Homeowners don’t usually think a lot about insulation. They know they need it, and they know–generally speaking, that ‘more is better’–but that’s about it.
What insulation does is reduce heat loss, in climates that get cold in winter, or heat gain from the sun and in hot climates. Thermal insulation will reduce the amount of energy you use to heat or cool your home.
Is it Cost Effective to Insulate?The right insulation system can save you money, reduce the amount of energy you use and make your home more comfortable. Keep in mind that installation costs (including changes to the framing, cladding, and finishes) are usually the most expensive part of an insulation project. The local climate has an impact on the cost-effectiveness of any insulating project.
Check the cost, heat loss and heat gain of all available options. Review all details to ensure that moisture movement is handled correctly. You can then select the right insulating system. When in doubt, consult a professional.
Insulation is measured in R value—that is the material’s resistance to heat loss. The higher the number, the better the material insulates. Building code specifies the minimum R value for attics and walls, depending on your regional climate. But that’s minimum code—and you know I always recommend going above and beyond code. And why wouldn’t you, especially when it comes to thermal insulation? It will always save you money over time
How much insulation you need, and what the best kind for you to use depends on your building’s design, your budget, what’s available in your area, and your preference.
But, R value alone won’t tell you what is the ‘best’ insulation. Heat loss is just one factor to consider. Another real concern is air movement. You might have R 40 worth of insulation in your attic, but if you have air leakage due to a poor vapour barrier you will have problems–problems with heat loss and problems with condensation. And condensation can lead to mould and rot.
It’s most important to make sure your building envelope is thermally broken—that it’s insulated evenly all the way around—to eliminate air leakage and hot meeting cold. Think of a cooler—the foam insulation in a cooler creates a thermal break that completely encloses the contents—without a gap–that might allow the cool air inside where you keep you drinks to escape. Or, more importantly, for the warm air from outside your cooler to sneak in melt your ice. That’s a thermal break.
Another example is a foam cup. If you were to put a glass of ice water on a sunny windowsill, what happens? Condensation will form on the outside of the glass because the glass is a poor thermal insulator and allows the cold liquid to meet the warm air. But, if you used a foam cup instead, you wouldn’t get condensation. The foam provides a thermal break—which is why you can comfortably hold a foam cup full of hot coffee and not be burnt.
As far as your house goes, in a cold climate you want to make sure the hot conditioned air you’ve got inside doesn’t escape. That’s air you’ve paid to warm up, and you don’t want to keep spending energy and money just to let it leak away.
In hot climates, the outside air is very warm, and we cool the inside air to make it comfortable. That warm exterior air combined with radiant heat from sun can heat the building’s exterior shell—the roof and walls—which will allow heat to transfer right through the building envelope. That makes it even more important to ensure that your house has good insulation. You still need that thermal break to keep the hot exterior air from meeting the cool interior air.
Types of Insulation
This is probably the most commonly used insulation. It comes in blanket-like pieces or rolls that are placed between the studs of your walls, or hung against poured foundations.
Batt insulation must not be compressed, since the trapped air in the fiberglass or mineral wool adds to the insulation value. Crush it or squeeze it into a cavity and you lose R value. If the builder or contractor is rushed or careless and just slaps it up and pushes it into spaces that are too small for the amount being used, or too big and leave gaps in the coverage—you know what’s going to happen: A loss of thermal insulation.
Also, the problem with batt insulation is that it is designed to fit between studs. So on those walls you will have cold spots where the studs are—as compared to where the insulation is. The R value of wood is not the same as that of insulation.
Most batt insulation is glass wool—made from spun fibers of glass. You need to be very careful when installing it—it itches and you do not want to breathe it in or get any in your eyes.
Minute particles of batt insulation can negatively impact your indoor air quality. I’d make sure my ducts were professionally cleaned before I moved into a newly built home that had fiberglass insulation, or after a reno that used it.
I use Roxul batt insulation made from mineral wool especially when I want a fire break and a sound barrier. Since it’s non-combustible, it can slow the spread of flame. And it’s mould resistant and water repellant. Made from basalt rock and recycled slag—it’s at least 40% recycled post-industrial material.
I’ve used blue jean batt insulation. The batts are made from recycled denim jeans that have been treated with Borax to make them rodent and insect resistant. It’s ‘green and clean’. You can find suppliers on the internet.
This is a stiff foam insulation that comes in sheets. Since it’s rigid, it can be compressed and not lose R value. That’s why I use rigid all the time in basements. It’s strong and provides the thermal break you need on basement floors and walls.
Rigid insulation doesn’t hold moisture and isn’t a food source for mould.
Sometimes you’ll see builders and renovators solve the stud cold-spot problem by adding Styrofoam insulation in a continuous layer on the outside of the house. That provides a much better, uninterrupted insulation and should be standard on any renovation if glass batting is being used between the studs. It’s a must-have if your builder is trying to go above code.
Loose fill or blown insulation comes in fiberglass and mineral wool, but cellulose is the best for blowing since it best fills irregular spaces. Cellulose is shredded paper fiber, treated with fire retardants. It will retain moisture—so if you have any leaks in your walls or roof that might lead to trouble since the cellulose won’t dry out completely.
Loose fill or blown insulation needs to be applied by a professional. The installer has to do it right—blowing it evenly and to the right depth. I don’t know how often I’ve seen loose fill insulation that’s been blown randomly into an attic space, covering all the soffit vents and cutting off the ventilation in the attic. This is a huge problem, and it can lead to ice dams and deterioration of your roof.
If you have no insulation in your wall cavities and you aren’t considering stripping back the wall to expose the studs and insulate, (which I’d recommend so you can get a look at wiring or whatever else might need investigating in there), you can have a contractor blow insulation into your walls. It won’t provide the same coverage and might leave some gaps, but it’s always going to be better than nothing.
Spray Foam Insulation
Spray foam insulation is a liquid product that expands and forms an excellent thermal barrier. It can be sprayed onto concrete, wood, drywall—you name it.
I think it’s the best possible insulation on the market—no question. Spray foam is effective overall at creating that complete thermal break in the building envelope. It covers everything so there’s no possibility of cold spots, voids or settling. There is no air movement between outside and inside, so there’s no possibility of condensation and, since it’s inorganic it won’t allow for mould growth.
Spray foam insulation must be applied by a professional installer.
Spray foams all need to have a barrier with a fire rating—like drywall—on the interior walls of the house. That’s because they release toxic fumes when exposed to flame.
There are two basic types of spray foam insulation: Open Cell and Closed Cell.
Open cell is softer and lighter and incorporates air for the insulator. It’s less costly than Closed cell, but it will retain moisture if it gets wet and it will require the use of 6ml vapour barrier—just like batt insulation.
Closed Cell is dense and rigid and will not retain moisture. I’m a huge fan of closed cell spray foam insulation. The best of all insulations on the market is closed cell foam. It wins on all counts—energy efficiency, indoor air quality and environmentally. It’s also its own vapour barrier (though you should check with local municipalities. Some inspectors still want to insist on vapour barrier, though they shouldn’t.)
There are two main kinds of spray foam—Polyicynene and Polyurethane. Both absolutely have to be applied by a specialized installer. Some CFCs are used in production and they off-gas for a time after application. All spray foam insulation is now being changed over to use eco-friendly propellants.
Walltite ECO is newest development in spray foam. You’ve seen me using the blue spray foam—it’s now purple, and it’s better. The formulation includes recycled plastic, renewable content and the blowing agent is zero-ozone depleting. Walltite Eco is the fIrst closed cell spray foam insulation to have the EcoLogo certificate–the most widely recognized third party audit and environmental certification.
Straw bale is really more a method of house building than a type of insulation, but what is unique about straw bale construction is its incredible insulation value. And it’s a cheap and renewable resource that is easily grown and harvested almost anywhere in Canada.
Indoor Air Quality
I talk a lot about insulation—that’s because it’s important. Good insulation is key to reduced energy costs and better indoor air quality.
Many homeowners prefer to not use fiberglass batts and are asking about natural, green and “healthy” options.
What do we mean by “healthy”? Are we talking ‘healthy’ from an indoor air point of view? Or healthy for the earth–as in green production and installation? All types of insulation-if you consider they cut down on energy use–are “green”, but some are better than others.
For an insulation to be ‘good’ it needs to give you energy savings. It needs to be inorganic so it won’t allow for mould growth. It can’t absorb moisture, or it’ll compress and lose R value. And it shouldn’t harm your indoor air quality with minute particles that circulate through the HVAC system.