Understanding Crawl Space Humidity

a flooded basement floor in a Strathroy home

When moist air enters a vented crawl space, condensation occurs on cool crawl space surfaces.

Crawl space humidity has been plaguing homes in Ontario since the first day they were built.

As the humidity levels rise in crawl spaces, moisture condensates on the surfaces, leading to serious problems in your home. These problems can lead to health issues and the need for expensive repairs.

Most of the problems traditionally associated with damaged, rotting crawl spaces are due to basic flaws in the ways that crawl spaces were designed.

We offer free crawl space repair quotes in London, Sarnia, Windsor, Stratford, St Thomas, Chatham-Kent, Essex, Amherstburg, Strathroy, Leamington, Exeter, St Marys, Mount Forest, Dorchester, Forest and many areas nearby. To schedule your free appointment, call or e-mail us today!

illustration of air movement from a crawl space into the home

How Crawl Space Humidity Begins

When the frame of your home was first built, it was a large wooden box, with few, if any, holes in it.

Then came the other contractors. As plumbers, electricians, HVAC workers, and countless other professionals began to work in your home, they began to cut channels in your walls and floors. Pipes, wires, cables, ducts, and other things were passed through, and your home's construction was completed.

Then, over time, your home began to expand and contract. The once-tight seams began to warp slightly, and more crevices and openings appeared. There are a lot of openings that can develop between your first floor and your crawl space!

In your home, warm air rises, leaving through your attic and upper floors. As this happens, a vacuum is created on the lower floors. Air from the outside -- and from your crawl space -- is pulled upwards to fill the space.

If you have crawl space vents, they will also become part of the air movement in your home. As air is pulled out of the crawl space and up into the home, new air will be pulled in through these vents.

Here's the key point: If the air outside is wet or humid, then your crawl space vents are bringing in moisture.

Mold and rot in a Windsor crawl space

Wood that stays damp in a dark crawl space is an ideal Mold habitat. Eventually, Mold causes wood decay that can destroy structural parts of the house.

What Humidity Does To A Crawl Space

Crawl space humidity leads to all of the following problems in your home:

  • Rotting & Mold
  • Rusted, Corroded Metal
  • Odors & Allergens
  • Higher Utility Bills

As humidity builds in your crawl space, it creates an ideal space for Mold and rot to grow.

As it does, all organic material in your crawl space will be damaged -- including wooden floorboards and structural support beams.

A rotting crawl space will begin to sag, creating uneven floors above. In some extreme cases, sections of the floor may even begin to cave in!

additionally, many pests (termites, carpenter ants, wood-eating beetles, crickets, et al.) love rotting, Moldy wood. Your open vents will be an invitation for them to move in.

As the Mold and rot increase, and animals begin to live (and die) in your crawl space, odors will begin to rise into your home along with the crawl space air. Mold spores are a known allergen, and they can significantly affect anyone in the home who suffers from asthma or allergies.

During the hot summer months, crawl space humidity will also increase your home's cooling bills. Have you ever seen water dripping from a window-mounted air conditioner? This is because a large part of the job of an air conditioner is to dehumidify the air it cools. Humid air is much more expensive to cool than dry air! And of course, that freezing cold winter air that enters through the crawl space vents isn't helping either....

Mold needs three important things to survive:

  1. Warmth
  2. Moisture
  3. Food

Of these, the easiest to control in your home is moisture.

Controlling Crawl Space Humidity

Fortunately, controlling crawl space humidity is easy! At Advanced Basement Systems, a crew of our crawl space contractors can usually install a moisture control system in less than a day.

We recommend starting by sealing those crawl space vents, then following up by installing a crawl space vapor barrier on the walls and floors. A dehumidifier is a great finishing touch, drying out the space and helping you to best preserve your home.

At Advanced Basement Systems, crawl space repair is our specialty, and we'd like to show you why we're the best. To help you decide which repairs are best for you, we offer free crawl space repair quotes to homeowners in our area.

We serve Ontario, including Windsor, London, Sarnia, St Thomas, Chatham-Kent, Leamington, Stratford, Amherstburg, Strathroy, Essex, Wallaceburg, Hanover, Kincardine, Point Edward, Tecumseh and many areas nearby. To schedule your free quote, contact us today!

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

our service area

We serve the following areas

  • Aylmer
  • Beachville
  • Bright
  • Brownsville
  • Burford
  • Burgessville
  • Cathcart
  • Clear Creek
  • Courtland
  • Delhi
  • Eden
  • Embro
  • Erieau
  • Hickson
  • Ingersoll
  • Innerkip
  • La Salette
  • Lakeside
  • Langton
  • Morpeth
  • Mount Elgin
  • Mount Pleasant
  • Muncey
  • Norwich
  • Oakland
  • Otterville
  • Plattsville
  • Port Burwell
  • Port Rowan
  • Port Stanley
  • Princeton
  • Scotland
  • Sparta
  • Springford
  • St George
  • St Thomas
  • St Williams
  • Straffordville
  • Teeterville
  • Tillsonburg
  • Turkey Point
  • Union
  • Vanessa
  • Vienna
  • Vittoria
  • Wallacetown
  • Walsingham
  • Waterford
  • Wilsonville
  • Windham Centre
Our Locations:

Advanced Basement Systems
23576 Prince Albert Road
Chatham, ON N7M 5J7
1-226-706-2439


Advanced Basement Systems
199 Exeter Rd Unit E
London, ON N6L 1A4
1-226-271-8708
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