Despite what the market says is the most popular insulation material or method at any given moment, the truth is each project has its own set of circumstances that call for a recommended set of options. And within those options, the specifications and installation can have a massive impact on the result.
It’s important to understand insulation materials and how they work within your home’s construction and the environment in which you live. The product that is quickly becoming one of the most popular options in North America is spray polyurethane foam (SPF).
Spray polyurethane foam is a heat-activated polymer that is a foam insulation that is sprayed into place. It is made by mixing two ingredients onsite using special equipment. The mixture is sprayed through a heated hose onto the surface that needs to be insulated. As the chemical reaction between the two ingredients takes place and the substance heats up in the hose, the liquid turns foamy, expands and eventually hardens in place.
Open-cell SPF is lighter, less dense and cheaper but has less insulating power (or a lower R-value). Closed-cell SPF is denser and more expensive, can provide a bit more rigid support to certain structures and can act as a water vapor barrier, because it is less permeable.
Why is SPF so popular? Spray foam has the potential to tackle air leakages better than many other insulation options. Because it is sprayed into place, the foam can fill the envelope. It can be applied to vertical or horizontal surfaces to act not only as thermal insulation, but also as an air barrier. It’s synthetic and does not attract rodents or insects. When applied properly, spray foam can contribute to a successful energy-efficiency strategy.
The relative ease of installation makes it a popular choice for contractors. Even though it can be expensive, its relatively high R-value per centimetre makes it a competitive option. It’s particularly helpful for renovation projects where traditional batt or board insulation may be difficult to insert. With spray foam it’s possible to inject the insulation into a wall cavity, for example, or apply it to a sloped surface.
As with many building solutions, the increasing popularity of a product or method means an increase in misuse and misunderstandings. It is common to find examples of spray-foam insulation that have been installed incorrectly.
The most common problems with spray-foam applications are:
- The chemicals were not mixed correctly, and the foam starts to pull away from the neighbouring surfaces
- The installers rush through the installation, leaving gaps and holes that reduce the efficiency of the product
- A sufficient thickness either was not specified or was not executed as specified during installation
- The local climate was not taken into consideration, and the temperatures or humidity levels were outside of the manufacturer’s specifications
- In cold climates, a vapour barrier was not installed over the spray foam, sometimes causing roof rot.
Installation is a key factor with any kind of insulation and can be the difference between insulation that works or causes problems.
It is essential that anyone working on the construction or renovation of a home using SPF follow the recommended health guidelines. Please don’t think that you can install this in your shorts and T-shirt on the weekend. Consult a professional and do your research.
The good news is learning the pitfalls is just part of being more aware of the consequences of a certain decision. Every insulation material has advantages and disadvantages. SPF is a viable solution for certain homes and can offer substantial energy savings if installed correctly. You just need to be aware that, relative to other materials, the installation can be easier to execute but also easier to rush through. Knowing what questions to ask your installer can go a long way toward obtaining optimal results.
Sue Wastell is the President of the London Home Builders’ Association and Owner of Wastell Homes in London.