Contributing to Energy Efficient Homes: Spray Foam Insulated Attics

Written by Doug Brady at Huntsman Building Solutions

With the current COVID-19 restrictions keeping us all at home more, Canadians everywhere are looking to either renovate or move.  Pandemic home renovations are definitely on the rise and 1 in 4 Canadians (26 per cent) are now seriously considering a renovation to their current home.  Additionally, nearly 1 in 5 Canadians (18 per cent) between the ages of 18-34 say the pandemic has accelerated their plans to purchase a home or invest in property.

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 is truly an efficiency powerhouse. 

The Problem: 

Insufficient attic insulation and sealing sends energy “through the roof” 

Put as simply as possible, warm air rises to the top of the house and 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 per cent of a building’s energy loss and heating and cooling accounts for approximately 70 per cent of the average energy bill.  Not only that, typical fibreglass and cellulose insulation can leave gaps collectively equal to the size of a basketball, and these gaps can also lead to excessive heat loss.

The Solution: 

Efficiency powerhouse – Closed Cell Spray Foam Insulation (ccSPF)

It’s a big claim to say that an insulation can save on heating and cooling costs by up to 50 per cent, 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 per inch and even NASA has used ccSPF on their rockets.  The product 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 so both in accordance with building codes (becoming a vapour barrier at 32 millimetres or 1.25 inches).  It even acts as a water-resistant barrier (WRB).  All these features mean a tight building envelope, mould and condensation prevention, and better indoor air quality (as it prevents pollutants and allergens from entering the home). 

To Vent or Not to Vent:

Why ‘unvented’ attics have become the new standard 

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.  It’s also been proven that ventilation has minimal effect on a roof’s temperature (the colour of the shingles actually makes a bigger difference).

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 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. 

One of the Greenest Insulation Choices You Can Make 

In addition to its uncontested energy performance, spray foams like the Heatlok Soya HFO closed-cell product use 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 per cent lower than current HFCs used in this industry.

Heatlok Soya HFO is made with recyclable material too, with each product containing a total of 22per cent 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, since the system is sold in liquid form in returnable or recyclable containers.

But it only works when applied properly.

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

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

  • Avoid spraying directly on chimneys (always leave a 3 inch 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. 

Finally, it’s always better to 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 you’re looking for – for attics and the whole home.

Contributing to Energy Efficient Homes: Spray Foam Insulated Attics

About the Author 

Doug Brady is the Vice President, Global Innovation and Product Management with Huntsman Building Solutions.