Double Glazing Condensation Repair Cost

Got misted or blown double glazing? Condensation between the panes usually means the window seal has failed, a common issue that reduces energy efficiency and visibility.

The average cost to replace a single blown unit is between £55 and £145, depending on the size of the window. Replacing all units in a three-bed semi-detached home typically costs between £1,400 and £2,500.

You can use MyJobQuote to find window specialists near you and get free, no-obligation quotes.

Prefer to learn more first? This guide explains what causes condensation inside double glazing, when you can repair it, and how much replacement typically costs.

Where Is the Condensation?

Before looking at costs, it helps to identify where the condensation is forming — this determines whether you have a glazing fault or a ventilation issue.

Condensation on the Outside of the Glass

Moisture on the outer pane, typically in the morning, is normal and not a cause for concern. It indicates the outer glass is cooler than the surrounding air — a sign your double glazing is doing its job by retaining heat inside the property.

Condensation on the Inside of the Glass

If condensation is forming on the room-facing surface of the glass, this is a ventilation issue rather than a glazing fault. Everyday activities like cooking, showering, and drying clothes indoors raise humidity levels. Try opening trickle vents, running extractor fans, or using a dehumidifier before calling a specialist.

Condensation Between the Panes

This is the type that requires professional attention. When the window seal fails, moist air enters the gap between the panes and the insulating gas escapes — causing the unit to mist up from the inside. This is known as a blown window, and the failed sealed unit will need to be repaired or replaced.

The rest of this guide covers costs and options for condensation between the panes specifically.

How Much Does It Cost to Remove Condensation From Windows?

When the seals on double glazed units fail, moisture can enter between the panes, creating misted or foggy windows. In the past, the only fix was to replace the entire unit, but today some specialists can repair and reseal blown windows without removing the frame. This modern method can be up to 50% cheaper than full replacement.

Resealing or replacing double glazing isn't a DIY job — the units are made to precise measurements and resealing requires specialist equipment.

Well-maintained double glazing can also improve a property's energy efficiency rating and kerb appeal, which is worth considering if you are planning to sell.

If your windows have condensation inside the glass, it's best to contact a local double glazing repair company. One way to get quotes from local window specialists is to use the free "Post a Job" service on this website.

Can Condensation in Double Glazing Be Fixed?

In most cases, yes. If the condensation is sitting between the panes, it means the sealed unit has failed — but this does not mean you need to replace the entire window.

There are 2 main solutions, depending on the condition of your windows:

Unit replacement: The most common fix. A specialist removes the misted glass unit from your existing frame and installs a brand-new sealed unit custom-made to fit. The frame stays in place. This is the standard approach for most blown windows.

Specialist resealing: Some companies can repair a blown unit without replacing the glass, by drilling a small hole, removing the moisture, and resealing the unit. This can cost less than a full replacement, though it is generally considered a shorter-term solution.

Repair is not always possible. Toughened glass (common in doors and some bathroom windows) cannot be resealed, as drilling into it causes the glass to shatter. In these cases, unit replacement is the only option.

If the window frame itself is damaged, warped, or rotted, neither repair option will solve the underlying problem and a full window replacement is required instead.

Find Tradespeople, compare up to 3 quotes!

It's FREE and there are no obligations

Get started

Double Glazing: Repair vs Replacement

Deciding whether to repair or replace a window often comes down to the condition of the frame and the specific problem you're facing. A professional repair can solve many common issues for a fraction of the cost of a full replacement.

Blown & Misted Double Glazing Repair Costs

For a blown or misted window, a repair is almost always the most sensible and cost-effective option, as long as the window frame itself is in good condition.

The replacement of a single unit is a relatively simple process, which for a standard unit can be completed within the hour. Replacing all windows in a property is typically considered a full day's work.

A professional repair means replacing the entire sealed glass unit — known as an insulated glass unit (IGU) — with a brand-new one. The new unit is measured and custom-ordered to fit your existing frame. For a full breakdown of replacement unit costs by window size, see our window glass replacement cost guide.

Choose repair if:

• The window frame (uPVC, wood, or aluminium) is structurally sound, free of cracks, warping, or rot.
• The only problem is the misting or cloudiness between the panes.
• You are happy with the style and operation of the window.

Specialist Resealing Costs

An alternative to unit replacement is specialist resealing, where a technician drills a small hole in the glass, extracts the trapped moisture, inserts a drying agent, and reseals the unit. This can cost between £50 and £100 per window and is sometimes marketed as a cheaper short-term fix.

However, most window specialists recommend full unit replacement over resealing, as resealing addresses the visible symptom rather than replacing the failed component. A new sealed unit will typically come with a warranty of 5 to 10 years, whereas a resealed unit may not.

Note that resealing is not possible on toughened glass, Velux windows, or certain timber-framed units.

This process is sometimes referred to as "regassing" double glazing, as it involves replacing the insulating gas — typically argon — that sits between the panes. The terms are used interchangeably by different specialists, though the process and cost are broadly the same.

Full Window Replacement Costs

A full replacement involves removing the entire window frame and installing a brand-new unit. This is a more significant and expensive job, but it is the correct solution in certain situations.

The table below provides estimates for a complete replacement, but for a full picture see our new windows cost guide.

Typically you'd choose a full replacement if your windows have issues beyond condensation or misting.

• Damaged Frames: If the frame itself is warped, cracked, or (in the case of timber) rotted, a simple repair won't solve the underlying problem.
• Major Physical Damage: Severe damage to the entire window from an impact or break-in often makes replacement the only viable option.
• Poor Energy Efficiency: If you are upgrading from old single-glazed or very old, inefficient double-glazed windows, a new, modern unit will provide significantly better thermal performance.
• Multiple Failures: If the window has a failed glass unit, broken hinges, or a faulty lock, the combined cost of multiple repairs may start to approach the cost of a new window, making replacement a better long-term investment.

Additional Condensation Removal Costs

Depending on the condition of your windows and the surrounding area, there may be additional costs to factor in alongside the repair itself.

Mould Removal

Where condensation has been present for some time, there is a risk of mould forming around the window frame or along the adjoining wall. Keeping the area well-ventilated can help limit this.

Small areas of mould can be treated with a shop-bought spray. For more extensive cases, professional mould removal services are available, typically costing between £400 and £500 depending on severity.

Window Repairs

If the frame itself is damaged rather than just the glass unit, a more extensive window repair may be needed. uPVC frame replacement typically costs between £250 and £750 per window.

Triple Glazed Windows

If you are already replacing units, it may be worth considering triple glazed windows as an upgrade.

On average, the cost of installing triple glazing is around £4,400, although this will vary depending on the size of the property and the number of windows involved.

The energy saving over double glazing may be minimal in a well-insulated home, but triple glazing can offer additional benefits such as improved sound insulation — particularly useful for properties near busy roads or in exposed locations.

Window Cleaners

Once repairs are complete, regular maintenance will help extend the life of your windows. A professional window clean typically costs from £40 per session.

Window cleaner costs vary across the UK, with prices in London and the South East typically higher due to the cost of living. The number of windows and the accessibility of your property may also affect the price.

Factors That Impact Double Glazing Repair Costs

Several factors will influence the final cost of your repair beyond the figures above:

• Number of windows affected
• Extent of the repair work needed
• Type of glazing
• Location and accessibility
• Window style — bay windows typically cost more due to the larger glass area involved

The more windows that need attention, the higher the total cost — though having multiple units replaced in a single visit will typically work out cheaper per window than separate call-outs.

What Causes Double Glazing Seals to Fail?

The seal around a double glazed unit is designed to last for many years, but several factors can cause it to break down prematurely.

• Poor original installation: If the unit was not fitted correctly from the outset, the seal is more likely to fail early.
• General wear and tear: Over time, the sealant naturally degrades, particularly on south-facing windows exposed to prolonged heat and UV light.
• Frame deterioration: A warping or shrinking frame — common in older timber windows — can put stress on the sealed unit and eventually break the seal.
• Accidental damage: A crack or impact to the glass or frame can compromise the seal immediately.
• Harsh cleaning products: Abrasive or solvent-based cleaners can degrade the sealant around the unit over time.
• Temperature fluctuations: Repeated expansion and contraction of the frame material through seasonal temperature changes gradually weakens the seal.

Ask a Trade

Got a question that only a tradesperson can answer? We have thousands of trades ready to answer any question you may have.

Ask your question

Doing it Yourself

Resealing double-glazed windows is not a feasible DIY project, as it requires previous experience and the use of specialist equipment.

While it is possible to take measurements yourself, the savings on labour costs would be minimal — and because measurements must be precise, even a small error can result in a replacement unit that does not fit the existing frame.

If this happens, no refund will be available — the unit will need to be remeasured and reordered at additional cost.

Most homeowners hire a local window fitter to carry out the work, both to avoid measurement errors and to ensure the installation is covered by a warranty.

Are Your Windows Still Under Warranty?

Before arranging any repairs, it is worth checking whether your double glazing is still covered by the original installation warranty. Many window installers offer warranties of between 5 and 15 years, and a failed seal may be covered at no cost to you.

To check, look for the paperwork provided at the time of installation. This should include the installer's details, the warranty length, and what it covers. If you no longer have the documents, contact the installer directly with the approximate installation date.

If the original installer has ceased trading, some warranty protection may still apply if the warranty was backed by a third-party insurance provider. Check the original documents for details.

Where no warranty applies, the costs outlined in this guide represent what you can expect to pay for repair or replacement.

Checklist: How to Find and Hire a Window Specialist

Before agreeing to any repair or replacement work, make sure your quote includes a total price, a breakdown of the work to be carried out, the materials to be used, and an estimated timeline. Here are the key things to check before hiring.

• Warranty on parts and installation: Confirm that the replacement sealed unit and the installation work are both covered by a written warranty. A reputable specialist should offer at least 5 years on a new unit.
• Check your existing warranty first: Before booking any work, check the paperwork from your original window installation. Many installers offer warranties of up to 15 years, which may cover the cost of replacement at no charge.
• Experience with your window type: Ask whether the specialist has experience with your specific window style and glazing type. Not all contractors work with toughened glass, timber frames, or Velux units.
• Measurements taken on-site: Confirm the specialist will take all measurements themselves before ordering a replacement unit. Incorrect measurements result in units that do not fit, and suppliers will not issue a refund.
• Insurance: The contractor should hold public liability insurance as a minimum. Ask to see evidence of this before work begins.
• Waste disposal: Check whether removal of the old unit is included in the quote. Some contractors charge separately for this.
• VAT and contact details: Ensure the quote includes the contractor's company name, address, contact details, and VAT number where applicable. Verify the VAT number is genuine.
• References and reviews: Ask for at least 2 references from previous window repair jobs and check independent online reviews before committing.