Mould problems and DIY Mould Solutions
Our house, extended a few years ago, sits on a sandstone outcrop in a Sydney bushland setting. The position is idyllic but has some challenges, namely high humidity
When it rains the sandstone acts as a sponge to the water and that, together with the high vegetation concentration of the surrounding national parks, means we have an average indoor humidity of 70%!
The result is a proliferation of mould on windows and the surrounds. Such high levels of condensation on windows requires daily mopping and a dank odor reminiscent of an old English stately home.
We had also put in wooden flooring and the high humidity actually caused the wood to swell with the floorboards lifting - heartbreaking and costly.
Mould health effects
Most importantly, we have family members who are prone to allergies and the mould has resulted in a proliferation of flu like symptoms and other respiratory ailments.
There is a huge business in mould prevention and it really is worth spending the time understanding how your house works, as if the mould problem it is allowed to get out of control it is both costly and will make your family very ill.
This is what we have done to manage the mold problem without outside intervention:
External measures to reduce humidity and mould problems
- We inspect the substructure of the house every time we have significant rain. We were absolutely amazed to find that we actually had flows of water under the house (check up to 2-3 days after a downpour as the sandstone needs to be saturated before you see any excess flow). Given that we sit on rock and we are in a hollow we get everyone's rain.
To counter this problem an agg line had been placed both on the external and internal perimeter to provide a mechanism for water to flow away. A pipe was then fitted to take the water out of the building framework. The brick walls and pockets of clay actually created a dam effect which had knock on effects on humidity and mould build up.
- Additional air vents to the sub-floor were also put in to increase ventilation. We also experimented with fans to dry out the air.
- Where we have a crawl space i.e. under the area where the floorboards lifted, we have made efforts to increase the size of the cavity through the removal of mud plus we have covered the ground area with a very thick impermeable plastic sheeting to reduce the interface to the ground.
- All wood chipping/ vegetation based mulch around the perimeter of the house has been removed as this harbours mold spoors.
- Maintain all storm drains around the property to get rid of water fast.
Internal Measures to reduce humidity and hence mould
- Monitor the relative external humidity and internal humidity. It is worth investing in humidity meters for key rooms so you get an idea what is your norm.
As a rough guide you do not want to have humidity higher than 70% as you will actually have a damp environment; mould loves dark/damp conditions.
- Only on days where your external humidity is lower than your internal humidity - open your windows and ventilate your home for as long as you can and as often as you can.
- Invest in a good dehumidifier and run it during off peak electricity times, ideally overnight. This really works to drop the humidity. In winter we run it nightly.
- Keep your windows clean. Every fortnight spray the glass and surrounds with a dilute solution of vinegar with additions of clove oil to inhibit mould growth. As a last resort use bleach as it gets rids of the staining but the vinegar is a better at killing the mold spores. A new eco mould cleaner containing lavender is now on the market so you could try adding lavender to your vinegar mix.
- Dust your house weekly as this is where mold spore multiply.
- Hover rugs/carpets at least once ideally twice a week to remove dust including mold spores.
- Make sure your clothes dryer is vented to the outside.
- Minimize the drying of clothes inside.
- When using the shower make sure you run the fan prior to and at least 5 mins after your shower to dissipate the steam. Keep the doors closed to the bathroom.
- When cooking use you ventilation system again to get rid of the steam which contributes to your humidity.
- Realize that the use of gas and open fireplace plus indoor plants all increase indoor humidity.
- Once a week spray rooms with an anti mold disinfectant spray e.g. Oust
- Open all curtains to increase the light to rooms as this inhibits mold growth.
- Keep a close eye on cupboards.. Use water absorption crystals to reduce humidity and watch for mold on leather items. Clean affected leather items with a very dilute solution and them dry them in the sun to kill of the mould. Dust the bottoms of cupboards.
- Use mould inhibitors in paint that are to be used in bathrooms.
- Where mould has grown on kids clothes frankly I have thrown them out as it is just not worth the risk.
Doing all of the above we are able to manage the environment and control the humidity. If I saw mould appearing on walls or ceilings I for sure would be calling in the specialists.
Systems that help manage mould
You could also invest in a home ventilation system to move filtered air from your roof space into the living space, this changing of the air reduces the humidity that often accumulates in a house, so thereby reducing the occurrence of mould. They can also provide heating and cooling benefits.