Repair & Restoration

windows & doors

Rotten, draughty, hard to operate sliding windows? We can help.

If your charming old windows or doors look ready for the scrap yard, think again!
Rotten, draughty, unsightly windows or doors? Our restoration service is tailored for you.
Design Build Joinery explains the process of repair

If you love the period charm and heritage innate in your wooden sliding sash windows but hate the draughts, rattles, rot and heat loss that can also be part and parcel with an older property then you need help from the experts. With over many years’ experience repairing windows across the London, you can trust Design Build Joinery.

The replacement of sash windows is, in many cases, completely unnecessary. There are very few instances where damage and decay cannot be repaired using the right knowledge and tools. Repair work will depend on the damage. Decaying timber, broken sash cords, damaged pulleys and broken glass, will all need replacing.


Traditional timber sash windows are an essential feature of a period buildings character. Therefore it is vital to retain them, not only because of the aesthetic appeal, but because they add value to your property. Also known as a sliding sash or vertical sliders, they rely on a weighted system that allows the heavy sashes to lift and fall with ease. In order for the sashes to move in the box and operate smoothly, there is a 3mm gap between the sash and the frame which is often the cause of draughts, rattles, dust and rain ingress and heat loss. 


Our service focuses firstly on window repair and secondly on upgrading their performance.

What happens during the renovation process?
  1. Windows are carefully removed from the window frame.

  2. if necessary The glass is removed and then the old putty can be scraped away.

  3. Any decaying timber in the units, frame or sill is routed out to expose the “sound” timber.

  4. The joints are cleaned and any rotten wood is routed out.

  5. Occasionally, new timber is spliced in or replaced where the existing timber is beyond repair.

  6. Our unique epoxy resin, VR90, is used to fill the cavities and is moulded to match the existing profile of the timber.

  7. The sash and Frame are sanded or we burn the paint and always primed.

  8. The windows are then upgraded by fitting Brush Parting bead and draughts proof Sealing System

  9. The window is finished and painted by Dulux Weathershield Exterior paint.

  10. Sash cords or chain & pulleys are replaced, New Hardware Fitted and the sashes correctly balanced to ensure smooth operation of the windows.

  • We also work on casement windows and other timber windows and doors. Such diversification and decades of experience have made us the UK’s leading period window specialists.

Glazing Requirements

Many want to know if they can have new double-glazed units fitted into their existing timber sashes. The advice is to be careful — these windows were never designed to take two panes of glass, each thicker & heavier than the original.

The glazing bars in old sash windows are often not deep enough to take sealed double-glazed units, which ultimately leads to premature misting. we can do but we not recommended !!

Another option is to have new sashes made to fit your existing frames and to match the originals. DBJ use new slim glazing units and traditional methods of carpentry for an authentic look.

Costs of repairing sash windows

Prices will vary based on the extent of the damage also It depends on how much work each window needs:


  • For a recondition and new draught seals (this included stripping, priming and painting) = costs approximately £300-£500 per window inc Frame & Architrave.

  • Double-glazed sash replacements only, to fit into existing frames = approximately £500 per sash

This is just an estimate though, and we do offer a free no-obligation survey and quotation so we can come and see the windows and talk you through our service and the best options available to you. Our quotation gives you a full price breakdown, window by window.

Refurbishment Benefits
  • No more draughts

  • No more rattles

  • Reduced external noise levels

  • Improved insulation and thermal efficiency

  • Reduced dirt and dust

  • Correctly hung windows that operate smoothly

  • Extended window life

  • Improved security

  • Add value to your property

Our timber window repair services are excellent quality and value, but we will only recommend them to you if we believe they represent a good long-term investment. If your timber windows or doors are beyond repair we will always recommend partial or full replacement.



How much will it cost to renovate my windows?

It depends how much work each windows needs but standard draught proofing without replacing rotten sills, glazing etc starts at approximately £350 per window. For a more accurate quote please call us on 01992214834 to arrange a free no obligation survey.

How long will my window renovation take?

The time taken will vary depending on the survey result. Typically we work to a one window per day time scale although this can be adjusted if necessary to suit your requirements.

Is it possible to install double glazing into my original sash windows?

This depends entirely upon what type of window you have, however we have developed a service that will more than likely meet your requirements, namely by replacing your existing moving sashes with new, slim double glazed replicas into the original box frames. Find out more here

Will renovation reduce outside noise levels?

Noise is subjective but our Sealing System (draught proofing) have been independently tested and proven to significantly reduce sound intrusion also you can use acoustic glazing as well.

How does the our Sealing System improve comfort levels?

The main complaints we hear about are draughty, rattling windows. Our draught proofing system closes the gap around the sashes, eliminating draughts, rattles and reducing dust ingress and heat loss.

Do you only renovate sash windows?

We specialise in sash windows but we also renovate, draught proof and manufacture new casement windows, Yorkshire sliders, French doors and anything timber.

Do I need scaffolding?

Where possible we do all work in situ and take the sashes out from the inside of the property. Because of this we ask that the rooms we will be working in are cleared of any obstructing furnitre, we will cover any remaining furniture with dust sheets. If scaffolding is necessary we will always discuss this with you in advance of the order being placed.

Which is better: repair or replace?

Repair is cheaper in the short term, but may not provide the best long term solution. Our expert surveyors will be able to recommend whether your windows need replacing or repairing when carrying out a site survey, and will always recommend the best product for your requirements.

More information
Contact Us
Connect With Us

0800 130 3003

0203 969 33 81

Email us

Design Build Joinery Ltd,
415-417 Hendon Way

Hendon Central


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© Copyright 2020 Design Build Joinery Limited, Company No. 11212504 - Registered in England and Wales



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