INSULATING YOUR HOME AND UNDERSTANDING THE TYPES OF MATERIALS USED
As homeowners, we haven't given much thought to what's behind our walls. But as we begin to build our new home from the ground up, proper insulation of the exterior walls became top of mind. Especially in a Passive House, a well insulated home is key to energy efficiency. Besides the perk of lower energy bills, this means a more comfortable home - warm in the winter and cool in the summer.
What is an R-Value?
The effectiveness of insulation is measured by the resistance value, often referred to as the R-Value. This is based on the insulation material's ability to resist heat flow. The higher the R-value, the better the material insulates.
There are a variety of insulation materials to choose from when insulating a home. Each type of insulation has advantages and disadvantages and offers varying environmental benefits. The commonly used materials are fiberglass, mineral wool, cellulose and polyurethane.
Fiberglass insulation is the "pink stuff" most people think of when they think insulation. This is one of the most common form of "batt" or "blanket" insulation that comes in rolls. It is made of very fine flexible glass fibers woven together. It also comes in loose-fill shreds, which is blown into tight spaces and cavities.
You can find fiberglass insulation in most home improvement stores. It is relatively inexpensive and easy to install. It's R-value is 2.9 - 4.2 per inch. It is often used for insulating floors and flat ceilings.
The downside to fiberglass insulation, is that it can leave gaps where air can circulate and this may lead to condensation.
Mineral wool insulation is usually yellow or brownish in color. Like fiberglass, it is also a common form of batt insulation that comes in rolls but can also come in loose-fill shreds. It is made from fibrous materials that are formed by melting rock and spinning them into fibers. As a result, it looks and feels like wool.
This insulation is extremely fire-resistant, sturdy and long lasting, which makes it suitable for exterior walls and attics. With these additional properties, it tends to be more expensive than fiberglass.
Mineral wool insulation has an R-value of 3.0 - 3.2 per inch.
Touted as one of the best eco-friendly insulation, cellulose insulation is made from 85% recycled material, typically newspaper. The other 15% is a composition of chemicals that makes it fire, pest and mold resistant. It comes as loose-fill shreds that can be blown into wall cavities, which makes it a good choice for irregularly shaped areas.
This insulation has an R-value of 3.4 - 3.6 per inch, which is higher than that of fiberglass and mineral wool.
One downside to cellulose insulation is it's shorter lifespan compared to fiberglass. Since it is made of recycled newspaper, it degrades over time faster and is susceptible to water damage by condensation and leaks.
Polyurethane is the material used in what most people call "spray foam". This type of insulation is produced as either open-cell or closed-cell and each have different qualities.
Open-cell is sponge-like and has a lower R-Value of 3.5 - 3.7 per inch. Whereas closed-cell is rigid and has an much higher R-Value of 5.5 - 6.8 per inch.
Of the two, closed-cell is much more expensive due to its rigidity and higher R-Value. Therefore, it is commonly used on exterior walls because it offers greater structural strength and results in less wall movement by wind or vibrations. The higher R-Value offers greater insulation value for relatively lesser wall thickness. This allows for more usable floor space inside the home.
Thanks to home improvement celebrities that show off spray foam as a great insulation option, it is becoming increasingly popular. But buyer beware, spray foam insulation can lead to off-gas and health problems if not installed correctly by professionals. Unlike the other types of insulation, spray foam is difficult and costly to remove.
Insulation Materials Banned in Canada
Good insulation makes a home energy efficient, but not all insulation materials are safe. In Canada, insulation materials consisting of asbestos, formaldehyde and vermiculite have been banned. These materials were widely used in the past and can still be found in older homes, but not in newer homes.
Asbestos, when released into the air, is linked to lung cancer when inhaled. Urea Formaldehyde Foam Insulation (UFFI) became unpopular after being associated with health problems such as headaches and nose bleeds. Vermiculite, while not known to be a health risk, is also banned because of its contamination with asbestos.
All Things Considered...
While there are several common options to choose from when it comes to insulation, batt insulation using fiberglass in interior areas and mineral wool on exterior walls works best for our particular design. Spray foam, while being a good insulator, would cost an extra $150,000 to insulate the entire house and is simply not within our budget. Nor does it translate to direct dollar value for our new home. Coupled with the potential off-gases and health risks, we would rather err on the side of caution. Using thicker layers of batt insulation can achieve a higher R-Value and that is way we will go.
Aside from these most common types of insulation materials, there are other options available in the market, particularly when it comes to pre-assembled wall sections or building blocks.
Whichever insulation you choose, at the end of the day, a comfortable and healthy home is what matters!
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