What is a Vapour Barrier?

It’s hard to deny that basements and bathrooms are generally the dampest rooms in a home. Keeping up with maintaining these spaces can often be a challenge. It’s crucial to keep humidity and moisture levels as low as possible, as excess moisture will lead to deterioration as well as mould and mildew growth. So what methods can you put in place to keep these things at bay? Enter the vapour barrier.

The vapour barrier comes down to having a good level of insulation in the walls and floors, helping you to keep the amount of humidity in these areas under control. This installation can be an excellent way to solve persistent humidity problems.

What is the role of a vapour barrier in a home?

When building a new home, there are two vital questions that all professionals take into consideration:

• How can we keep water out?

• If water gets in, how can it escape?

These questions can help us think more broadly about why we might install a vapour barrier in the first place.

The Canadian Mortgage and Housing Corporation (CMHC) has compared the different insulation components of a house to a wool sweater: “A wool sweater will keep you warm if the wind is not blowing and it is not raining. On a windy, rainy day, wearing a nylon shell over your wool sweater helps keep you reasonably dry and warm.”

This metaphor is nice for a house, as its layers operate in a similar fashion. On the outside, underneath the brick or siding, there’s an air barrier that works in the same way as the nylon aforementioned— it keeps the wind from blowing through and finding its way into your home. Then there is the insulation, like the sweater and finally a vapour barrier. This protective layer helps keep moisture away from the house's structure, where it can do damage.

A vapour barrier is generally made of plastic or foil used as a damp-proof layer to curve the formation of moisture in walls, floors, crawl spaces, attics, your foundation as well as your roof. Not only will this help the structure of your home last significantly longer, but it will also aid in the avoidance of mould and mildew growth which are typical of excess dampness. Having mould and mildew anywhere in the surfaces of your home is a serious health risk. Further, damage caused by excess condensation or humidity is challenging to deal with. It can greatly threaten the materials themselves as well as any insulation already in place.

Not only can moisture find its way into your home from the exterior, but there are many sources within your interior. Many daily activities involve a buildup of moisture and this includes cooking, doing dishes and laundry, taking a shower and so on. This humidity and condensation can compromise the integrity of your walls, ceilings and floors but a vapour barrier can assist you in keeping everything under control.

Installing a vapour barrier: things to know

There are several materials that can be used as a vapour barrier aside from the ones mentioned above, and they are as follows:

• Elastomeric coating;

• Metalized film;

• Vapour retarder paints;

• Asphalt-coated paper;

• Exterior grade plywood;

• Glass and metal sheets.

All the aforementioned materials have a different level of permeability, and the one you choose will greatly depend on the climate you live in as well as how much humidity you produce inside the home. Do spend some time researching the proper vapour barrier right for your conditions, as it would be frustrating to put in time, energy and money to an install that isn’t resistant enough. It’s also worth mentioning that for a vapour barrier to work correctly, there needs to be sufficient insulation in the walls of your home. Insulation is very important, and if you’re curious about this subject, check out our article on the top signs of poor insulation. 

As mentioned, the vapour barrier will be placed throughout walls, ceilings and floors. In your walls, it should be installed before posing the gypsum board and on the interior face of the insulating material. Basically, placed between the insulating material and the drywall.

With this type of installation, the humidity will not move through the walls, therefore maintaining the longevity of the surfaces. Installing a barrier in both floor and walls will further improve the room's resistance to humidity.

Benefits of a house that is well insulated

Investing in your home's insulation can really improve your quality of life. Not only will it prevent mould and mildew growth as well as excessive humidity, but it will also allow a better airflow. Depending on the insulating material you’ve used, you may end up saving up to 50% on your electricity bills. This means that a well-insulated house will ensure a comfortable indoor temperature all year round, both summer and winter.

Lastly, keeping energy use and costs down is a green-friendly practice, and we should all be thinking a little be more about taking care of the environment.