Mould Damage & Crawl Spaces Near Nanaimo, Saanich, Victoria

Rotting, decaying crawl space wood damaged over time in Gibsons

When mould and rot are allowed to grow in crawl spaces, they lead to health and structural problems that will affect the entire home.

Crawl space mould and rot is a housing epidemic across the United States and Canada that, with a small investment, can be easily avoided.

Installing a crawl space vapor barrier system in your home will protect it from most of the common causes of rot, damage, and humidity.

Installation of this kind of system usually takes less than a day to complete.

What Causes Crawl Space mould?

mould loves dark spaces, unseasoned lumber, and high humidity levels.

Because your crawl space is warmed by your home above it and the natural warmth of the ground below, it stays at about 50 °-60 ° Fahrenheit all year long.

To begin growing in your home, mould needs the following:

  • Oxygen
  • A relative humidity level of at least 60%
  • Temperatures at 40°F or higher
  • Organic material to use as food

Practically speaking, mould spores are everywhere -- no matter how clean your home is.

For rot and mould to grow on wood, the wood needs to have a moisture content of 20-29% or higher.

If your home meets all of these requirements (many do), then you have mould growing in, and damaging, your home.

Free mould Repair Quotes!

At Island Basement Systems, we're proud to offer homeowners within our British Columbia service area free, no-obligation crawl space repair quotes.

Each quote includes a professional, on-site inspection of your home, a consultation where we answer any questions you may have, and a written cost quote. To get started on your home repairs, contact us by phone or e-mail today!

Open crawl space vents allowing in humidity and water in Spring Island

Crawl space vents allow humidity, rainwater, and pests into your home.

mould & Moisture Sources In Your Crawl Space

Even in the case of dry rot, there will need to be a source of water nearby. This water can enter a crawl space through poorly designed downspouts or grading, through groundwater flooding, and/or through plumbing leaks.

mould can also grow when there's adequate moisture in the air, in the form of humidity. This moisture commonly enters a crawl space as water vapor passing through the soil or concrete. In this case, concrete will wick water and through the ground and releases it into the air.

One of the most common and avoidable reasons for crawl space mould and rot, however, are crawl space vents. In the summer, these open vents let in summer air, which is often loaded with humidity. As the air enters the crawl space, it quickly cools in this dark space. As air cools, it loses some of its ability to hold moisture, and the excess moisture is dropped on surfaces in your crawl space as condensation.

Over time, this condensation will saturate the wood in your crawl space--and mould will grow.

Still Believe Crawl Space Vents Work?

Ask yourself these questions:

  1. Are my crawl space vents drying my home when it's rainy, foggy, or damp outside?
  2. If crawl space vents work, why is my vented crawl space damp and rotting?
  3. When cold winter air is blowing through my vents in the winter, what's happening to my furnace, hot air ducts, water heater, and hot water pipes? What is that costing me?
  4. Will my open crawl space vents keep out termites, ants, mice, and other pests?

Signs Of Crawl Space mould Problems

Extensive crawl space rot damage growing in Cobble Hill

Surface mould will create cosmetic discoloration only and can be cleaned off without worry.

Decay fungi (above) will darken and shrink the wood while causing structural damage.

Signs of crawl space mould are often evident without having to enter the crawl space at all. Because air moves upwards in a home as it's heated, a vacuum is created that will pull air up through the crawl space through a process known as the "stack effect". If your crawl space has mould, you will be able to tell -- your house will smell musty, and you may even begin to feel and/or display symptoms of mould and dust mite allergies.

Additionally, as crawl spaces begin to rot and decay, the floor above will begin to sag, buckle, or become uneven. Doors may jam, mould may grow on first floor carpeting, and, in the long run, the floor itself will collapse inwards.

In the crawl space itself, warning signs include visible mould growth, musty odors, and discoloration and/or signs of water damage on the wood.

White, powdery substances on concrete walls is not likely to be mould itself, but it's indicative of moisture passing through the walls and creating a humid environment. If there are mouldy, musty odors, then mould will be somewhere.

Types Of mould In Crawl Spaces

Dry rot damage on wood in North Sannich

Dry rot damage on wood. Notice the cube-shaped pieces flaking off the wood's surface.

mould and rot fungi can be classified in two ways: what grows on the surface, and what grows within the wood itself.

Surface mould fungi will cause cosmetic discoloration only, and it will not significantly damage the structural strength of the wood. This mould can simply be cleaned off the surface.

Decay fungi will darken and shrink the wood, leading to severe structural damage of the wood and the eventual crumbling and decomposition of the wood overall. Wood with decay fungi looks soggy and spongy. This cannot simply be cleaned off, and replacement of damaged wood may be necessary.

One other variety of wood-damaging fungi is dry rot, also known as brown rot and cubical rot. As displayed in the photo above, wood damage from this kind of rot is shown as deteriorating the wood into small squares or rectangles. Often mistaken for termite damage because of its appearance, this is an extremely damaging type of fungi.

One other unique feature of dry rot is its ability to pull water from far-away water sources through "rhizomorphs." Rhizomorphs can extend for as much as thirty feet, stretching across brick, concrete, mortar, and similar materials. In the case of Serpula lacrymans, water has been transported as much as three stories upwards!

More About Dry Rot Damage

Preventing & Eliminating Crawl Space mould

Humidity Warning!

Some major cases of crawl space humidity stem from where your dryer vents end. If your dryer is sending air into your crawl space, it's also sending a ton of humidity with it! This humidity is exactly what mould, rot, and mildew need to start thriving in your home. If your dryer is sending air into your crawl space, fix the problem right away!

Traditional methods of mould removal, such as bleach and water, will not provide a long-term solution for mould removal. These methods do not address rot damage or humidity issues.

mould will begin growing again in 24-48 hours if the mould-growing environment is not changed. And dormant fungi can reactivate when dry, infected wood becomes wet again.

The solution to crawl space mould and moisture is to seal the crawl space vents, install a plastic liner on the walls and floors, and dry the space with a self-draining dehumidifier. Otherwise, any repairs and mould remediation steps you take are a temporary fix only.

Island Basement Systems offers free crawl space repair quotes in British Columbia, including Duncan, Campbell River, Langford, Courtenay, Port Alberni, Squamish, Esquimalt and many areas nearby. Contact us today to get started!


Looking for a price? Get a no cost, no obligation free estimate.

our service area

We serve the following areas

Our Locations:

Island Basement Systems
467 John St
Victoria, BC V8T5H1
Our service area