The Crawl Space Encapsulation Checklist
A Winnipeg Homeowner’s Guide
Signs Your Crawl Space May Need Attention
Crawl spaces affect the temperature, moisture, and air that move into the rooms above them. When a crawl space isn’t sealed or insulated properly, you’ll usually notice one or more of the following:
Cold floors in winter — heat is being lost through the floor assembly.
Musty smells — moisture is accumulating under the home.
Visible mold on joists — you may notice subtle spots forming on the wood.
Insects or rodents — damp, unsealed crawl spaces are comfortable hiding spots.
Sagging or fallen insulation — materials are absorbing moisture and losing effectiveness.
Condensation on ductwork or pipes — warm interior air is meeting cold crawl space surfaces.
These signs indicate that moisture and outside air are moving into the crawl space instead of being controlled. This is a common issue in older Winnipeg homes and homes without proper vapor barriers.
Step 1: Addressing Drainage Sources
Before anything gets sealed or insulated, the crawl space has to be dry. The most common ways water gets in are:
Poor grading around the foundation
Downspouts draining too close to the house
Groundwater seeping through the soil
Sometimes the fix is as simple as extending downspouts a few extra feet. In other cases, a perimeter drain or sump pump may be necessary. The goal at this stage is straightforward: stop liquid water from entering the crawl space so that whatever materials are installed afterward have a dry, stable environment to perform in.
Step 2: Installing a Proper Ground Vapor Barrier
Once liquid water is under control, the soil itself becomes the main source of moisture in a crawl space. To stop that moisture from rising into the home, the ground is covered with a continuous vapor barrier, usually a 10–20 mil polyethylene or reinforced liner.
When the ground is fully sealed, moisture in the air drops and the crawl space becomes far more stable. Adding a good vapor barrier is what prevents that damp air from moving into the rooms above — and it sets the foundation for insulation to actually work as intended.
Step 3: Insulating your crawl space RIGHT
In a cold climate like Manitoba, the most effective approach is to insulate the crawl space walls, not the underside of the floor. Insulating the concrete or block walls helps bring the crawl space into the home’s conditioned envelope.
Closed-cell spray foam is commonly used here because it adheres directly to masonry, resists moisture, and provides both insulation and an air seal at the same time. This method keeps the entire area more consistent in temperature and helps the floors above stay noticeably warmer.
Step 4: Deciding Between Vented and Sealed Crawl Spaces
In the past, many crawl spaces were built with open vents to “let them breathe.” However, in cold climates, these vents often pull in cold, damp air, which can make floors colder and increase moisture problems. A sealed crawl space closes those vents and controls the environment instead.
Here’s the difference in simple terms:
Vented Crawl Space
Outdoor air enters freely. In winter, this makes the space cold, increases heat loss, and can lead to condensation under the floor.Sealed Crawl Space
Vents are closed, the ground is covered, walls are insulated, and air movement is controlled. The temperature stays more stable, and moisture is easier to manage.
For most Winnipeg homes, a sealed crawl space is simply the better choice.
Step 5: Humidity Control in your crawl space
Even after the crawl space is sealed and insulated, humidity still needs to be managed somehow. Moisture in the air can come from seasonal changes, indoor air movement, or small remaining leaks. Keeping humidity in the right range helps prevent mold from damaging your wood framing.
A few simple guidelines:
Aim for 50–60% relative humidity in the crawl space.
If humidity rises above that level, a crawl space dehumidifier can help maintain balance.
Make sure air can circulate — blocked vents or tight corners can trap humidity.
Check the space a few times a year, especially during spring melt and humid summer days.
For help with any of these assesments it is recommended that you seek a professional checkup. We are happy to give reports for all of these issues and more!
Final Thoughts: Creating the perfect Crawl Space
A crawl space doesn’t stay dry and stable on its own. It takes the right steps in the right order—controlling moisture, sealing off air leaks, and insulating where it actually makes a difference.
Every crawl space is a little different, and the best solution depends on how your home is built and where the issues are starting. If you’re noticing cold floors, damp air, or musty smells, our professionals at Canadawarm can take a look and help you decide what needs to happen next.