Household Mold De-Mystified

Mold are asexual fungi. They reproduce via spores which are small enough to be easily carried in air currents. As a consequence, mold is virtually everywhere. It’s not a question of whether there’s mold in a any given house; it’s a question of how much. As a home inspector, I know my clients are concerned about the levels of mold in the house they are considering buying, but determining the quantity, variety and measures to be taken for remediation are beyond our standard of practice. In fact, we even resist using the term ‘mold’ before the buyer has test results in hand. We will however raise questions should it become apparent that further investigation is warranted. Specialists can come in to take samples for examination at a lab.

Attic hatch seal Basement wall
Air leak at attic hatch Damp floor wicks up wall
Discoloured roof sheathing Toilet condensation
Poor ventilation in attic space Condensation from toilet
Wet bedroom wall Wet subfloor around toilet
Wet bedroom wall Wet subfloor around toilet

Buyers and agents often focus on the suspected mold as the problem. They worry about the health risks of exposure and allergic reactions. Legitimate concerns, but they need to understand that mold is actually a symptom of other underlying problems. For mold colonies to grow they need four things: a few spores to seed the colony, organic material to feed upon, moisture at suitable temperature and time to sporulate or reproduce. Our homes are full of organic materials like, wood framing and trim, paper coatings on drywall, exfoliated skin cells and soap scum in bathroom fixtures. We can’t eliminate these materials, nor change the temperature range we maintain in our housing. The factors we must control are the presence of moisture and how long it remains. Without fail mold colonies are found in moist environments.

Home inspectors are trained to look for signs of discoloured building materials in damp areas. Attic spaces are susceptible due to high humidity levels if ventilation is poor or through other poor building practices such as terminating plumbing stacks or ventilation ducts inside the space. It happens more that you would think. That moisture produces black patches that can cover the entire underside of the sheathing. Long, hot showers without turning on the bathroom fan can trap a lot of moisture in a home. Condensation from toilet tanks and leaking seals can be a source of moisture that rots wooden floor sheathing. Blocked clothes-dryer vents are a common source of humidity. Basements are particularly susceptible for a number of reasons, not the least of which, is that water will run to the lowest level it can. Less obvious sources are back-drafting furnaces and gas water heaters that can produce large amounts of humidity, not to mention deadly levels of carbon-monoxide. Unfortunately we can’t tear things apart to look for problems inside walls so there’s a limit to how much can be detected visually.

Modern homes are designed to remove as much excess moisture from a home as possible. Improved attic-space and bathroom ventilation, damp-proofed foundations, weeping tiles, floor drains, sump pumps and heat recovery ventilators are all innovations designed to control interior moisture levels. Humidity can vary greatly but as long as high levels are brought under control relatively quickly (under 48 hours), mold doesn’t have the time to sporulate and its growth is curtailed. So the best strategy is keeping things dry and if a mishap occurs make sure it gets taken care of in short order.

Mold is a surface phenomenon. Test kits are available if you want a lab to pin down specifically what you are dealing with. But in general if it smells funky, it’s there somewhere. If you recognize a small problem area early enough you can clean it up yourself with soapy water or by wiping with alcohol. This won’t address any staining but it will kill the fungi. Dead spores are just as toxic as live mold so get rid of any rags or sponges used in the cleanup. Anything very extensive will require professional removal or remediation, but this can be a significant cost. So get a handle on any problems early on and remember that any repairs you make to keep your home dry are helping to avoid major expense and potential health issues later.

Author: Rob Cornish is a Home Inspector in Ottawa, Canada. © 2013 HomeXam Inc.
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