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Construction Profile - Above Grade Wall Hints


There are many types of Above Grade Wall types in Cool Calc. Below are some helpful hints when selecting above grade wall types:

Primary Structure - Most contractors or homeowners will know the "primary structure" type used to construct the home. Some structure types are more prevalent in certain areas of the country than others. For example, "block" or "concrete" structures is more prevalent in places such as Florida and Arizona, while wood framing is more prevalent in the Northeast. If you do not enter a primary structure type, Cool Calc will automatically select one based on the most common structures found in that particular state.

Cavity Insulation R-Values - It is often difficult to determine the R-value of cavity insulation because unlike ceiling insulation that can be viewed from the attic, cavity insulation for walls is hidden behind drywall. There are a few options to determine R-Values in Cool Calc.

Option 1 - Use Code Year: Let Cool Calc automatically determine the R-value based on the year the house was built. If the walls of the home were renovated after the home was built you can update the code year and Cool Calc will automatically update the R-values according to what building code required at that time.

Option 2 - Manually Enter R-value: If you know the R-value of the insulation used in the walls you can enter it. If you do not, here are some helpful hints:

First determine the thickness of the wall. An easy way to determine if a home is 2x4 or 2x6 construction is to measure the thickness of the wall at one of the exterior doors.

Cellulose Insulation (typically made from recycled paper) has an R-value of about 3.8 per inch. Fiberglass  insulation is closer to 3.2 per inch. So 2x4 walls (which are really only 3.5" wide) typically have R-values between R-11 and R-15 (3.5" x 3.2 = 11.2 and 3.5" x 3.8 = 13.3). 2x6 walls are typically in the R-19 to R-21 range. 

If the outside walls have spray foam insulation, a good rule of thumb is that closed-cell spray foam has an R-value of about 6.5 per inch. However, most spray foam is only applied in a 3" thick layer since applying more than three inches can cause issues when drying.

Board Insulation R-Values - Some primary structures do not allow for cavity insulation. In addition, some building codes require a total wall R-value that exceeds what can fit in a cavity. In those instances external board insulation is applied to the outside of the home below the siding. This is called board insulation.


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  • Avatar
    Ethan Brunson

    When adding a room and its walls, which floor level do you include the height of the floor between levels?
    Also, when adding an upper level room, are you to add the absolute height from grade or the height from the finish floor of that particular level?

  • Avatar
    Philip Gonzalez

    I have the exact same question...Also, when adding an upper level room, are you to add the absolute height from grade or the height from the finish floor of that particular level?

  • Avatar
    Craig Homem

    Same question

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