Noise control, moisture control and ventilation

Building Code requirements for noise control

Building Code Clause G6 Airborne and Impact Sound provides for the control of noise transmitted into the habitable spaces of abutting household units. Its objective is to 'safeguard people from illness or loss of amenity as a result of undue noise being transmitted between abutting occupancies'. The Approved Document provides limits on the noise received from outside the household unit and noise within the house, such as creaking floors and the activities of people, by giving minimum performance levels for walls, floors and ceilings.

The Australian/New Zealand Standard AS/NZS 2107:2000 contains recommendations for sound levels and reverberation times inside buildings. Your designer should know what is required to meet Building Code requirements.

Methods of managing noise

One way of controlling noise nuisance is by house design, for example, placing the rumpus room and utility rooms like kitchens and laundry away from the quiet rooms such as the study and bedrooms. Buffer zones, such as hallways or cupboards, are another means of noise transmission control. The impact of noise from outside, such as from traffic and neighbours, can be minimised by designing the layout so that rooms which should be quieter are furthest from the noise source.

Other methods include:

• Using wall boards with noise control properties.
• Insulation usually also helps control noise transmission.
• Carpet and underlay on an upper floor help deaden sound.
• Flooring designed to control noise.
• Noise control glass.
• Insulation around plumbing pipes.
• Seals around doors.

The effectiveness of noise control materials will be reduced if there are gaps, for example, under doorways, or through downlights and power outlets.

Controlling moisture build-up

Moisture accumulates in the house from people bathing, showering, cooking, breathing, and watering plants. It also comes into a home from outside. Some appliances, such as unvented gas heating, clothes dryers, dishwashers and washing machines also produce excess moisture into the air.

The moisture builds up quickly and is worse in modern homes which are built to be almost airtight. On cold days you can see the moisture when it collects on the windows as condensation. It is also absorbed into fabrics and building materials. The problem with this moisture build-up is that it can cause mould and mildew on walls and fabrics, which is not only unsightly, but can trigger allergies. For example, dust mites - the source of one of the most powerful biological allergens - thrive in damp conditions.

If you are building a new house, there are a number of chemicals and resins present in many building materials which continue to leak into the indoor atmosphere for many months after you move in. This can be managed with good ventilation.

The options for managing moisture are:

• Good ventilation.
• Window joinery with built-in drains - that allow condensation to drain to the outside.
• Keeping the house warm and dry through heating.
• Extraction fans in bathrooms and kitchens.
• Good insulation to keep the home warm and reduce condensation and mould growth.

Options for ventilation

Ideally the air in a home should be 'renewed' every two hours, even when you are not at home. Some simple options are to fit aluminium windows with passive air vents or to fit security stays that allow the windows to be left ajar. When windows and doors cannot be left open, consider mechanical ventilation systems and air conditioning systems:

• Positive pressure or forced air ventilation systems work by blowing drier air into your house from the roof space above the ceiling or, in some types, from outside. They suit older houses with wooden joinery better than modern houses with sealed aluminium joinery – unless windows are opened or additional vents fitted.
• Balanced pressure / heat exchanger ventilation systems extract warm damp air from living spaces and pass it through a heat-exchanger to heat up dry air which the system brings in from outside. This can fully meet Building Code requirements. They work best in more airtight, modern homes.
• Extractor fans are used in places like the kitchen and bathrooms to remove steam.

Which system is best?

This depends on the design of your house, its floor area, the location, how much sun the house gets, the type of roof ... even the local climate.

Before you install any system, do some homework. We've outlined how the different designs work and some of their pros and cons which should help you decide whether your house is suitable for any of the systems available. Consider what you want to achieve against the types of system – and also look for any extra features you might need to meet your particular requirements.

For best results, a system should be designed specifically for your house and your needs. But this can be quite costly, especially if you choose a fully automated system with multiple outlets or other options.