Monday Sep 28th, 2020


Why You Shouldn’t DIY Insulation

There are many benefits to good home insulation. It will lower your heating and air conditioning costs, minimize temperature fluctuations, prevent mould growth, buffer outside noise and reduce your home’s environmental impact. Although you may be tempted to DIY, hiring an insulation professional will pay off in how they assess your home upfront and then install the best solution.

Signs that you may have insulation problems will vary by season. In winter, look for walls and floors that are cold to the touch, high heating costs, uneven temperatures throughout the home, melting snow on the roof, or mould growing on walls. In summer, insulation is an issue if you have high cooling costs, uncomfortably hot rooms, an ineffective air conditioning system, or mould growing in the basement.

The Canada Housing and Mortgage Corporation (CMHC) compares a properly insulated house to how we dress for inclement weather. According to the CMHC, “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. A house is similar. On the outside, underneath the brick or siding, there is an air barrier that does the same thing as the nylon – it keeps the wind from blowing through. Then there is the insulation (like your sweater) and a vapour barrier, which helps keep moisture away from the house structure where it can do damage.”

Insulation Effectiveness

The effectiveness of insulating materials is measured by R values – the higher the R value, the more resistance the material has to the movement of heat. Insulation products sold in Canada are labelled with both R (imperial) and RSI (metric) values. Provincial building codes specify minimum R and RSI values for each area of a newly-built house, so it’s important to know your local building code requirements if building a new home.

The R value of any insulation material will be reduced if it is not installed by a professional, who will take care to avoid compressing the insulation, leaving air spaces around the insulation or allowing air movement in the insulation. So don’t DIY – hire a professional to do the installation.

Types of Insulation Materials

The Canada Housing and Mortgage Corporation (CMHC) provides a very detailed Table of Insulation Materials, along with the R values and Pros/Cons of each type. Here is a summary of the four major types of insulation materials:

Batts. Usually pink fibreglass or darker mineral wool that is pre-cut into sheets or rolls designed to fit snugly between wall studs.
Rigid foam board stock. Primarily used on the home’s shell (under the siding or brick) or to line exterior basement walls or to insulate below the basement slab.
Loose fill. A very light fibrous fill, made of either fibreglass (pink or yellow) or mineral fibre (usually brown.) These insulations typically require a professional installer.
Spray-Applied. These insulations fill cavities very well but must be applied by a specialized contractor. There are two types of spray foam: low-density open-cell polyurethane and higher density closed-cell polyurethane. Closed-cell is the more popular choice for attics and exterior walls as it helps to create a more airtight home is resistant to mould, and has the highest R-value available.


A home that is well insulated is well sealed, but properly ventilated. Healthy homes need to breathe and by adding more insulation, especially spray foam, you may also need to add extra venting or an air exchanger. For example, a Heat Recovery Ventilator (HRV) exchanges indoor air with fresh outdoor air that is pre-heated by the warm indoor air that’s going outside.

Good ventilation will bring in the fresh air and get rid of stale, indoor air. If not, condensation will occur and that moisture can lead to mould, which can cause health issues such as irritation of eyes, nose and throat, coughing/wheezing, shortness of breath and allergic reactions.

Research Before You Hire

Before hiring an installer, read their online reviews, ask to contact a few of their recent clients, and ask what materials they plan to use and why. Ask if they have insurance and request a copy of their insurance certificate as proof. When hiring a spray foam installer, ensure they are licensed by either the manufacturer (for example, BASF Foam Master Certification) or an industry association, such as the Canadian Urethane Foam Contractors Association Inc. (CUFCA).

Before the Work Begins: Assess

The best companies use sophisticated assessment techniques before the work begins.Techniques used to find air leakage pathways include ‘Blower Door’ testing, thermal imaging as well as smoke pencils or fog machines to trace air leakage.  A blower door is a machine with a large fan that measures how airtight your home is. It can also be used the airtightness of ductwork and to help locate air leakage sites.

Potential Air Leakage Pathways

Once these air leakage pathways are found and repaired, good contractors will often vacuum the old insulation material out, apply two inches of spray foam (which addresses the air leakage issues in the attic floor) then blow-in loose fill insulation on top for optimal insulation. By using these assessment techniques, the potential value of energy savings can be accurately quantified by measuring before and after the insulation work is done.


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