Prescription for energy efficient homes: Spray foam insulated attics

Installing insulation in an often-overlooked space – the attic – is one of the most effective ways to achieve an energy-efficient home. More specifically, make sure it’s medium-density closed-cell spray polyurethane foam insulation (ccSPF), because, as we’ll explain, it’s truly an efficiency powerhouse.


By Doug Brady

With low housing inventory and fatigue with the current pandemic restrictions, Canadians everywhere are investing in renovation. In the second quarter of 2021 when compared to the first quarter, there was a 30% increase in home renovation loan applications, as per Simply Group. From the summer months of May through August, June saw the most loan applications, followed by August and May, reflecting the surge in home improvement projects during summer. On a provincial level, Simply Group reported that Quebec saw a 96% increase in home renovation loan applications in Q2, compared to Q1 2021, adds Simply Group.

There’s a combination of homebuyers looking to make upgrades to their homes and sellers are renovating to increase their selling price. Changing the aesthetics of a home is the popular “freshen-up” solution. However, investing in energy-efficiency upgrades can save on energy bills and drive up a home’s value.

Unvented Roof spray foam insulation by Huntsman Building Solutions
Image courtesy of Huntsman Building Solutions

Installing insulation in an often-overlooked space – the attic – is one of the most effective ways to achieve an energy-efficient home. More specifically, make sure it’s medium-density closed-cell spray polyurethane foam insulation (ccSPF), because, as we’ll explain, it’s truly an efficiency powerhouse.

A leaky attic sends energy “through the roof”

Put as simply as possible, warm air rises to the top of the house and it leaks out through the attic and the roof, which is why this area is considered the most important part of the home to insulate. Air leakage can account for up to 40% of a building’s energy loss. Heating and cooling accounts for approximately 70% of the average energy bill. Not only that, traditional insulation can leave gaps collectively equal to the size of a basketball, and these gaps can also lead to excessive heat loss.

Efficiency powerhouse closed-cell spray polyurethane foam insulation (ccSPF)

It’s a big claim to say that an insulation can contribute in savings on heating and cooling costs by up to 50%, but a closed-cell spray polyurethane foam insulation (ccSPF) such as Heatlok Soya HFO absolutely can. It has the highest R-value in the industry at R-6/inch and even NASA has used ccSPF on their rockets.3 It adheres and conforms directly to common construction materials, regardless of shape and texture, making it perfect for areas which would be nearly impossible to insulate otherwise.

CcSPF has also been called “the perfect air and vapour sealing,” and has been tested and proven to do both in accordance with building codes (becoming a vapour barrier at 32mm or 1.25”). It even acts as a water-resistant barrier (WRB). All these features mean a tight building envelope, mold and condensation prevention and better indoor air quality (as it prevents pollutants and allergens from entering the home).

Why ‘unvented’ attics work in Canada

Most homes have ‘vented’ attics, with intake vents (under the eaves), which allow the cool air to escape, and exhaust vents (at the peak of the roof), which allow hot air and moisture to escape. Most commonly, ccSPF is sprayed on the attic floor in vented attics, to resist any transfer of airflow to the rest of the house.

However, for an attic to be used as a liveable space and/or a storage area, it must be unvented or “conditioned,” so that it’s the same temperature as the rest of the house. While there have been many debates on the subject, studies have repeatedly confirmed that if there is an airtight seal and moisture accumulation is controlled, vents are unnecessary, and ccSPF installed in unvented attic designs can work in all climate zones.

Besides becoming usable living space, other benefits of an unvented attic include:

  • Preventing ‘ice-damming’ by controlling heat loss through the ceiling plane
  • Preventing snow from being blown into the roof space
  • Fireproofing by preventing burning embers from entering the roof space (for example, during a forest fire)
  • Increasing roof durability (by preventing ‘roof uplift’ in areas prone to extreme weather)
  • Helping mechanical equipment to operate more efficiently and preventing duct leakage
  • Enabling more complex roof designs without compromising thermal, air and vapour layers.

Usually, unvented attics have unvented roof assemblies, but you can still construct an unvented attic and vent the roof. The first way is by installing backing to spray the foam on from the interior, leaving an airspace above the insulation and below the roof sheeting and shingles/membrane to ventilate. The other option is to spray the foam from the exterior, on the interior finish, while leaving an air cavity above the foam to ventilate.

 Let’s talk Heatlok Soya HFO

In addition to its uncontested energy performance, spray foams like the Heatlok Soya HFO closed-cell product uses the most environmentally conscious blowing agent ever produced: Honeywell’s latest Solstice® Liquid Blowing Agent technology. This gives it a zero-ozone depletion potential (ODP) and a global warming potential (GWP) of 1, which is 99.9% lower than current HFCs used in this industry.

Heatlok Soya HFO is made with recyclable material too, with each product containing a total of 22% recycled plastic and renewable soya oil. Just one resin drum contains up to 3,000 plastic bottles diverted from landfills. Since it adapts to all surfaces, shapes and volume, the installation generates zero waste and zero trash on the jobsite. Even the packaging is sustainable, as the system is sold in liquid form in returnable or recyclable containers.

Finally, Heatlok Soya HFO products are the first and only spray foam system with a product-specific, Type III EPD which is independently completed and verified. The objective assessment delivered through this EPD is key to ensuring an informed choice in the specification of sustainable insulation. It also contributes to USGBC LEED v4 credits and other green building rating systems.

The practice of proper application

From precise mixing of the chemical components to spray angle, technique is extremely important when working with ccSPF. Any reputable manufacturer should offer training courses like Huntsman Building Solutions, or even better, work with an authorized contractor.

Some costly mistakes to avoid (which should all be covered in training):

  • avoid spraying directly on chimneys (always leave a 3’’ gap between the chimney and the spray foam),
  • do not spray on rotten or humid wood (make sure it has been removed and repaired prior to the foam installation) and
  • make sure the roof is watertight prior to the foam installation.

Lastly, always go thicker than thinner, since roofing is where most of a home’s energy loss happens. It’s better to insulate properly now than come back in 10 years to add more. With ever-increasing certification requirements (such as ENERGY STAR® or LEEDS), stricter building codes and environmental laws, plus educated consumer demand for a more efficient home – closed cell spray foam could be just the solution for attics and the entire home.

Doug Brady with Huntsman Building Solutions Douglas Brady is the Chief Strategy Officer with Huntsman Building Solutions. He has been working in the spray foam insulations business for over 10 years, working both with application equipment and formulations.  Doug currently sits on the SFC Leadership Committee and is co-chair of the ICAA’s Trade Show committee. 

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