The Exterior Wall System refers to the whole house wall system, usually including all four (or more) walls of the home. Only one system is used if all exterior walls have the same siding, construction, and insulation.

Adding a second wall system will allow you to separate the walls that might have different siding, different construction, and/or different insulation. For example, if there was an addition to the home after the year built which included extra insulation or different siding.

Please note that once a second wall system is added, the percent of total field is opened for both systems. So in looking at the house as a whole, what is the percentage of system 1 compared to system 2?

This is important in calculating the total square feet of the exterior walls. *If the percent of total is left blank you will get the following modeling error.

You can correct the percent of totals directly on the error message then click “complete modeling” to finish.

The modeling engine takes several different data points into consideration when modeling the total square feet of the exterior walls, and when determining the default R-value of the insulation.

When looking at the year built for example, if the home was built prior to 1950 it most likely had zero wall insulation. As building codes improve over the years, so will the likely amount of wall insulation. This helps determine the base R-values of the insulation.

The conditioned area and average wall height, are the most important when determining the total square feet of exterior walls, the length and width of the home would help fine tune that.

Floors above grade is also important. A true 2-story home (2 full stories with attic above) would have more exterior wall square feet than a 1.5-story home. It would be assumed that a 1.5-story home would have less wall space on the upper floor due to the pitch of the roof.

You have the option to edit the base values of the square footage and insulation after the first model.

There are two options for insulating the walls, Cavity and Continuous. Cavity insulates between the studs, while Continuous would be a rigid foam board usually attached to the outside of the exterior walls under siding.

It is very important to include the walls of the entire home - please do not just indicate the portion of the walls that need insulation, this would negatively affect the base values of the whole house modeling.

You are only allowed to enter two wall systems. If the home has more than 2 different types of walls you will need to just do some averaging.
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