There are a variety of different types of insulation boards that can be used as the insulation in EIFS. By far the most common exterior toronto insulation is Type-I (1) EPS (Expanded PolyStyrene). This is the white insulation boards you typically see being installed, as well as what is found at hardware stores such as home depot. Most EIFS manufacturers require that the EPS be purchased from them when using their system, for a variety of legitimate reasons. The EIFS manufacturers purchase the polystyrene in bulk, and of a certain grade/quality. That being Type-I (1 pound per cubic foot), Virgin (no recycled content) and in 2’x4′ sheets of your specified thickness.
Polystyrene can be manufactured in a variety of densities (referred to as the “type”). Some can go as low as 0.5 pounds per cubic foot, meaning that they are half as dense as 1 pound per cubic foot – and offer much less insulating value. Some manufacturers sell lower densities because it is less expensive, and the average consumer is not aware that they are getting less insulating value for their dollar. On the other end of the spectrum, it is also possible to get denser styrofoam – Type-II or Type-III (2 lbs per cubic foot and 2.5 lbs per cubic foot respectively) which offer more insulating value per inch.
Why 2’x4′ sheets? Simply, they are easier to work with, and make the system more crack resistant by providing many points at which the system may make minor shifts without cracking the base coat or finish coat.
Generally, the Type-I polystyrene you get from an EIFS manufacturer offers an R-Value of 3.71 per inch. This becomes important when you are trying to achieve the maximum rebate from the Retrofit Rebate Program. The Retrofit Rebate Program will grant upwards of $3,750 for adding R-9 to the exterior of your walls – which EIFS does better than any other material. To get to R-9 from 3.71/inch, you require almost exactly 2.5″ (3.71 * 2.5 = R-9.275). It becomes very important to specify this to your contractor when soliciting quotes, because typically 1.5″ or 2″ is specified by default – which will only get you the $2,250 rebate. Generally, the price difference contractors will ask for to go from 1.5″ to 2.5″ is about $700-$800, but will get you an additional $1,500 in rebates. Well worth the investment.
Other Insulation Boards
Other types of insulation boards that are sometimes substituted for EPS when certain factors require them. For example, when adding insulation to the exterior of a wall, that is located between houses that are close together (like downtown Toronto) – one wants to minimize how far the insulation comes out from the wall. In this situation, a denser insulation such as XPS (Extruded PolyStyrene – pink or blue insulation) can be substituted. While 1.5″ of XPS typically is enough to achieve R-9 insulation, contractors demand a higher price to install it as it takes a little more work and is itself more expensive to purchase.
Sometimes fire-resistance is an issue (particularly downtown, and especially on commercial projects). In this situation, Roxul Mineral Fiber Insulation can be used. While this is an option, it’s an expensive one and difficult to do correctly. Typically it is recommended that the fire-rating is achieved by the drywall/substrate by using Type-X Gypsum boards or Cement Boards and installing a regular, EPS EIF system over it.
As always, consult with the EIFS manufacturer before making any decisions to validate any information you find on this site, or that your contractor gives you.