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Should You Replace or Repair Your Double Glazed Windows?

Measuring replacement double glazingReplacement double glazing is an investment that will improve the energy efficiency of your home and potentially add value. However, double glazing is expensive, and as a homeowner or renter, you should thoroughly understand your options before paying for new glazing.

  • New double glazing is typically more energy efficient, so it can save you on your energy bills.
  • Upgrading from B rated glazing to A rated glazing can save you £55-110 every year.
  • Expect to pay a minimum of £300 per window for UPVC frames
  • Double glazing typically lasts 10-20 years. Wood frames can last 40 or more.


If you’re considering replacing your double glazing, keep reading to learn about your options and how to get the best deal.

You will find in this guide:

How much does replacement glazing cost?

Whats included in a quote

How long should double glazing last?

Benefits of replacing windows

When to replace double glazing?

When to repair double glazing?


How much does it cost to replace windows?


Double glazing costs vary depending on several factors including your location, your windows, the size of the windows, the frames, and what you need replaced. You will likely pay between £300 and £1,500 for new glazing and frames, but specific costs depend on the windows you choose.

In most cases, materials, size, type, and installer are the most important factors that affect costs. For example, large bay windows can cost thousands window while a small casement window may cost just over 2 figures.


What’s included in a double glazing quote


In most cases an online quote will include a preliminary estimate based on details you give to the installation company. However, it is important to note that no online quote is 100% accurate because the installer must take additional costs such as the height and location of the windows into account. This means that online quotes are guidelines, which you can use as a guideline until the installer completes the inspection.

A quote should include:

  • Removing old windows
  • New glazing
  • New frames
  • Installation
  • Clean-up

Once you have a contract, your installer cannot legally go over the rate listed on the contract.


How long should double glazing last?


Double glazing is almost always limited by the frames and the seals. This means that the average lifespan of glazing will be 10-35 years, which will vary depending on the installation, quality of materials, and the location of the windows.

Your frames will also affect the lifespan of the windows.

You can expect the following costs for budget to mid-range 60 x 90 cm casement window. A higher end window will cost significantly more in every category.

Material   Cost   Lifespan Care
UPVC £250-570 5-24 Years Low-maintenance



40+ Years Low-maintenance



5-24 Years High-maintenance

£845 – £910


16-39 Years High-maintenance

In most cases, you reach the maximum lifespan of windows by regularly caring for them, keeping them clean and dry, and closing windows properly. If glazing develops problems but your frames are still in good shape, you can easily replace the glazing in your frames to save money.

Sealing – In most cases, seals are the first part of a window to develop problems, especially if the frames are well-cared for. Sealing should last 10-35 years and should be covered by a manufacturer’s warranty for a minimum of 5 years. Good windows should have a warranty of 10 years or longer.

Paint – Wood and composite windows will require paint or finishing every 2-5 years to protect the wood and prevent them from rotting. If this isn’t done, the windows could fail significantly sooner and this will void the warranty.

Check Your Warranty

If your glazing starts to fail and your windows are still under warranty, you could have them replaced or repaired free of charge. However, if the damage is due to improper care or use, your warranty will be void. Most quality windows feature the following warranties:

Warranty    Length  
Hardware   10 Years
Workmanship   5-10 Years
Sealing   10 Years
Stain and Paint Finishes   5-8 Years


Top Benefits


Replacing old double glazing can help you to save money, but you can get other benefits as well.

Save money – Modern double glazing can save you significantly on your energy bills. While replacing double glazing won’t save you enough to pay for the glazing in most cases, it can save you £55-150 per year. Why? If your glazing is 10 years or older, it is likely B rated at best. Upgrading to low E glass with a good U rating will reduce your energy bills considerably. Old double glazing typically has a U rating between 5 and 3, and modern double glazing typically has a rating of about 1.6, meaning you can halve the energy that escapes from your home through the windows.

Noise reduction – Replacing double glazing allows you to choose a model with better noise insulation to reduce outside sounds. This may be worth the upgrade on its own if you live in a noisy home, even if you’re planning to move, because reduced noise will increase the value of your home. Acoustic double glazing can reduce noise levels 75-95%.

Style changes – Whether you installed the glazing yourself and just don’t like the style anymore or moved into a home and don’t like the windows, installing new glazing allows you to choose the style and model of windows in your home.

Material changes – UPVC is the most commonly installed window frame in the UK, but it’s also the least valuable. If you want to add value to your home, choose a longer-lasting material, or choose another material for aesthetic reasons.

Upgrading to triple glazing – Upgrading to triple glazing from double glazing can add to the insulation and the soundproofing of your home. While modern double glazing has a U value of about 1.5, triple glazing has an average U rating of 0.8, just over the U value of a standard wall, which is 0.5. While triple glazing will not likely pay itself off, it can help you to reduce noise in your home, cut energy bills, and reduce problems like hot and cold spots caused by heat escaping.


When you should replace your windows


There are numerous reasons to replace old glazing. However, if your glazing only needs repair, you might be able to save money.

Damaged Glass –If your glass is damaged, you have to replace it. However, you can save money by keeping your old frames if they are in good condition. Most frames are designed to have the glass replaced, which makes it easy to simply update your broken or damaged glass.

Damaged Frames – In most cases, if your frames are damaged, you will need new glazing as well. Why? It’s difficult to remove glazing from a window in one piece, unless the sealing is completely damaged. This includes rotting wooden frames, warping UPVC, discoloured frames, and broken frames and sashes.

Broken Sashes – If your sashes are broken, you can likely simply replace the sashes without replacing the glazing.

Fogging or Condensation – Fogging and condensation between the panes mean that the sealing on your double glazing is broken. You cannot fix this and will have to have your glazing replaced.

Old Seals – Most sealing will only last for 10-20 years. In some cases, your sealing might last only 5 years. In this case, you will likely have to replace your double glazing or have it resealed, but you can keep your frames.


Should double glazing condensate?


Double glazing can condensate for several reasons, and they aren’t always bad.

Exterior Condensation – Condensation on the outside of the glass can be annoying, but it is not a problem. Most modern double glazing is very energy efficient, which means that it prevents air from moving through the glass. Because the interior of the house is likely much warmer or cooler than the outside, this can cause water to bead up on the outside, just like when you put ice in a glass of water. If this is a problem, try opening a window for a few minutes each day to increase airflow.

Interior Condensation – Interior condensation is caused by the same issue as exterior condensation. However, it usually means that your home is too damp, or that your windows are fogging up while you are cooking or bathing. Consider opening a window during these times and remember to towel window sills dry if too much water beads up.

Condensation Between the Glass – If your double glazing is fogging up or shows water beading between the panes, the sealing on your glazing is old or damaged. This likely means that you have to reseal or that you should replace the glazing. If condensation is building up between panes, air is moving between the panes and taking hot and cold air with it, which reduces the energy efficiency of your home.

Can I fix condensation myself? – It is a common myth that you can fix condensation between double glazing by drilling a hole to allow air to circulate, this technique will only work for a few weeks to a few months. You will have to keep repeating the ‘fix’ to keep condensation away, and each ‘fix’ will lower your energy efficiency.


Replacing single glazing


If your home currently features single glazing, you can possibly save money by upgrading to double glazing. For example, if you have old C rated glass, you could save as much as £175 per year with double glazing. Depending on the frames you pick, you could pay your investment off in as little as 10 years.

Secondary glazing – If you have old single glazing but the frames and the glass are in good shape, you may be able to save money by installing secondary glazing. Here, the installer will place a second pane of glass against your frame and seal it. While not as efficient as double glazing because it does not include a layer of gas to buffer against hot and cold weather, it will greatly improve the energy efficiency of your home at a very reasonable cost.


When you can repair your windows


In many cases, you can choose to repair your double glazing rather than having it replaced. This may be a good choice, especially if your windows are less than 10 years old. However, if your sealing, glazing, or frames are nearing the end of their lifespan, you are more likely better off replacing them.

Resealing double glazing – In some cases, a competent glazier or fitter may be able to reseal your windows. This means removing the old putty and adding a new desiccant and putty to reseal the windows. If you have Argon double glazing or a similar gas-filled window, this method will not work.

Overhauling and draught reduction – An overhaul and draft reduction will typically include resealing, new sashes, and other repairs as necessary to draught proof and seal the windows. This is the best option if your windows are in mostly good condition but you are getting drafts or condensation.

Retrofitting old frames – Retrofitting old frames is the cheapest way to replace double glazing because you don’t have to purchase new frames, which can save you 50% or more on the cost of buying windows. However, it may not be possible if you have old frames, the frames aren’t deep enough for your replacement glass, or your frames are damaged.

What are double glazing inserts? – Double glazing inserts install around the frame of a window to add additional sealing to the window. However, these types of fixes are only temporary at best and will not seal your window for long.

Is repair the best option? – If your window is old, damaged, or nearing the end of its lifespan, you may have to replace the windows in a few years anyway. This can mean that repairing the windows will cost more in the long-term than simply replacing the windows now.


Can I replace double glazing myself?


Unless you are a professional window fitter or glazier, the answer is usually no. Glazing is difficult to seal and easy to break, and mistakes will cost you hundreds of pounds.


Can I buy double glazing myself?


You can typically save 20-30% over the cost of buying double glazing through an installer by going direct to manufacturer for your glazing. However, this can backfire if the installer offers deals for purchasing fitting and windows together, which many do. It’s important to get quotes to check costs and what is included before purchasing glazing yourself.


How long does it take to replace double glazing?


Replacing double glazing will typically take 2-3 weeks’ total, and about 8-12 hours for actual window fitting.

  • Survey to provide firm quote: 1-2 hours.
  • Measuring windows and openings: 1-3 hours.
  • Removing Existing Windows – 30 minutes-2 hours per window
  • Fitting and sealing the windows: About 1-2 hours per window.
  • Finishing and adding trim: 30-45 minutes per window
  • Cleaning up debris and tools: 2-3 hours.
  • Total: 12 – 26 hours for a 4-window installation

Multi-story homes will take longer to fit.


Will replacement double glazing save me money?


Double glazing will likely reduce your energy bills but unless your current windows are very old or you get a very good deal on replacement glazing, they will not likely pay themselves off. However, you can increase the value of your home, increase comfort, and reduce the noise level in the home, which can be beneficial as well.

If you are concerned with your windows paying themselves off, make sure that you know the current energy rating for your windows, and then look for UPVC windows in low E glass to maximise your energy savings.


How to save money


If you are replacing double glazing it is important that you get the best price possible to reduce your investment. While double glazing is expensive, you can greatly reduce costs using a few simple tips.

Know what you need – Double glazing sales representatives are often tasked with charging you as much as they think you can pay for, which means that you might get a ridiculously high quote. It’s not uncommon to see quotes drop by as much as £10,000 over the course of a single setting, and even then, it’s likely high. Make sure you know what you need, what it should cost, and why you need it so that a sales rep cannot talk you into a more expensive option. To make sure that you have time to research, don’t accept any offer same-day, even if they’re trying to offer you a ‘today only’ deal.

Using old frames – Retrofitting your old frames can save you a great deal, even if you want to replace your old glass with higher quality glazing. Just make sure that the frames are in good shape and that they are deep enough for double glazing.


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