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Extension and Conversion

Turning a conventional garage into a minimalist extension


High drama in an extension with mezzanine

Many new homes come with integral (adjoining) or independent garages that often become dumping grounds for bikes, storage, etc. These spaces can provide valuable additional square footage for a lower cost as the structure is in place. As with all building work it is vitally important that all of the building work conforms to current building regulations and is inspected at key stages.

On this project we had a number of building and engineering challenges to turn a conventional garage into a minimalist extension with a curtain wall, bi-folding doors and dramatic mezzanine office. Substantial additional foundations and steelwork beams were required. We matched brick and mortar to the existing. And as with any modern building, full attention was paid to insulation, heating and energy efficiency. 

The minimalistic design of the building required complete precision of finish to attain the crisp look that the clients were looking for.

Nowhere is the sleek modern look more evident than from the office mezzanine on the first floor, above the original double garage with its stunning views enabled by the aluminium gable frame, set off by stainless steel and glass balustrades.

Coordination among client, architect and engineers ensured we understood and delivered both the practicalities of the build and the client’s design vision.

Project at a glance

See more extension projects from Smart Build or return to the list of all projects

The full Story

Case Study: Converting a double garage into a modern open extension

Our brief in this project was to semi convert the double, independent garage and adjoin the structure to the house in the form of two extensions. We were to create a first floor office mezzanine which involved stripping off the original roof and timbers and altering and extending the original pitch of the roof. The clients wanted a modern open feel to the extension area. To create an abundance of light, double sets of bi-folding doors were fitted, with glazed curtain walling, creating panoramic views.

The build was challenging for several reasons:

  • The access was very tight which made getting machinery and muck away difficult.
  • The ground levels close to the extension fell away dramatically. This therefore dictated that the foundations had to be piled to give the building the necessary stability.
  • There was a substantial amount of steelwork required to carry the vaulted ceiling and curtain walling.
  • The minimalistic design of the building required complete precision of finish to attain the crisp look that the clients were looking for.


Our structural engineers calculated the pile design and our piling contractors bored seven-metre piles that were caged and poured with concrete. The piles were then cropped, the oversite was excavated and a caged ring beam was fitted to the piles. This was then shuttered and concreted. Piling is generally the worst case scenario as this form of foundation work is very costly. However if you are building on made up ground or around trees etc then this is often the best solution.


A brick match and a mortar colour match was then established and the superstructure was built. We had to strip off the original double garage roof and supply, profile and fit two steelwork ridge beams and steel crank beams to support the roof timbers for the vaulted ceiling. When fitting any steel work, safety is the key priority. Access, weight calculations and adequate, experienced man power are essential when fitting beams. We supplied a crane to enable us to fit the majority of the beams, due to the access and weight. Crank beams have to be profiled so the angles fit perfectly with the roof and all steelwork needs to be surveyed to be millimetre perfect. We have under taken various projects with intricate structural designs. This experience enables us to survey and carry out the project in a safe manner, ensuring the original building isn’t put under any undue stress.

Energy efficiency

Insulation is a vital part of any modern building. Well fitted insulation will cut down on heating bills and regulate the temperature in hot and cold conditions. Celotex insulation was fitted within the roof timbers. Foil space blanket insulation was then fitted throughout the underside of the vaulted ceiling area, ensuring that there were no cold spots. The floor area (over site) was also insulated with Celotex insulation and underfloor heating was then fitted, providing an efficient even temperature.

Modern open interior

Two sets of aluminium bi-folding doors were supplied and fitted along with an aluminium shaped gable frame above the bi-folding doors. This provides fantastic light and panoramic views to the extension and also gave the building a wow factor.

An office mezzanine was created on the first floor, above the original double garage. The office benefited from the stunning views enabled by the aluminium gable frame but didn’t interfere with the atrium ceiling detail. Stainless steel and glass balustrades were fitted to complete the modern design.

Tight management for a great result

The build was managed from start to finish to a build and budget schedule. Regular build and design meetings with the client, architect and engineers enabled us to understand and deliver both the practicalities of the build and the design vision that the client required. This led to a stunning build and finish.

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