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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

  • A great experience with The Window Sanctuary. They supplied and installed some celestial windows and roof lights to a loft conversion that we carried out. It is a period property with original sash windows and it was important to us that the new windows were in keeping with the character of the original house. We are delighted with the finished product. The customer service was very good and they were amenable when our architect got carried away and the window sizes increased quite materially from the original quotation - thereby working hard to minimise the extra costs. The quotation process was quick and efficient. Their surveyor, Steve, was very professional and also had a strong technical knowledge to help advise us during the build stage. The installation team were very professional and worked extremely hard to get the windows fitted during poor weather. The lady on the front desk, Jeannette, was also very friendly/helpful despite my numerous calls to the office throughout the process. There were a few delays but this was the result of CoVid as opposed to anything in their control, and Simon worked hard to get the order pushed through the suppliers and installed promptly. I always like to support local businesses and this one did not disappoint. Will definitely use them again going forward for any further works. Thank you.

    Richard Simpson Avatar Richard Simpson
    February 12, 2021
  • The Window Sanctuary supplied and installed our patio doors. We are extremely happy with the service they provided and couldn’t be happier with how the doors have turned out. They are exactly the look and quality that we were after.

    ben jeffree Avatar ben jeffree
    May 21, 2021
  • 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

    Fraser Owen Avatar Fraser Owen
    April 4, 2022
  • Fantastic service and quality products I had my front door replaced by The Window Sanctuary and I am delighted with the results. The fitters were punctual and polite. The process was so quick & easy and any queries I had were dealt with very efficiently. I have no hesitation in recommending this company and will definitely use them again in the future.

    James Collins Avatar James Collins
    January 8, 2020
  • 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.

    Royston Firman Avatar Royston Firman
    January 12, 2021