Keeping your home free from mould

‘‘The link between damp and mouldy homes and poor physical (and mental) health has been well established.’’

New houses are snugger than ever before, thanks to the increased use of aluminium joinery and sheet linings for walls and ceilings.

But while draught-free homes are good in many ways - they also come with a downside: a tendency to mould. New research shows that over half of Kiwi homes homes have visible mould.

As well as having more airtight homes, the research undertaken by BRANZ (Building Research Association of New Zealand) shows that homeowners are compounding the problem by being hesitant to open windows and doors, or operate extractor fans in the kitchen and bathroom.

This reluctance comes from fear about security, the necessity to control utility (heating) costs or a desire to keep warm air inside.

In addition, many New Zealand homes tend to be underheated, or heated only in the morning and evening when people are home.

These three factors - airtightness, poor ventilation and variable levels of heat, particularly during the winter and as the seasons change - create a perfect scenario for internal condensation and mould. Five years ago, the 2010 BRANZ House Condition Survey showed that damp and mould was a common occurrence in New Zealand homes.

Preliminary results from the 2015/16 survey suggest that mould is visible, to some extent, in over half our houses; with the problem worse in rental properties. The link between damp and mouldy homes and poor physical (and mental) health has been well established and BRANZ are urging builders and designers to do their bit to overcome the problem.

According to BRANZ, industry professionals can do their bit in a number of different ways. Designers should try to lay out living and sleeping spaces in a new home so that sun is maximised in winter and minimised in sum- mer. This can go a long way toward reducing extreme fluctuations in indoor temperatures.

The thermal performance of homes can be optimised by installing higher levels of insulation, including window frames and double-glazing. Source-specific moisture can be mitigated by active ventilation systems, such as rangehoods in the kitchen and extractor fans in the bathrooms.

Whatever the age of a home, some of the major sources of indoor moisture are directly related to the daily activities of the occupants.