This copy is for your personal non-commercial use only. To order presentation-ready copies of Toronto Star content for distribution to colleagues, clients or customers, or inquire about permissions/licensing, please go to: www.TorontoStarReprints.com

Every house in the world has at least a little mould somewhere. The question is, does mould matter? And if it does, how best to get rid of mould once and for all?

Mould is a necessary part of any natural ecosystem. It’s the life form that breaks down organic matter for reuse later by other living organisms. Trouble is, mould breakdown is not something you want going on in any part of your home — natural though it may be. There are three reasons why.

Besides the fact that mould looks ugly, it can sometimes be a health hazard. Sometimes, but not always. Contrary to popular fears whipped up by overzealous litigation lawyers, not all moulds are harmful. In fact, many are not. But how can you tell bad mould from harmless mould? Unless you’re an expert you can’t, and that’s one good reason to get rid of it on sight.

Structural decay is another reason mould has to go. Like I said before, mould indicates the first stages of natural decomposition, and while things need to get pretty mouldy in a house before significant physical damage sets in, it’s always best to eliminate mould issues the first time you notice them.

The main thing to understand about mould is that it can’t grow without sufficient moisture. Any material will remain mould-free forever without moisture, and almost any surface in your home can grow mould if it’s kept wet enough for long enough. All this is why the first step toward mould control is moisture elimination.

Although mould can grow in many places, there are three locations you’re most likely to find it in your home: frames on windows that get wet each winter from condensation; drywall and wooden wall frames that get wet periodically in basements and bathrooms; underneath basement carpets; and any area that stays wet because of flooding or leaks.

Exactly how you eliminate moisture varies with each circumstance. If your windows get more than a little wet during cold winter weather, open more windows or get a heat recovery ventilator to drive interior humidity levels down. If your bathroom grows mould on the ceiling, install an exhaust fan or get a more powerful fan than you have now. If your basement carpet smells musty and grows mould underneath from invisible moisture vapour moving up through the concrete, replace the infested carpet with something else installed on a moisture-proof subfloor. Got cardboard boxes on your basement floor? Get them up on shelves. Cardboard is such an attractive food source for mould that it only takes a little bit of moisture to start things growing.

Mould control in situations like these are mostly simple, do-it-yourself things, but there are two situations where mould control should be handled by experts.

If the mould area you’ve got is larger than a bath tub or two in size, or if it’s been caused by a sewage leak, get professional help. Although this is wise for health and safety reasons, cases like these are rare. You can handle the vast majority of household mould issues yourself, as long as you know how.

Eliminating moisture and mould food sources is one thing, but sooner or later mould control eventually comes down to killing the stuff. Even if you do keep surfaces dry, who wants dormant, ugly mould remains just sitting there? Besides looking terrible, mould that’s not been properly killed is always ready to spring quickly back into action at the slightest bit of moisture. What most people don’t realize is that the usual way of killing mould is neither effective nor particularly safe.

Bleach and water solutions have been recommended for killing mould as long as anyone can remember, and though it’s extremely cheap there are two problems with it. Besides the fact that bleach is an irritant and toxic, it only works to kill mould reliably on hard, non-porous surfaces. That’s because of the way mould grows.

One of the hallmarks of all species of mould is the way it sends root-like structures into anything that’s even remotely porous. Surface tension prevents bleach from fully penetrating these porous surfaces, resulting in a superficial mould kill only. The roots survive and the material remains inoculated, ready to start growing mould again quickly in response as soon as threshold levels of moisture are reached again.

Killing mould deep down is something that few products can do, but the best I’ve seen in my field tests also happens to be Canadian. I first tested Concrobium Mould Control in 2005 (concrobium.com, 1-866-811-4148) and find that it works amazingly well. It’s an odourless liquid that’s completely safe and works without toxins. Instead it kills mould and mould spores by physically crushing them as the liquid dries. Concrobium also provides residual anti-mould action, which is something that bleach doesn’t do.

Earlier this year I tried a new product from Concrobium called Mould Stain Eraser. It’s a two-part powder that you mix with water. Let the mixture sit for 10 minutes, then brush, swab or spray it on any area that shows mould staining. Without any scrubbing, all stains disappear within 10 minutes. You can actually see the staining disappear as you watch.

Although Mould Stain Eraser isn’t sold for brightening wooden decks, it performs better than any other deck brightener I’ve tested. It changes dull, grey, weathered wood bright and new in about 15 minutes, all without scrubbing or sanding.

Like many things in life, controlling mould isn’t just a matter of applying some magic product to the problem. Although proper mould control supplies are part of the solution, solving the root cause is what makes permanent gains happen.

Steve Maxwell, syndicated home improvement and woodworking columnist, has shared his DIY tips, how-to videos and product reviews since 1988. Send questions to steve@stevemaxwell.ca , connect with him on this website stevemaxwell.ca, on Facebook at Canada’s Handiest Man or follow him on Twitter at @Maxwells_Tips.

Anyone can read Conversations, but to contribute, you should be registered Torstar account holder. If you do not yet have a Torstar account, you can create one now (it is free)

Copyright owned or licensed by Toronto Star Newspapers Limited. All rights reserved. Republication or distribution of this content is expressly prohibited without the prior written consent of Toronto Star Newspapers Limited and/or its licensors. To order copies of Toronto Star articles, please go to: www.TorontoStarReprints.com