How to Prevent Condensation on Interior Walls?

How to Prevent Condensation on Interior Walls

How to Prevent Condensation on Interior Walls


Condensation is explained as water collected as droplets on cold surfaces when humid air is in contact. It is usually caused by a lack of ventilation indoors. The third form of water – vapor – causes the most invasive damages to your living, working, or storage space. 

This is because water might collect around your home due to clogged or grading eaves and downspouts, or saturated earth around your building can without question lead to rotting wood or a damp basement. As it wasn’t enough, even daily activities like cooking, cleaning, and showering and even plants can add moisture to a house. Other sources of moisture in a home include snowmelt, humidity, and fog, rain, humidifiers.

And this way moisture becomes the homeowner’s worst nightmare. As condensation paves the way to excess moisture, the latter becomes dangerous if the problem is not solved. Moisture indoors can expose residents to respiratory disorders and it is the number one source of mold growth and building structure damage. So how to prevent condensation on interior walls? Read on…

How insulation prevents condensation?

Condensation becomes a problem when interior walls lack insulation. See, an insulation system would not be considered complete without preventive measures against moisture accumulation. And as stated on the Ontario Building Code, quote: Each section of a building that separates the inside from the outside and vice versa must have:

  • A thermal barrier
  • A vapour retarder
  • An air barrier

While a thermal barrier and an air barrier work towards a more energy-efficient home that has little to no drafts, the vapour retarder (vapor barrier) is needed to control moisture indoors. It prevents water vapor from moving into building assemblies (walls, crawl spaces, and attic) where it can condense into liquid water within the structure

How insulation prevents condensation
Condensation in cold and warm humid climates

How does a vapor barrier work in cold climate areas?

Vapor retarders, vapor barriers, or vapor diffusion retarders, are usually found as polyethylene plastic that is applied to the inside face (the warm face) of stud frame walls. They have been used for years to minimize condensation inside the walls. To understand the importance of a vapor barrier, simply imagine (images below) a cross-section of a wall in winter (inside-insulation-outside). The outside area is normally cold and the inside area is a heated space (warm).

Now, if a vapor barrier is not set in the wall, droplets of condensation are going to be formed in the wall cavities. This would then lead to moisture accumulation and poor indoor air quality. But this is why a vapor barrier is applied to the warm inside part of the wall. When in place, warm air can not make its way into the wall cavities. The latter remains dry and keeps moisture far from your walls.

Spray foam insulation 3in1 – vapor, air, and thermal barrier

As mentioned above, a building structure needs air and a thermal barrier in addition to the vapor barrier we already discussed. When it comes to air and thermal barriers, there are several insulation materials that manage to create an airtight seal that eventually reduces energy bills by keeping heat inside and vice versa in the summer months. But as good as it may seem, some materials cannot be used for every application. Through air movement or leaks, moisture can get trapped inside the material of fiberglass insulation and lead to the growth of mold and mildew. When it happens, it can significantly lower the insulation capabilities and also cause serious damages to the building structure. 

This is why we recommend using spray foam for your complete building envelope. A spray foam insulation system acts as a thermal, air, and vapor barrier, and additional polyethylene sheeting is not necessary. Spray polyurethane foam does not absorb moisture and at the same time, it prevents leakage by sealing air gaps. 

No fiberglass or mineral wool this time

Here at Eco Spray  Insulation, we highly recommend using spray foam for your home’s insulation needs and even more when it comes to preventing condensation on interior walls. See, other insulation methods like fiberglass and mineral wool are air-permeable materials that can sometimes allow moisture to condense and collect, which will lead to what you want the least – mold growing within your house walls. If you have an older home and are spotting drafts, unusual smells, or hot or cold spots, it can be because your interior walls contain this type of insulation material. Whether your home is new or old, it’s worth examining to find out how it is insulated, and what we can do to improve or replace the insulation if necessary.

Another reason to add insulation to your attic and basement walls 

A Canadian winter calls for a well-insulated house. By insulating your attic and basement you are lowering your monthly energy bills and increasing your liveable space while protecting your family members from moisture accumulation. But as with interior walls, when a basement or attic is not properly insulated, warm air can come into contact with home walls which are naturally cooler due to the low temperatures on the other side. The warm air will condensate and this will give mold a good head start. Adding insulation to your attic and basement, you can prevent this issue and keep your house safe and healthy. 

Why Choose Eco Spray?

Eco Spray Insulation Company is proud to be serving the Greater Toronto Area and the suburban communities with insulation services of the highest quality. With the passing of years, we have established ourselves as experts in commercial and residential insulation. Our services include, but are not limited to, attic insulation, basement insulation, insulation removal, and air barrier systems.

According to our client’s requests, and depending on the project, we use conventional insulation methods (cellulose and fiberglass) and our winning product – spray foam. Simply let us know when you are ready to get started and our team of professionals can help you access the most inaccessible parts of your house, get rid of mold for good, and enjoy the benefits of insulation for decades to come. Contact us to get a free estimate today.

Building Science

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