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Balgowlah Renovation & Extension

Seaview St, Balgowlah

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Our clients Daniel & Carol first engaged our company to discuss their project in June 2020. Daniel and Carol were seeking a builder who could achieve the high-level finish required of the design and the overall complexity of the scope of work.

This project consisted of a ground-floor extension to an existing semi-detached home in Balgowlah, Sydney. This existing semi-detached home’s history can be traced back to the early 1900s when it once served as a lunch room for the local railway staff. The railway staff were able to easily access the lunch room via a set of concrete stairs and entry on the side of the home. Sadly, these stairs and entryways have been removed as part of the new home extension and design.

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"To emphasise this beautiful indoor/outdoor seamless living space, the clients chose to have polished concrete floors making the space breathtaking."

This extension is made up of a new open-plan living space, a new kitchen, new laundry & bathroom. There are some absolutely stunning design features inside the new home including a vaulted ceiling with a ceiling height of more than four metres, polished concrete stairs and living room floors, an oversized pivot door (the largest I have ever seen) measuring 3.3m high x 2.5m wide which has been set flush with the internal polished concrete floor finish.

The new living space is set to level with the backyard allowing the homeowners to move between their new rear alfresco area and living space effortlessly. To emphasize this beautiful indoor/outdoor seamless living space, the clients chose to have polished concrete floors on both the internal living space as well as the external alfresco area; making the space breathtaking.

The entire home has been landscaped using only native plants and included in the landscaping scope of works was the construction of a cedar shed for the client’s gardening equipment.

The architect’s selection of internal finishes is minimal and contemporary. For this project, the architect opted out of having architraves and instead the doors and windows are set proud of the wall linings by 5mm. The skirtings are also unique and are set flush with the wall linings.

Considering the level of detail specified within this project it was inevitable we would encounter some challenges along the way. We love problem-solving at AAG and have outlined the main challenges faced below:

1. The combination of polished concrete floors without skirtings or architraves meant that there was no tolerance to work with during setout. With these strict parameters consideration to these details needed to be given early in the project; so early in fact that our team was setting out the location of wall lining thicknesses prior to any structure or concrete slab having been poured or built. AAG Project Manager Adam spent many late nights on Google Sketch Up ensuring that the site setout was spot-on from the get-go.

Due to the meticulous setout completed early on in the process, we were able to order all the structural steel, doors and windows at the very start of the project so the project didn’t miss a beat and so that the construction timeline would be as short as possible. The installation of the steel, doors & windows went flawlessly and the end result was perfection.

2. Lower level floor level incorrect: During the site set out it became apparent that something was amiss. The architectural plans showed the floor height approx 600mm above the natural ground level which contradicted the structural plans which specified a slab on the ground.

If we built the new extension to the height specified the result would be a 600mm high thickened slab edge(exposed). In addition to this, we would need a redesign of the structural concrete works to include a waffle slab.

It was our advice to the client to obtain permission from the Certifier to change the floor level which would have the following advantages:

  • Increased room height
  • Increased door size
  • Aesthetically pleasing polished slab on the ground
  • No need to change the structural design
  • Speed of outcome


The disadvantages were:

  • Construction of an additional two steps inside the home to bring the clients down from the kitchen to the new living room would be required to absorb the new height difference.
  • The length of the concrete stairs encroaching into the living space became greater. These stairs also needed to be incorporated into the adjacent joinery detail.
  • The increased height of the TV joinery creates some cupboard space that may be difficult to access.


The client agreed with our recommendations, and the required permissions were obtained from the Certifier. The end result was fantastic – the alfresco polished slab is nearly flush with the level backyard, which looks beautiful.

The change in the internal stair design became a great feature that the clients love and they have since told us they can’t imagine it any other way. Additional storage space is obtained in the TV joinery, and although this space is difficult to access it is now used for suitcases that are used infrequently.

3. Boundary Wall Gutter System: As the project approached the frame stage, a missing detail became apparent: how is the roof water on the shared boundary going to be discharged?

The roof design terminated on top of the core-filled concrete boundary wall and the roof and gutter design detail ended here. As this new boundary wall needed to be fire rated, the new gutter system on top of this wall would also need to be fire rated.

This issue was resolved through site meetings with the hydraulic engineer, architect, builder and certifier. This is a perfect example of where good communication and collaboration are so essential within the building game. The end result was the construction of a fire-rated timber framed wall on top of the concrete-filled wall which encapsulated a custom-made box gutter. The structural steel supported by the concrete wall was modified prior to installation to allow for the box gutter.

The COVID outbreak was pretty heightened at this time so we had to ensure that we were keeping both our clients and our trades safe by following the strict guidelines in place (i.e. QR check-in, social distancing, meetings via video where possible etc). In many ways, this project was amongst the more challenging projects that our company has had the pleasure of building. Considering the high level of detail and high-level finish required, this project will forever stand out amongst the rest as the most rewarding.

We are proud of the beautiful finish of this build and the work from our AAG team on this build. The end result reflects the attention to detail that we pride ourselves on. From the beautiful clients, we had the pleasure of working with to the beautifully designed home created by “Those Architects”, projects don’t get much better than this one!