Which criteria to consider when choosing exterior insulation

Whether you are planning a brand-new building or renovating an existing one, exterior wall insulation is something you should consider carefully. Effective exterior insulation has many benefits, including better energy efficiency and more comfortable living conditions for the building’s residents.

With the wide variety of exterior insulation available on the market, it can be difficult to determine which is the best choice for your building.

To help you make an informed decision, our Adfast specialists have prepared a list of the most important criteria to consider when choosing exterior insulation.

Why insulate exterior walls?

Before we get into the criteria for good exterior insulation, it’s worth taking a look at why insulating your exterior walls is important in the first place. Read on to find out why insulation materials are a good investment.

Lower energy consumption

Good exterior wall insulation, particularly around the doors and windows, helps keep your home warm in winter and cool in summer, reducing the energy needed to heat and cool the building. It also means less strain on your heating and air conditioning. All of this saves you money.

Noise reduction

Insulation materials absorb sound waves and vibrations, reducing the unwanted noise that travels through walls and floors.

Better humidity control

Daily activities like cooking, cleaning and showering produce water vapour that increases the humidity in your home. The moisture can get trapped in the walls, leading to mould growth that can damage the building and create health hazards. Insulation acts as a protective barrier between moisture and the building structure.

Infestation prevention

Some types of insulation such as polyurethane foam (see below) can protect buildings from pest infestations. Insulating foam seals off the gaps insects and rodents use to get inside.

Types of insulation for exterior walls

Before we get to the selection criteria, let’s take a look at the types of insulation that are available at the hardware store.

Insulation batts and rolls

Insulation batts and rolls are flexible products made from mineral fibres such as fiberglass and mineral wool. They are available in sizes designed to fit in standard wall stud, attic and floor joist spaces.

Blown-in or loose-fill insulation

Blown-in or loose-fill insulation is generally made of small particles of fiberglass, mineral wool or cellulose. The particles are blown into spaces using special pneumatic equipment (hence the name). This type of insulation is useful for cavities that are irregular in shape or contain wires, ducts and pipes.

Foam board insulation

Foam boards are rigid panels of insulation that are very effective for exterior walls.

Spray foam insulation

Spray foam insulation such as polyurethane foam can be sprayed into walls, on attic surfaces and under floors to provide insulation and reduce air leaks. When it comes into contact with the air, it expands, filling gaps that might otherwise be thermal bridges.

This is the best type of insulation for sealing window and door frames and openings for electrical wires and plumbing pipes.

The criteria to consider when choosing exterior insulation

Insulation can be made from a variety of different materials and is available in a range of shapes, sizes and formats. Each type of insulation has characteristics that make it suitable for different types of construction and renovation projects.

Here are the criteria to consider when evaluating and comparing insulation products:


The R-value (or thermal resistance value) measures an insulation material’s ability to resist heat flow into or out of a building. The higher the R-value is, the more effective the insulation will be. Keep in mind that a material’s R-value will be lower if it is compressed.

The R-value recommended for optimal insulation depends on factors like the local climate, building standards and the surface you want to insulate (floor, ceiling, wall, etc.).


With most construction projects, the goal is to get the best result possible within budget. The same goes for insulation.

Some types of insulation are more effective than others, but the price per square metre is usually proportional to their performance. That means that if you have a large area to cover, you may want to choose a less expensive option to keep costs down.

That being said, it’s not a good idea to just go for the cheapest option without considering other factors, because higher-quality insulation will be worth the investment in the long term.


Insulation is not something that needs to be replaced often. Most insulation material is designed to last around 20 years. However, it should be noted that some types of insulation can be affected by particular phenomena.

For example, mineral wool insulation has a tendency to compress over time. Thermal resistance is directly related to the thickness of the insulation, so the more compressed it gets, the less effective it will be.

Conversely, other materials like polyurethane insulating foam have mechanical properties that make them more resistant over time.

The space that needs insulation (type of wall, material, etc.)

The space or area you want to insulate should also factor into your choice of insulation.

If the space is large, you can choose almost any option. However, if space is limited, it’s best to opt for a product with a good R-value, but less volume.

In some cases, insulating a small area may require precision, such as when installing a door. For this type of situation, many window and door installers recommend applying polyurethane foam with a foam gun.

How easy it is to install

Sometimes, choosing the right type of insulation can make an insulation project much easier and less time-consuming.

Imagine that you want to insulate a room without opening up the walls. In this type of situation, a practical choice might be polyurethane insulating foam, which would enable you to insulate the wall through a few small holes.

On the other hand, if the walls aren’t finished yet, it’s very easy to place foam boards or mineral wool insulation batts between the studs.

The Adfast Adfoam product line: the best polyurethane insulating foam

In conclusion, there are many criteria to consider when looking for exterior insulation. But if you are familiar with the insulation materials available and take the time to evaluate them based on the factors listed above, you will have everything you need to make the right choice.

If you decide that polyurethane insulating foam is the right choice for you, you can rest assured that the Adfoam product line is designed to meet all of your needs. You can even contact our Adfast experts for help choosing the right foam for your project.