Give your house a hat

My bedroom was one of the coldest rooms in my old house. And it was cold in most part by design – there was virtually no attic space above it, which meant it had little ceiling insulation. Whatever heat got into the place soon went up and out.

Leigh Bond says he had the same problem with his home in Grandin a few years back. He couldn't live in his living room because it was always two to three degrees colder than the rest of the house.

"If we wanted to read, we went somewhere else."

But two years ago he renovated and put spray-foam insulation into the ceiling above that room.

"Now, my wife always sits in that room and reads."

Roof insulation is one of the biggest ways homeowners can shrink their energy bills and reduce greenhouse gas emissions. It's relatively cheap and simple, and most homes have huge room for improvement.

"Probably 40 to 50 per cent of your heat loss is through the roof," says Bond, president of the energy retrofit company Threshold Energies.

That's because heat rises and the ceilings of most homes are poorly insulated. A 1960s-1970s home like his will often have less than R20 insulation in their roof, which is less than what you find in modern walls. (R-values measure insulation; R0 is bad, R100 is great.)

Any home built today should come with at least R40 insulation in its roof, says Jerry Woywitka of Edmonton's Advanced Insulation Systems, who has been insulating homes since 1969.

"Any home that's built before 1987 is probably going to need an attic insulation upgrade," he continues – prior to then, builders weren't required to put any specific amount of insulation into their roofs.

You have three options when it comes to roof insulation, Woywitka says: fibreglass batts (chunks), spray foam, and cellulose.

Batts are expensive and leave many gaps in their coverage as you have to cut the chunks to fit, Woywitka says, while spray-foam isn't very cost-effective – you have to clear out all the old insulation first and then supplant the foam with new material. It can be useful in vaulted ceilings or low-slope roofs, he and Bond note.

Woywitka and Bond recommend cellulose, which is recycled newspaper treated with Borax to render it less flammable. This fluff is sprayed in using a blower, and adds about 3.4 "R" units of insulation per inch deposited.

Know before you blow

Most homeowners can check out their roof insulation by popping open their attic hatch and using a ruler, says Godo Stoyke of the eco-audit firm Carbon Busters. If you've got less than a foot of cellulose (equivalent to R40), you should probably add more.

How much is a matter of roof space and what you want. Stoyke and Bond recommend shooting for R50 (about 15 inches) as a good midpoint between what's required by the building code (R36 as of next year) and what you get in net-zero homes (R60 and up).

It'll cost you about $1,000 to $1,800 to hire a contractor to insulate a roof to that level, Stoyke says. You can also do it yourself for a few hundred bucks – Home Depot and other places carry the equipment.

Long sleeves and a high-quality facemask are a must when working with insulation due to the particulates, Stoyke says. You might want a helmet to guard against rafters and roofing nails as well as planks to keep your feet from making new holes in your ceiling.

Check for signs of condensation in the attic before you start blowing insulation. The space above your insulation needs to be very well ventilated, or you'll get ice and rot that will damage your roof, Bond says.

Your attic gets ventilation through the soffits, or the bits of roof that stick out over the outer walls. Use cardboard baffles or Styrofoam air chutes from the hardware store to keep these regions clear of insulation, Woywitka says.

Next, check if the recessed light fixtures sticking into your attic are IC-rated. If they aren't, that means they could catch fire if you pile insulation on them; you'll have to put a special cap over them before you blow, Stoyke says.

The low price of gas means that it will take 17 to 34 years to make your money back on roof insulation, Stoyke says.

But you'll likely see about a 20 per cent drop in your heating bill if you go to R50 from R20, Bond adds.

"It's pretty dramatic, considering how simple it is."

And it will make your home more comfortable, he continues.

"We can actually sit in our living room now, whereas we could not in the winter before."