FAQ's for a basement renovation in Australia

ARTICLE Carol Watson

Do I need approval to convert my basement into a living room or bedroom?

Yes, you need approval to convert a basement into a habitable room. Any basement conversion will usually involve excavation, and significant changes to the structure of your home, which must be approved by Council.  

How can I maximise the use of the small space under my house?

By extending beyond the boundaries of your house and doing an open excavation into the garden, you can create a larger basement area. Whilst Council will look favourably on a conversion within the existing boundaries, it’s worth going through the process of approval for an extended boundary if the end result is a larger space that can be used for multiple purposes.

How can I ensure the foundations of my house won’t be compromised during the excavation process?

Prior to excavation the sub floor will usually be supported with brick piers followed by the installation of a loadbearing steel framework. The existing floor framework will remain in place so this should ensure that your home remains secure during the build. Choose your tradespeople wisely and ensure your engineer and builder have sufficient experience and expertise to do the job.

Do I need to waterproof my new basement?

As basements are below ground level, water will naturally enter a building through the walls. You need to waterproof the basement by sealing the walls using a surface coating. This process is known as tanking. It does not remove the water but creates a barrier between the wall and the water. Another option is to install a waterproof studded membrane system. This allows the water to run down to the floor within a created cavity and into a drainage system. The water will then flow away naturally or can be removed using a pump. An alarm on your pump will emit an alert if the system fails ensuring there is no prolonged outage period, which could otherwise go unnoticed and cause significant water damage.

How can I ventilate my basement to prevent a build up of mould?

Ventilation is one of the most important factors for a successful habitable basement. Use the available natural ventilation by installing windows that can open and close, preferably opposite each other to allow for cross ventilation. Mechanical ventilation can be achieved through the installation of an exhaust fan to remove moisture and pollutants from the air. These fans often come equipped with a humidity sensor that will activate the fan when moisture is detected. Ensure the fan is vented to the outside of your building. 

How can I get adequate light into my basement?

If your basement opens out onto your garden, install floor to ceiling sliding or bi-fold doors to let in natural light. If your basement is surrounded on all sides by soil you can install solar tubes to channel natural light into the room. An open plan basement with fewer dividing walls will aid the flow of natural light throughout the space. Select a light colour palette when painting and decorating. The use of a large mirror to reflect light will also contribute to a brighter and inviting space and reduce that feeling of a closed in bunker.

How long would a typical basement conversion take to complete?

It can take a number of months, but depends on the size of the basement. There is significant time spent on underpinning, excavating and ensuring the area is watertight. You are making significant changes to your home, so allow adequate time to ensure the work is done properly and meets the standards of the Building Code of Australia (BCA).

I plan to convert my basement into a media room. Is this a wise decision?

A basement is a perfect location for a media room. Ambient light is often reduced under the house and the area tends to be cooler than the upper floors of the house reducing the need for air conditioning in the hot summer months.

Are there any requirements I need to address in relation to a fire exit?

If the basement is to be used for habitable purposes, an external door or window suitable for egress is required. Alternatively, a protected stairway leading from the basement to a final exit must be installed.

Are there regulations about the ceiling height of my basement room?

The height of the ceiling must be sufficient for the intended use of the space. The Building Code of Australia (BCA) sets out the required ceiling heights. The minimum ceiling height for a habitable space, excluding a kitchen, is 2.4m whilst a kitchen, storeroom, laundry or bathroom need a minimum of 2.1m.

We live in a terrace house. Can we do a basement conversion?

Yes you can, but your must address the implications of the excavation on your neighbours. Terrace houses include party walls, or walls that are shared between you and your neighbours. Before you do any work you must have the consent of your neighbours.

Do I need to move out of my home whilst my basement is being converted?

This will depend on access to your basement. If there is free and easy access, via the garden or a neighbouring pathway, then it may be possible to stay. If you do move out, it is wise to be on-site on a daily basis to deal with any decision-making and questions that may arise.

Also have a look at How much does an excavation renovation project or basement conversion cost in Australia?  

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*All information is believed to be true at time of publishing and is subject to change.