How much does double glazing repair cost?

Condensation between the two panes means the seal around the sealed unit has failed. Gas escapes, moist air gets in, and the window loses much of its insulation. It cannot be wiped away and it rarely clears on its own.

The fix is usually to replace just the sealed glass unit, not the whole window. The frame stays, the fitter measures the unit, orders a new one made to size, and returns to swap it in, usually in under an hour per window.

Expect £100–£250 for a small to medium unit, and £200–£450 for large units or patio door panels. Toughened or laminated safety glass, obscure bathroom glass and decorative leaded units cost more.

Some companies offer to drill and "de-mist" units instead. It can clear the view for a while, but it does not restore the seal or the insulation, so a replacement unit is normally better value.

Handles are the cheapest fix. A uPVC window handle costs £10–£30 to buy and most fitters charge £40–£90 supplied and fitted, less per handle if several are done on one visit. Take a photo of the old handle and note the spindle length so the right one is brought.

Hinges, properly called friction stays, wear out after 15–20 years. Signs are a window that drops, catches on the frame, or will not stay open. Replacing both stays on one window usually costs £60–£120.

On doors, a lock cylinder (the part the key goes in) costs £60–£120 to replace, and is worth upgrading to an anti-snap cylinder. If the handle is floppy or the door will not lock even when lined up, the multipoint mechanism inside the door may have failed. Replacing it costs £150–£300 depending on the make.

uPVC and composite doors settle over time. When a door drops it catches on the frame, the handle gets stiff to lift, and eventually the lock will not engage. Left alone this strains the locking gearbox, which turns a cheap adjustment into a costly repair.

Most dropped doors can be fixed by adjusting the hinges, which takes a fitter 30–60 minutes. Expect £50–£100.

Worn or flattened rubber seals cause draughts and rattles. New seals cost £20–£50 per window or door and are often done on the same visit as other repairs.

Repair if the frame is sound. Misted glass, broken handles, worn hinges and tired seals are all routine fixes that cost a fraction of a new window.

Replace if the frame itself is rotten, warped, cracked or badly discoloured, if several units have failed at once on very old windows, or if you want a real jump in insulation and security. A new uPVC window typically costs £400–£1,000 fitted, depending on size and style.

In England, replacing a whole window or external door must meet Building Regulations. The simplest way is to use an installer registered with a competent person scheme such as FENSA or Certass, who certifies the work for you. Replacing just the glass unit, a handle or hinges does not need this.

Size and glass type. Bigger units cost more, and safety, obscure, acoustic or decorative glass adds to the price.

Number of jobs on one visit. Most fitters have a minimum call-out of £50–£80, so getting several windows looked at together brings the price per repair down.

Access. Upstairs windows that can only be reached from outside may need a tower or ladders.

Parts. Common handles and hinges are cheap and carried in the van. Older or unusual makes of lock may need ordering.

1. Count the misted units and roughly measure each one. Budget £100–£250 each. 2. Add £40–£90 for each broken handle and £60–£120 for each window with worn hinges. 3. Add £50–£100 if a uPVC door needs adjusting, or £150–£300 if its lock mechanism has failed. 4. If it is a single small job, allow for a £50–£80 minimum charge.

Example: two misted bedroom units and a dropped back door. Units £200–£500, door £50–£100, so roughly £250–£600.

On BidMyJob you can post the job free with a photo of each window, and local window fitters and handymen send you their price.