Exterior Wall Insulation: Top 5 Problems to Look Out For

Exterior Wall Insulation: Top 5 Problems to Look Out For

Exterior Wall Insulation: Top 5 Problems to Look Out For


During the winter months, exterior walls might need thick and perfectly fit insulation. Do your exterior walls feel cold when you touch them? It might be due to certain areas of the wall cavities lacking insulation or insulation has not been properly installed. 

Cellulose and fiberglass insulation can also compress or settle down with the passing of time. This will result in the loss of heat insulation qualities.

Exterior wall insulation problems directly affect the comfort of your home. They make it harder to control the indoor climate, causing the HVAC system to work extensively and resulting in higher energy costs.

Another problem compromising the exterior wall insulation efficiency is the quality of doors and windows installation. When areas around windows and doors are not properly sealed, they leave room for air and vapour leakage.

To mitigate the exterior wall insulation problems, make sure that all the wall cavities have been properly insulated. An air barrier would do pretty good work in limiting or blocking the flow of indoor warm air inside the walls. This will prevent the condensation of the indoor warm air in contact with the outside cold walls. It will also minimize the conditions for mould growth.

Exterior wall Insulation using spray foam insulation form Soprema
Exterior Wall Insulation: Top 5 Problems to Look Out For 3

Some of the main problems related to exterior wall insulation include: 

  • moisture in exterior walls, 
  • settling of insulation over time,
  • condensation on exterior walls, 
  • ventilation issues, 
  • cracks and mechanical damages.

Moisture in Exterior Walls

Exterior walls cannot function properly if moisture finds its way and infiltrates the wall system. Moist walls create an ideal environment for mould growth. We find moisture in two different forms: water and vapour.

There are several paths through which water can infiltrate exterior walls systems. Water that comes from rain can find its way through cracks or other defects in the roof and around doors and windows.

Groundwater that is found around the house can penetrate the wall structure through capillary suction. During this process, water is suctioned through the wall capillaries from below and transferred into higher parts of the wall.

And there is water in the form of vapour, which doesn’t need any cracks or breaks to penetrate the wall. Water vapour diffuses through the wall materials and gets condensed in contact with cold wall surfaces.

If moisture finds its way inside your walls, then conditions are met for the mould and mildew to flourish. Certain insulation materials like fiberglass and cellulose insulation are known to retain moisture and thus, serving as mould growth promoters.

The best solution, in this case, would be to make sure that the wall cavities are properly filled with insulation. The best type of insulation to isolate your exterior walls is spray foam insulation. SF insulation is dense, has a high thermal resistance value, and does not retain moisture.

Old Insulation in Exterior Walls

There are two types of loose fill insulation materials: blown in cellulose and fiberglass insulation. These insulating materials tend to settle and sag over time. 

If insulation sags, then it loses its thermal insulating properties. Thus, it is not able to preserve the energy of the building. Outside cold air will penetrate the exterior walls while warm indoor air will leak outside. This will cause the HVAC system to work intensively, making it harder to control and maintain the required indoor climate.

If your exterior wall insulation has lost its thermal insulating qualities then it might be time for a replacement. You can either replace it with the same material or opt for a better option such as injected spray foam insulation. The latter does not settle nor sag. It does not retain moisture and is dense enough to retain its shape and thermal insulating properties.

Fiberglass and cellulose blown in insulation on the other hand are not a good option for the exterior walls. They come in the form of loose fill insulation which has the tendency to settle over time. These insulating materials have a low thermal resistance value per inch. Thus, exterior wall insulation with loose fill insulation would not achieve the required R-Value.  

Condensation on Exterior Walls

In places with cold weather such as Ontario and the greater area, condensation on exterior walls is a known problem. This is the result of indoor warm air coming into contact with the cold surfaces of the exterior walls.

Condensation on exterior walls is prevented by using air barriers to stop the flow of indoor warm air. Vapour barriers on the other hand are used to limit the vapour diffusion.

But condensation does not happen from the inside only. There is also condensation that comes from the frost generated on the outside of the walls during the colder months. Frost generated on the outside will thaw comes the warm weather. The liquid water can thus find its way inside of the exterior walls.

If cavities on the exterior walls are not properly insulated then the condensed moisture can cause the walls to rot or to generate mould and mildew.

Exterior Walls Ventilation Issues

Ventilation ducts are installed for certain reasons. Instead of covering them up, they need to be extended further in order to properly exercise their function.

Ventilation ducts serve as air passage channels to control the indoor climate and air quality. That being said, you must be careful to not cover them up as it might cause condensation.

If inside dry air is an issue, then you should turn to innovative ventilation equipment. They will prevent air from drying out and at the same time allow air circulation.

It is very important to understand how the exterior wall insulation will affect the ventilation of the indoor environment. It will be easier for you to control the air circulation and maintain the required indoor climate.

Installed ventilation boxes need to be checked for installation quality and functionality. If you do not have any ventilation equipment in place, then you should contact an insulation expert. They will assess the areas which need ventilation and will install them properly.

Cracks and Damages on Exterior Walls

These types of damages do not appear themselves on the exterior walls. It is however possible for them to occur due to external factors. It can be from extreme weather conditions, hard objects hitting the exterior walls, or even vehicles being clashed on your walls.

Though appearing rarely, these types of problems occur and we are here to address them. In case of exterior wall cracks and damages be quick to contact an emergency response contractor. They can have a detailed look and offer the correct solution to repair your walls.

A quick response is crucial to preventing further damage to the exterior wall structure. An open wall is more prone to moisture penetration and mould growth as a consequence.

Other areas that require special attention are the openings and air leakages around the windows and doors. The silicone used to seal them loses its function over time. Functionless silicone will not be able to block outside air and moisture infiltration. It is best to minimize silicone usage and replace this with adequate beads and trims.

Exterior Wall Insulation Problems Solved

To overcome exterior wall insulation problems it is important to first understand how each insulation material works and what their insulating properties are.

Loose fill insulation such as blown in cellulose and fiberglass have a lower thermal resistance value per inch. Thus, more material is needed to achieve the required R-Value. They also tend to settle and sag over time. This will result in loss of the thermal insulating qualities.

Spray foam insulation on the other hand is a dense material with a higher thermal insulating value per inch. It does not retain moisture and also maintains its shape and form over time. These qualities make spray foam the best insulation material for your exterior walls.

Do your exterior walls feel cold to the touch? Do you need new insulation or replace the old insulation on your exterior walls? Do the exterior walls show any sign of moisture accumulation or mould growth? Call us at (416) 860-6664 or send us an email at [email protected] for a free estimate.

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