Damp and mould
Track down the causes of dampness at your place – it could be an easy fix.
How to clean mould from a wall
We recommend using meths rather than bleach, vinegar or commercial mould removers. For mouldy fabrics, try dry cleaning – or it’s off to the textile recycler.
Easy ways to reduce dampness
Things you can do to stop excess moisture encouraging damp and mould.
- Air your home regularly. Open doors and windows for 10-15 minutes each morning, or use a ventilation system.
- Use energy efficient, low emissions heaters. Heat every room being used by someone to at least 18˚C. Don’t use unflued or portable gas heaters.
- Dry washing outside. Use a washing line or rack under a covered verandah, garage or carport. To be Gen Less, use a clothes dryer only to finish them off, or if it’s raining.
- Use extractor fans. They can help to get rid of moisture in the bathroom and laundry, and use a fan or rangehood in the kitchen.
- Turn on the bathroom fan before a shower or bath. Shut the door and open the window an inch. Afterwards, leave the fan running until the moisture clears.
- Use lids on pots when you cook. This helps to stop the steam escaping.
- Move furniture away from walls in winter. A 10cm gap will discourage mould (especially on external walls).
- Leave wardrobes slightly open. A little air circulation discourages mould growing on fabric.
A solution for damp days
Extracting moisture from the air with a dehumidifier helps to reduce condensation but it won’t solve a dampness problem. It’s better to tackle the sources of damp and heat and ventilate your home.
Find dampness problem areas
A checklist of places to look for the source of damp problems.
- Your clothes dryer, rangehood and extractor fans should send air and moisture to the outside, not inside or in the ceiling space.
- Extractor fans and ducting are at least 150mm diameter – smaller ones won’t be effective (except in a toilet).
- Ducting isn’t damaged, and is short and straight as possible – it’ll perform better.
- Extractor fans and rangehood filters are clean.
- Plumbing pipes and services have no leaks and no moisture is getting into walls, floors or near showers or baths – get under the house if you can.
- In the next downpour, check for blocked or leaking downpipes and gutters, and make sure downpipes connect to storm water drains.
- Subfloor walls vents are unblocked and the subfloor area is clear.
- There are no leaks in wall and roof cladding and flashings.
- Concrete walls and floors (lift the flooring) have no damp patches or white mineral deposits which indicate moisture is coming through.
The little device that can help you find problem areas
Use a hygrometer – a low-cost digital device you can buy online – to check room temperature and humidity over a few days (especially in winter). If the temperature is below 18˚C and the humidity regularly over 65%, the room is too damp to be healthy.
A list of thing to fix, install and improve to combat dampness.
- Put a run-on timer switch or humidity sensor on the bathroom extractor fan. A run-on timer keeps the fan running for a few minutes after you switch it off. A humidity sensor turns on the fan when it detects steam.
- Install a shower dome. This will stop steam escaping into your bathroom.
- Buy a bed base. If your mattress is on the floor, get a bed base so air can circulate underneath.
- Improve drainage. If surface water flows under your house during heavy rain, reshape the outside levels or install drainage. Ask a licensed drain layer for advice.
- Install subfloor vents. Your house should have subfloor wall vents on all sides. Ask a qualified builder for help on sizing and/or installation.
- Seal damp concrete or masonry. Use a waterproofing sealant or moisture barrier. Ask an expert about the best product for your situation.
- Get moisture content professionally measured. Hire a registered or accredited building surveyor to measure the moisture content of your home’s materials – often the easiest way to find hidden leaks.
- Install a ground vapour barrier. Thick polythene sheeting installed on the ground under your house keeps moisture in the ground and stops air under the floor from getting damp.