Know your insulation

Choose the insulation option that's right for your home

By Allan Britnell

Insulation

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Whales have a thick layer of blubber to keep them from freezing in the cold depths of the ocean. Polar bears have blubber plus hollow hairs that trap air and help keep them warm. Heck, you probably have love handles helping to keep your sides warm. Unfortunately, your house may not be as well protected from the elements. As any homeowner who has done a little peeking behind walls or in the attic knows all too well, a lot of buildings are under-insulated. Here is a look at the options available when adding a protective layer to your home.

There are several indicators of inefficient insulation, including cold spots on walls or floors, mouldy patches or, that most pressing gauge, unreasonably high heating and cooling bills. There are a few things you can do to improve your home's insulation.

The high-tech approach: have an infrared photo taken of your house that shows areas of heat loss. If you're not prepared to go that far, just doing what you can to seal up holes in your home's protective layer by adding more insulation is a short-term cost that can more than pay for itself down the road. “It's like putting a toque on a house to keep the heat in,” says Andy Goyda of Owens Corning Canada.

Here are the cold, hard facts about the different types of home insulation.

Batts on a roll
Batts are the type of insulation that most DIYers are familiar with. They're cheap, have an R-value of three to four per inch (see “What R You Talking About?” on next page) and are easy to work with.

There are two main types of batt insulation on the Canadian market: fibreglass and mineral wool.

Mineral or rock wool insulation is, as the name suggests, made from stones. The Roxul brand is made from basalt and recycled steel. Mineral wool's two main advantages over fibreglass are increased fire- and water-resistance. The downside is cost. According to Trudy Hepburn, a senior sales rep with Milton, Ont.-based Roxul, mineral wool insulation costs about 10 per cent more than fibreglass. (Our own comparison shopping in the Toronto area found R-13.5 Roxul batts retailing for about $0.33/sq. ft. while Owens Corning batts with an R-value of 12 was selling at $0.26/sq.ft.)

Fibreglass is made from micron-thin strands of blown glass. Batts are sold sized for 2x4, 2x6 and steel studs on either 16" or 24" centres.

The key to successful application with either type of insulation is to fill all gaps snugly while not overcompressing the material. As with polar bear fur, insulation batts trap air, which inhibits heat transfer. You also need to install a 6-mil polyethylene vapour barrier on the warm side of the insulation.

If you're adding batts to your belfry, ensure you don't block the airflow to and from the soffit or roof vents. Check your local building code regarding setbacks from pot lights and chimney flues.

Unfortunately, familiarity breeds complacency: many don't take precautions when dealing with insulation. Particles can dislodge and irritate the skin, eyes and lungs. More significantly, according to the Canada Mortgage and Housing Corp., both fibreglass and mineral wool insulations are “possible carcinogens.” Wear goggles, a dust mask, gloves and long sleeves when working with insulation.

Board stiff
There are a number of different rigid insulations in varying thicknesses on the market. There are two common types. Expanded polystyrene is fairly loose white beads, not unlike the shipping material your tablesaw was packed in. It has an R-value of four. The other type is extruded polystyrene, the pink or blue boards you see in the hardware store. Extruded boards have an R-value of five. There are also boards made from fibreglass and other minerals, but these are less common. Others, such as Johns Manville's polyisocyanurate boards, are faced with foil sheathing.

In new construction, boards are often used in conjunction with batts to achieve required R-values. An R-5 board on the exterior combined with R-12 batts in the wall cavity gives an overall rating of R-17. “Putting foam on the exterior of a wall reduces the majority of the drafts that would come through the wall, particularly around electrical outlets,” says Goyda. Another bonus: installing the boards doesn't have the itch factor associated with batts.

The boards are easily cut with a utility knife and are simply nailed in place or glued directly to walls with adhesive. If the panels don't interlock, the seams should be taped. And, as with batts, you need to install some vapour barrier on the warm side of interior walls.

It is important to note that the fumes from burning rigid insulation are toxic, so cover them with a fire-resistant material such as 1/2" gypsum board. Then there's the material cost. Polystyrene boards with an R-value of eight or less retail for $0.50 to $0.75 per sq. ft.

Canned heat
There are two types of canned foam insulation: polyurethane and latex. Both are easy to use but have very different properties. Latex remains pliable after installation and can be cleaned up with water. You can remove uncured polyurethane foam with acetone, but once it gets on your fingers you're stuck with it until it wears away. Use gloves.

WHAT R YOU TALKING ABOUT?
The “R” in “R-value” stands for “resistance” to heat transfer. The higher the number, the better the insulation will be at keeping the heat in (or out). In Canada, we also use the metric equivalent, RSI. (If you're feeling patriotic and would like to convert, RSI = R x 0.1761.)

You can use foam to seal air leaks in a number of areas around the home, such as where the sill plate sits on the foundation, behind baseboards and window trim, and wherever pipes or wiring breach exterior walls.

Polyurethane is the denser of the two and has a slightly higher R-value (five versus 4.5 for latex). Overfilling cavities can lead to bowed frames or cracked windows. Choose the formulation based on the job and size of gap you need to fill.

A 340-gram can of either yields a 1/2" bead about 200' long and sells for $6 to $8.

Spray it
Spray-applied foam insulation installation is a job for licensed professionals. There are two types of spray foam, polyurethane (the same material as the stuff in a can) and polyicynene (sold under the brand name Icynene).

Both can be used in retrofits where no insulation exists: small holes are drilled in a wall and the two-part epoxy is injected into the wall cavity. They're also used as an insulating air barrier in attics or wall cavities in new construction. While significantly more expensive than batts or boards, the cost is offset by long-term energy savings.

Polyurethane, with an R-value of six per inch, is also a good option for crawlspaces. Installers spray the sticky foam directly to the underside of the sub-floor. Polyurethane acts as its own vapour barrier and, at least anecdotally, seems to be rodent-proof.

Icynene has a lower R-value (R-3.6 per inch) but contains no CFCs or HCFCs.

On the loose
Loose fill, or blow-in insulation is another job for the pros. Like batts, it can be made of fibreglass or mineral wool. There are also cellulose (paper-based) products. All have R-values around three to four per inch.

Loose insulations are another good option for hard-to-access areas such as attics and uninsulated wall cavities. Settling can be a problem with loose fill insulation in walls where, over time, it can sink to the bottom-leaving uninsulated voids at the top of walls. The main problem in attics is uneven distribution.

Healthy house
Asbestos and urea-formaldehyde Foam Insulation (UFFI) are two names that can strike fear in the hearts of homeowners. More recently, some vermiculite (loose fill) insulation has also come under scrutiny. A brand named Zonolite, sold in Canada until 1984 and used for retrofit attic insulation, may be contaminated with a carcinogenic form of asbestos.

The good news is that if you leave these types of insulation alone, they'll return the favour. Current research shows the health risks only materialize when these materials are disturbed and particles are dislodged and become airborne.

In fact, Bill Crawford of the Canada Mortage and Housing Corporation says you should take precautions with all types of insulation. “It doesn't matter if it's asbestos or fibreglass or mineral wool, you don't want to go messing around with this stuff. They all have small fibres that can get into lungs,” he says.

If you are planning on doing renovations and are concerned that asbestos or UFFI may be present, get an inspection before you begin. You can find contractors in the Yellow Pages under “Asbestos Removal.”

Insulated concrete forms
picConcrete is wonderful stuff in many ways, but warmth and insulation properties aren't among the list of advantages. At least, not until recently. But now, something called “insulated concrete forms” (ICFs) are eliminating the traditional thermal drawbacks of concrete by boosting energy efficiency and making poured concrete more of a DIY possibility.

 

 

Manufactured by a handful of companies across Canada, ICF systems use rigid pieces of foam as one-time forms for containing concrete used in both foundation walls and above-ground applications. Inner and outer form walls are typically assembled like Lego blocks, and held together with horizontal plastic connectors called “webs.” These webs also support lengths of steel-reinforcing rod that strengthen the completed wall.

Unlike traditional wooden forms, ICFs remain in place permanently, offering effective insulating characteristics. If you're thinking of pouring any kind of wall as part of a home-improvement project, ICFs eliminate the problem of what to do with a bunch of concrete-covered plywood after the work is done. Wood or plastic strips are typically embedded in the foam while it's manufactured, offering areas into which screws can be driven to secure drywall or siding. ICFs are still marketed mostly to professionals, although one brand, Formtech (1-877-848-6155), is now available through selected Home Depot stores.

Most ICFs sold in Canada use two layers of 2 1/2" expanded polystyrene foam-one inside and one outside. This yields a total insulating value of R-20, not including the concrete, drywall and whatever is applied as an exterior wall surface. And while this doesn't sound any better than a traditional 2x6 stud wall insulated with fibreglass, it actually is. Since the foam insulation forms a continuous thermal barrier, it beats frame walls that only have a value of R-5 wherever studs and plates extend from the inside surface of a wall to the outside. Also, ICF walls don't need a vapour barrier, while still eliminating all possibility that internal wall condensation can set in. Although it's hard to quantify accurately, six or eight inches of concrete also boosts the wall's thermal performance by increasing its mass as well as its sound-blocking ability.


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