Extensions & Renovations For Semi-Detached Houses

Renovation ideas for semi detached houses

Urban life of the inner city suburbs of Sydney has a certain kind of energy and buzz about it. Each suburb, or village has its own character with appeal to a whole range of families with varying lifestyles.

Part of the appeal of bustling suburbs like Erskineville, Randwick, Leichhardt and Waverley is due to the cute semi-detached houses with their heritage street fronts and low maintenance, smaller-sized blocks of land.

However this style of house often needs modification to make it suit the modern family’s lifestyle. Semi’s are often dark and somewhat cramped by today’s standards, yet they have huge potential, and by using clever design you can end up with well-conceived alterations and additions that fit your lifestyle and your family.

The only way is up

The challenge with undertaking renovations on a semi is to incorporate the style and layout of the existing building on a very limited footprint. When done well, renovations combine the charm of traditional buildings with the conveniences of modern living. The aim is to maximise the living and storage areas, while providing a sense of open space.

Often there is not a lot of natural light in a semi so a key goal is to bring in as much light as possible while creating more liveable space.

If you need more room but don’t want to extend outwards, extending upwards is your best option. A first floor (second storey) addition can be added to most houses and for less than you might think.

First floor additions are perfect for adding extra bedrooms, creating separate living spaces and are ideal for growing families. Almost 20% of all Addbuild projects are first floor additions to semis in the Inner West such as, Rhodes, Leichhardt, and Marrickville, near the Airport, Erskineville and other inner city areas. Plus, a number of Eastern Suburbs areas such as Waverley and Randwick.

We’ve put together some points to consider prior to commencing the journey to renovating your semi, or buying one of your own.

Common reasons for choosing a first floor addition:

  • Needing extra bedrooms for children or extended family
  • Needing a second living space separate to the main living space
  • No room to extend at ground level – the case with most semi’s
  • No need to give up any of your already limited outdoor space
  • Need for extra storage space
  • Wanting to connect the indoors with the outdoors for entertaining

Aesthetics – the streetscape

When designing your new addition, you will need to consider the streetscape. We have design consultants that we engage because they are experienced in designing additions to semi-detached houses and work to create a subtle design that is sympathetic of the streetscape and local heritage style. For example, the most successful designs with many local councils, are those that build beyond the ridgeline.

Get the design right the first time

Once you have decided you want to renovate, you need to get a design approved. However, keep in mind, getting a house addition designed, and the concept approved by the council is only 50% of the process.

The rest of the process is getting that plan to a point where it is buildable, liveable and certifiable. We confidently use designers that have experience enough to design your addition so that it is what you want in your home and it is also a home design that your council will approve, and something that when actually constructed – meets the Government Building requirements.

In some cases you can get a plan through council but that doesn’t necessarily mean that it will pass the Australia Building Certification once it has been built to obtain the Occupation Certificate at the end to allow you to live in it.

There are few companies that truly know how to do that successfully. Few builders have the experience of creating first floor extensions and additions on semis, and know how to do that successfully, whereas we have over 40 years experience.

We prefer to work with a client from the very beginning, however we also work with clients that come to us with plans already drawn. At the beginning we can understand your needs and your lifestyle, and apply our expertise and knowledge to design you something that you can build knowing that it will be liveable, enjoyable, and ultimately approved by the building certifier.

Extensions for semi detached house

Unique aspects to your design

In some areas of the inner west, that are more directly under the flight path, a noise report needs to be obtained. In response to that noise report we determine which, if any, special materials need to be used to minimise aircraft noise and adhere to council requirements, plus the Building Code of Australia.


During the construction phase of an addition to a semi-detached house, you need to consider is the access the property by your builders and tradespeople, during the construction period. Materials can be brought in through the laneway if there is one (most semi’s have a small laneway to the side of up to 1metre wide).

We often take construction materials down the long narrow hallway of the semi, and look closely at the surrounding streets to manage parking and access to the property. Recently having completed a project in Lewisham on Parramatta Road, we made sure we understood each council’s specifications and requirements to ensure our tradesmen were safe and also able to obtain access to the property when they needed to.

The neighbours

Having your neighbor on side can be very important as a part of the whole renovation process. Consider the impact on your neighbours of the process of building an addition, and if you already have good relations, discuss the idea with them. Possibly even invite them to renovate their semi in unison.

On occasion, we get asked to build additions for a double-semi where 2 neighbours want to adhere to the same aesthetic, or the owner owns both sides – as we did recently in Randwick and Manly – however it is usually the 1 neighbour of the pair that intends on building at a time.

The common wall

The unique challenge with owning and renovating a semi is considering the easement, or common wall that separates your home with that of your neighbour.

As it is law that you can’t build over common property, this requires a system for creating a stable addition to a building that has a common wall, without encroaching on the neighbours and their property.

Over that last 40 years we have developed a strong and stable system for ensuring we don’t rely on the parting wall for support and use our own strong brick support.

To stay or to go?

Something to consider is whether or not you choose to move out during the period of construction and lease a property nearby (or stay with relatives), or to stay in your home during the period of construction.  Over 80% of our clients tend to stay in their homes throughout the process however every addition design, and every family are different so some thought needs to be given to how this would impact your family.

Read our ‘Consumer Guide to Home Improvement for more details and think about what you would want to do when you renovate your semi and give us a call to talk about what we can do for you.