How to prevent mould after your house floods

No matter how well-built, our homes can’t always stand up to the destructive power of water. Water carves riverbeds through rock and washes entire communities away in floods. It can also bring another unrelenting force into our homes: mould.

Moulds exist everywhere, often beneficially, in the environment. But unchecked, mould growth in our homes destroys building materials and can cause health problems like asthma, particularly in the immunocompromised.

“Mould can grow in as little as 24 to 48 hours given a food and moisture source,” says Michael Rubino, author of The Mould Medic, an Expert’s Guide on Mould Removal and founder of HomeCleanse and Change the Air Foundation. That’s why it’s important to act fast, if you can do so safely, to prevent mould from establishing after a flood.

“Properly addressing and drying out a space after a water-related event” will help prevent mould growth, says Rubino. Moulds thrive in damp places with lots of organic material, and flooded homes fit the bill.

Once moulds find a suitable place to reproduce, they’ll grow and not stop until you stop them. Here’s how to prevent mould from taking root in your home:

Don’t enter a flooded home until it’s safe. For a major flood event, this might mean waiting for the authorities to allow entrance. Wear long pants and sleeves, rubber boots and gloves. And, bring a change of clothes. Mould spores cling to fabrics and can easily be transferred to your next destination.

Turn off the electricity if you can safely do so. Never touch your electrical panel if it means you’ll be standing in water to reach it, though. Call a licensed electrician before proceeding with any cleanup.

Generators used in the cleanup process must be placed outside and away from the home to avoid carbon monoxide exposure.

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“It’s best to stay away from fans while trying to dry out a space,” Rubino says. Fans introduce and blow around mould spores and bacteria, which makes cleanup harder. Fans also won’t address the humidity, which needs to be below 60 percent to inhibit mould growth.

Rubino recommends using dehumidifiers instead of fans — just make sure it’s the appropriate size for your space. You may need more than one.

It’s okay to use fans before mould growth starts, but direct the airflow outside to avoid blowing contaminants into other areas of your home.

Learn how to get rid of rising damp.

This is a good time to start taking pictures of your home and belongings. Document the damage to your home and personal property for your insurance company, and for your own edification — floods are stressful, and you don’t want to forget what you threw away.

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“Choosing what to keep and what to throw away depends on how successfully the surfaces can be decontaminated,” says Rubino. Porous items like clothing, lampshades and carpet should just be thrown away. Contamination that gets down into the fibres of these items is very difficult to eradicate.

Semi-porous items like leather and unsealed wood should probably be tossed, especially if you have standing water, says Rubino. Even though these items look smooth, moulds send out roots, called hyphae, deep within the fibres below.

Non-porous surfaces like metal, glass, sealed countertops and finished wood can be safely cleaned and disinfected.

Physically remove all mud, debris and water-logged items. Use a wet-dry vacuum to clean as much water out of the remaining structure. Remove drywall to 30cm above the water line, and cut out all wet insulation. Cut carpeting and pads into sections, roll them up and place them in garbage bags.

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Wash and dry all remaining surfaces with soap and hot water, then follow with a sanitising solution. Use one cup of household chlorine bleach — the bottle should list a concentration between five percent and nine percent — to 20 litres water for surfaces not already contaminated by mould. Allow to air dry.

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Mould spores are tiny, and it’s impossible to see where they land and grow until you have a problem on your hands. In addition to carpeting, insulation and building materials, here are some surprising hiding places:

Particleboard furniture. The surface may look cleanable, but the porous inside is a prime spot for mould.

Toilet tanks. Rubino recommends checking toilet tanks once per month even in the absence of a flood, so clean them after a water event, too.

Appliances. Hidden areas of fridges and other appliances can harbour moulds. Clean out your fridge’s drip pan and in and under your washing machine.

HVAC vents and intakes. Make sure to have HVAC units inspected before turning them on.

If it’s been 24 to 48 hours since the flood, assume you have mould. Rubino recommends hiring a certified mould inspector before attempting remediation. Visible mould growth often isn’t the best indicator of a lurking mould issue.

If you decide to tackle the clean-up yourself, know your limits: “Anything larger than a square metre should automatically be handled by professionals,” says Rubino.

Wear an N95 (or better) mask or respirator. Wear rubber gloves and goggles to protect your hands and eyes. Follow the steps above to clean and dry your home, and toss out mouldy items and building materials.

Scrub hard surfaces with hot soapy water to remove visible mould. Follow with a mixture of one cup household chlorine bleach to four litres of water, rinse and allow to dry. Read all labels and never mix household cleaners like bleach and ammonia.

Moulds and other contaminants can cause long-term health and structural damage, so don’t risk trying to DIY if the job is too big. Mould remediation companies have the expertise and equipment to get the job done right. For sentimental items like family photos, restoration companies specialising in mould removal may be able to help.

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Source: Family Handyman