Box Sash Windows

We supply and fit replacement wooden box sash windows


Box Sash Windows

Sash Window Supply & Installation


Supreme Carpentry offer a complete replacement box sash window supply and installation service for period properties in Enfield, Barnet, Haringey, Islington and surrounding areas in North London.


We typically find replacement sash windows are needed when the existing sash windows are no longer functional after years of wear and tear or rotting frames which cause difficulty in opening and shutting them.


Increasingly we find customers feel the need to replace them as part of improving the energy-efficiency of their home. The benefits of modern replacement sash window installations include improved insulation with modern double glazed units, leading to energy efficiency, enhanced aesthetics, ease of operation, and an increase in property value.


Our skilled team are here to help ensure the appropriate windows are chosen for you particular property and provide a complete installation to secure the long-term performance of your new windows. 


Our Replacement Box Sash Windows

Supreme Carpentry's replacement box sash windows are made to measure and both designed and manufactured to retain the timeless character features and elegance of the original sash windows found in your home. We are able to reproduce sash windows in the original style of period homes from the Georgian, Victorian, and Edwardian periods.


Thanks to modern window technology we are also able to provide all the benefits of modern glazing. We can fit slimline double glazed window units into your replacement sash windows to provide vastly improved insulation, minimising heat loss and reducing noise pollution from outside. Our replacement sash windows also offer improved draft and weather proofing your windows.


Our wooden box sash windows are produced in a joinery workshop in the UK and are guaranteed for up to 5 years. 

Replacing Your Box Sash Windows

Our box sash window replacement process typically involves the following steps:


Assessment & Site Survey


 One of our skilled window installers will visit your property to do a complete site survey. During the visit they will assess the existing sash windows to determine if they need replacement or can be repaired, and if there are any additional works required as part of the installation. They will also take precise measurements so the replacement box sash windows can be made especially for your property.


Window Selection & Specification


We will then be able to talk you through the window installation process and the window options. We usually advise our customers to choose replacement sash windows that match the architectural style of the building as well as improving the insulation and energy efficiency of their home. There are various options available including the type of wood, finishing details in the wood, fittings such as locks, lifters and safety stops, as well as a choice of single or double glazed window units.


Quotation & Approval:


Once we have completed the site visit, we will then put together a formal quotation specifying the windows to be provided, fittings and accessories, and the extent of the installation works. This is typically emailed to you within a few days of our visit.


Once you have reviewed and approved the quotation, we can then organise the manufacture of your replacement windows and schedule a date for the installation to begin. Windows typically take 3-4 weeks to be made in the joinery workshop.


Sash Window Installations:


On the day of the replacement window installation, the old sash windows are carefully removed, and disposed of properly. The window openings are cleaned, repaired, and prepped before the replacement window installation can begin.


Your new replacement sash windows are then fitted into the existing openings. The window installation process may involve attaching new frames, sashes, and hardware, as well as insulation which is crucial to ensure energy efficiency.


Once the sash windows are securely installed, any gaps are filled, and the surrounding trim is replaced or restored to give the windows a finished look.


A final inspection is then completed to make sure your sash windows are installed correctly and that they open and shut properly.


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