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Case Study – French Doors & Windows

Aluminium is an excellent replacement for traditional steel french doors and windows.

The brief

Our customer had built a new garage extension and came to us because they wanted a specific look. They wanted slimline aluminium for a steel look but without the steel door price tag! They also wanted improved thermal values and less maintenance. The customer had employed an architect so we could use the architectural plans to work out the size of the apertures. We were supplied with the building plans for the property.

We visited the property before any work started, so that we could ensure what we were supplying would deliver the look and feel the customer was aiming for. It was important that we blended the look in with the rest of the property, as this was a single-storey extension and they can sometimes look out of place.

Our approach

We met on site with our clients to discuss their plans.

We advised the customers to choose black aluminium frames with bespoke nickel chrome Art Deco handles (also available in brass). The extension was built with two openings ready for our doors to be fitted and they look fantastic!

Product focus

The minimalist Alitherm Heritage range in aluminium was perfect for this project. The thermal values of aluminium are much better than steel and also require less maintenance as well as being around half the price. Our range of ultra-slim aluminium French doors give the same look of traditional steel French doors.

heritage aluminium french doors windows HD

The result

The result is an extension to the existing property that looks like it was always part of the house. The customer has achieved their desired look and has created the space they wanted. Everything blends together perfectly and the husband even has his own snooker room.





The Smart Alitherm installation is a standard residential casement-style system designed to replace old, draughty, poorly insulated windows. This is also great for new build projects where slim sightlines, minimal maintenance, and low U values, to comply with modern building regulations, are essential.


The amazing features of these products include:

  • Available in 20 colours at no extra cost— subject to quantity ordered
  • Polyester power-coated, making them virtually maintenance-free
  • Can be fitted into original timber sub-frames or directly to brick or stone
  • 200 RAL alternative colours available at a minimal surcharge
  • A range of bespoke ironmongery available
  • A range of external aluminium or hardwood cills


Our range of ultra-slim aluminium French doors are perfect for replicating the Art Deco style, while also lending themselves to a more contemporary style. Manufactured in the UK, using the highest quality materials, our aluminium French doors comprise of double polyamide thermal break sections which dramatically minimise any chance of condensation. Aluminium French doors and windows offer an excellent and cost-effective alternative for replacing draughty, old steel windows. We use slim sightlines and thermal break technology as well as the latest Low-E Planitherm double-glazed units, which are argon gas-filled, and include Swiss warm-edge spacers for added insulation.

Our Google Reviews

  • The Window Sanctuary replaced all my old Crittal Windows with slimline heritage aluminium windows to retain the period look of my grade 2 listed property and furthermore replaced the old rotten timber sash windows with new hardwood timber sash windows bringing the property back to life. The guys were hardworking very knowledgeable and very professional I wouldn’t hesitate to recommend this firm highly enough Warm regards Fraser Owen

    thumb Fraser Owen
    April 4, 2022
  • We had our conservatory doors replaced with by-fold doors by The Window Sanctuary and are very pleased with the results . The company were very helpful and spent lots of time with us answering our questions before we actually placed our order. They were very efficient with the installation process and we would recommend them. Competitive price too.

    thumb Royston Firman
    January 12, 2021
  • Great family company. Quality workmanship. Highly recommended.

    thumb Mark Childs
    July 4, 2021
  • We recently had a new front door and windows fitted. Very efficient service from start to finish with everyone extremely helpful. The fitter was very careful especially bearing in mind it was raining on the day of fitting. Would definitely recommend.

    thumb Chris Shortman
    February 23, 2021
  • I cannot recommend “The Window Sanctuary “ enough. We have a very modern property with large expanses of glass, Aluminium frames were advised and were very competitively priced. The level of customer service was exceptional throughout, the installation process caused minimal disruption and the finished windows and Bi-fold doors look fantastic

    thumb meena kharade
    October 31, 2019