Condensation
If condensation appears between the panes, it may indicate a seal failure. While rare in properly installed systems, this requires prompt attention to prevent further issues.
Inspect Seals and Frames
Annually inspect the sealant and frame for cracks or damage. Reapply silicone or touch up paint as needed to maintain appearance and function.
Costs of Retrofit Double Glazing
The cost of retrofitting varies based on the type of glazing, size of windows, and labor involved. Here’s a general overview:
- Secondary glazing panels: £100£250 per window (DIY or supply-only)
- Sealed unit retrofit: £200£500 per window (including installation)
- Professional installation: Additional labor costs may apply, averaging £150£300 per window
While the upfront costs may seem high, energy savings and increased comfort often offset the expense over time.
Is DIY Retrofit Recommended?
If you are experienced with home improvement projects and have the right tools, DIY retrofitting can save money. However, precise measurements and installation are crucial. Poorly fitted units can lead to drafts, condensation, or reduced energy efficiency. For sealed unit retrofits, or for heritage properties, hiring a professional is recommended for best results.
Retrofit double glazing is a smart investment for homeowners seeking better insulation, noise reduction, and energy efficiency without the high cost of full window replacement. By carefully assessing your current windows, choosing the right system, and following the correct installation process, you can enjoy the benefits of modern glazing while preserving the charm of your home. Whether you opt for secondary glazing or sealed units, the upgrade will contribute to a more comfortable and energy-efficient living space for years to come.