Building extensions at home

The decision to go up or out when extending your home can be a tricky one when building extensions. Backyard space, views, ageing family members, resale value - they're all relevant issues to be debated, deliberated and eventually built on.

Victorian manager of Archicentre David Hallett says broad considerations include the structure and position of your home, cost, design and planning controls. Sensible design, construction and material selection are imperative.

"Structurally, building a floor on top of an old floor may require reconstruction of the old floor," David says. "This process can be minimised if the upstairs structure is a lightweight construction system, for example weatherboard. However, if there's brickwork on the upper floor, a steel structure on the ground floor will be required."

Planning the relocation of home elements during extensions

First-storey extensions will also impact on the ground floor in terms of staircase or wall relocation. Existing chimneys, heater flues and exhaust fans, range hoods and skylights may need reorganisation or diversion too.

"Building height is another consideration, as adding a floor on a sloping block can easily exceed building regulation height limits, so it's important to be careful with the roof form," David says.

Building extensions in heritage areas

Alterations visible from the street are a difficult option in heritage areas. Impact on neighbouring properties, for example space and privacy, is another often-overlooked consideration in extending upwards. For this reason, it's wise not to assume you'll get a permit - early concept planning will determine the feasibility of your project.

And then there's the cost. The average first-storey renovation will cost about 10 to 20 per cent more than a ground-floor extension. However, you may decide the cost is offset by the increased value of saving your back garden and outdoor living area, perhaps even adding a deck, paving, pool or spa.

Go out with extensions rather than up

Architect Stuart Vokes, of Owen and Vokes in Brisbane, believes moving sideways is always a better option if it can be done. "People have a predilection for rooms close to the ground," he says. "Extending upwards can create disengagement between living areas and the garden, while sideways extensions retain proximity to nature." And there's also the issue of ageing occupants' ability to manage those pesky stairs.

If you do decide to extend upwards, deciding who'll go up there is critical, as it will impact on planning and style. For example, if upstairs is to become a parents' retreat, it will likely be smaller than a kids' or study/living area and therefore influence the style and shape of the addition.

Contact a builder to find out more about building extensions on your property: