How To Double Glaze A Timber Window?

Timber windows are popular due to their timeless elegance and attractiveness, but they aren’t as energy-efficient as newer double-glazed options. Adding a second pane of glass to an existing window creates an insulating barrier that aids in heat retention, noise reduction, and condensation prevention.

Homeowners who wish to enhance their home’s energy efficiency without altering its aesthetic value often choose this modification.

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The installation of double glazing may be the answer for homeowners whose homes have timber windows and are looking to improve their energy efficiency. In addition to improving comfort and decreasing energy costs, this technique also increases your home’s value.

Planning, being precise, and having some ability are all necessary when double-glazing timber windows. Starting with an evaluation of your current windows and ending with installation, this tutorial will show you how to replace single-glazed timber windows with double-glazed ones.

If you want to know how to double-glaze timber windows successfully, this tutorial is for you, whether you’re a seasoned DIYer or thinking about hiring a specialist.

How To Double Glaze A Timber Window?

Double glazing a timber window involves adding a pane of glass to create an insulated barrier. This can improve energy efficiency, reduce noise, and minimize condensation. Here’s a step-by-step guide to double-glazing a timber window, read more here:


Assess the Existing Window

  • Check the Condition of the Frame: Make sure the timber is in good condition with no signs of rot or severe wear. Repair or replace damaged wood.
  • Determine the Style of the Window: Understanding the type of window (casement, sash, etc.) helps in planning the double-glazing installation.


Choose Your Double Glazing Method

  • Secondary Glazing: Adds pane on the inside of the existing window, creating an air gap.
  • Replacement Double Glazing: This involves replacing the entire window unit with a new double-glazed unit.
  • Retrofitting Double Glazing: Requires replacing the single pane with a double-glazed unit while keeping the existing frame.


Measure and Plan

  • Measure the Window: Accurately measure the height, width, and depth of the frame. These measurements will determine the size of the double-glazed unit or secondary glazing.
  • Choose the Glass Type: Consider low-emissivity (Low-E) glass for better insulation, and choose a suitable gas for the insulating gap (like argon or krypton).


Prepare the Frame

  • Remove the Existing Pane: Carefully remove the glass from the window frame. This may require removing glazing putty or other fasteners.
  • Clean and Repair the Frame: Make sure the frame is smooth, clean, and free from debris or old glazing putty.


Install the Double-Glazed Unit

  • Insert the New Glazing: If retrofitting, carefully place the new double-glazed unit into the frame. Ensure it’s level and properly aligned.
  • Secure the Glazing: Use glazing putty or modern sealants to hold the glass in place. Apply glazing beads or trim to secure the glass.
  • Ensure a Tight Seal: Proper sealing is crucial for insulation and preventing drafts. Ensure there’s no gap between the frame and the glass.


Reinstall the Window

  • Reassemble the Window: Put the window back in its frame, ensuring it operates smoothly.
  • Check for Gaps: Test the seal and adjust if needed to ensure no air or water can enter.


Test and Finish

  • Test the Window’s Functionality: Ensure it opens and closes smoothly, and there’s no draft.
  • Apply Finish to the Frame: Paint or varnish the timber to protect it from moisture and wear.
  • Final Check: Inspect the entire installation for stability, and ensure proper insulation.


Double glazing a timber window can be a complex process. If you’re not experienced with DIY projects, consider hiring a professional to ensure the job is done correctly. This way, you can enjoy improved energy efficiency and noise reduction without compromising on the aesthetics of your timber windows.

Can You Put Double Glazing On Yourself?

Yes, you can install double glazing yourself, but it can be a complex task requiring specific tools, skills, and precision. Here are some considerations to determine if it’s a suitable DIY project for you:

Considerations Before DIY Double Glazing

  • Experience Level: If you’re experienced with home improvement projects, particularly those involving windows, you’ll find it easier to undertake double glazing. If you’re new to DIY, this task might be challenging.
  • Tools and Equipment: Double glazing installation requires various tools, such as measuring tapes, glazing knives, drills, sealants, and possibly glazing beads or putty. Ensure you have all the necessary tools.
  • Window Type: Some window styles, like casement or sash, can be more complex to retrofit. Assess the complexity of your existing windows.
  • Quality and Accuracy: Double glazing must be installed with precision to ensure proper insulation and avoid drafts. Any misalignment or improper sealing could affect energy efficiency.
  • Safety: Removing and installing glass panes involves risks. Safety gear, like gloves and protective eyewear, is essential. If you’re uncomfortable with these risks, consider professional installation.
  • Building Regulations: Ensure your double-glazing project complies with local building codes and regulations. In some areas, certain types of work require permits or professional certification.

DIY Double Glazing: Step-By-Step

If you’re confident in your abilities and have the right tools, here’s a general outline of how you could double-glaze a window:


  • Measure the Window: Accurate measurements are crucial. Measure the height, width, and depth of the frame to determine the size of the double-glazed unit.


  • Choose the Glazing Method: Decide whether to retrofit with a new double-glazed unit or add secondary glazing to the existing window.


  • Purchase Materials: Buy the double-glazed unit or secondary glazing system according to your measurements. Ensure the glass type and insulating gas meet your needs.


  • Remove the Old Pane: Carefully remove the existing glass, taking care not to damage the frame. This may require removing glazing beads or putty.


  • Prepare the Frame: Clean the frame, removing any old putty or sealant. Sand and repair any damage to ensure a smooth, even surface.


  • Install the New Glazing:
    1. For retrofitting: Insert the double-glazed unit into the frame. Secure with new glazing beads or putty/sealant.
    2. For secondary glazing: Install the additional pane on the interior side of the window according to the system’s instructions.


  • Ensure a Tight Seal: Proper sealing is crucial to avoid drafts and ensure insulation. Use sealants or putty to create a tight, weather-resistant seal.


  • Test and Finish: Ensure the window operates smoothly without drafts or leaks. Apply a protective finish to the timber frame to protect it from moisture.


While double glazing can be done as a DIY project, it requires careful planning, precision, and some level of experience with home improvement. If you’re unsure about any step, or if the project seems too complex, it’s best to consult or hire a professional.

This will ensure the job is done correctly, safely, and in compliance with local regulations, providing you with a long-lasting and energy-efficient solution.


By installing double glazing on your home’s existing timber windows, you can greatly improve its energy efficiency, comfort, and noise insulation. You can do this job on your own if you’re handy with tools, but it will need a lot of preparation, precise measurements, and skill.

To install secondary glazing or a double-glazed unit, you must first prepare the window frame. Then, you must ensure a tight seal to avoid heat loss and drafts.

Do your research on the unique needs of your window type, gather the necessary tools, and take all necessary safety measures before attempting to double-glaze your windows on your own. But if you don’t know what you’re doing or have any doubts about the process, it’s best to get a pro.

Calling in the pros will guarantee your windows are installed correctly, according to local construction requirements, and have a high-quality finish that improves their usefulness and value.

In the end, double glazing your timber windows is a wise investment, regardless of whether you choose to install it yourself or hire a professional.

It has the potential to improve the quality of life, raise the value of the home, and decrease energy costs. Before deciding on a course of action, carefully consider your requirements and strengths and weaknesses.

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