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Insulation 101
By
Allan Britnell
Here's a primer on the various insulation options to consider that will make your home comfortable year-round and reduce both your heating and cooling costs.
With spring breezes slowly warming things up, it may seem like an odd time to start thinking about home insulation. But while we readily acknowledge insulation's role in keeping the cold air out of our homes in winter, you may not realize that it also does just as effective a job at keeping the heat out – and that pleasant air-conditioned comfort in – during the warmer months.
Batts
Batt
insulation is the type most familiar to homeowners. Whether it's
the famous pink fibreglass product made by Owens Corning (and
marketed by their equally famous mascot, the Pink Panther), the
Canadian-made, mineral wool-based product manufactured by Roxul
or, in rare cases, materials like cotton or wool, batts fill the
wall cavities of the majority of homes across the country.
Batt insulation's main attributes are its low cost (it's the cheapest option on the market) and ease of installation. Sized to fit snuggly between standard-spaced wall studs, it easily cuts with a utility knife.
Homeowners attempting a DIY insulation upgrade should make sure they don't try to cram too much into the wall cavity since compressing the material actually reduces the roughly R-3 per inch insulating value. You must also install a vapour barrier on the warm (interior) side of the wall before hanging drywall. In an attic, you can easily boost the R-value by simply laying batts over the existing material that's in place (R-value is a measure of the ability of insulation to stop heat flow; the higher the ability, the higher the value).
Boards
Styrofoam
insulation has been around since the 1940s when it was first
introduced by the Dow Chemical Company. Today, Dow's blue
Cladmate, along with several other brands of rigid board
insulation, is hidden beneath exterior siding, behind drywall
and below basement subfloors in countless Canadian homes. For
older homes with little or no insulation in the exterior walls,
adding rigid insulation before installing new siding is the
cheapest and easiest way to cut down on heat loss.
At about $2 per square foot, board insulation costs roughly three times as much as batts. But contractors like to use it because the lightweight material doesn't itch and it can easily be cut to shape around plumbing, electrical outlets and other obstacles. Homeowners appreciate the fact that it provides up to R-6 per inch in insulation value and, when the seams are properly taped, it also doubles as an air barrier – a key factor in reducing heat loss.
One caveat is that the ingredients in board insulation can be toxic when burned, so the building code requires you to cover these materials with drywall when installed in a living space (in other words, you can't leave board insulation exposed in an unfinished basement).
Blown and sprayed-in options
Blown insulation is a relatively cheap and effective way to insulate attics. In fact, pop your head up into your attic and, odds are, you'll find loose fill insulation made of fibreglass, mineral wool or cellulose providing you with about R-3 to R-3.5 per inch of material.
Blown insulation is also a great option for retrofit situations in under-insulated or uninsulated old homes by injecting loose-fill products into the exterior walls. The downside is that you need to drill two holes per wall cavity, either inside or outside, to get it there, so wall repair and repainting adds to the time and expense.
Alternatives are the spray foam insulation products. There
are DIY options on the market, such as Tiger Foam, but most foam
insulation is installed by trained professionals. The current
top-of-the-line products, closed-cell polyurethane foam, boast
an energy rating of up to R-6 per inch.
When we renovated our 90-odd year old home a couple years ago,
we opted to spray foam insulation on the underside of the roof
rafters (see "Making a Century Home Energy Efficient", fall 2010
issue). This enabled us to convert the space into a
climate-controlled storage area.
While foam insulation is the most expensive option – insulating
our attic with closed-cell foam cost us $3,500, about three
times what it would have cost to simply top up the existing
loose fill – the products' high R-value and air barrier
properties will soon make up the difference in reduced energy
bills.
