Article #106 - How Do I Enter Non-Uniformly Insulated Basement Walls in REScheck?
Some basement walls may have different insulation levels on different parts of the wall. The following example discusses the case where exterior insulation is used to cover only the below-grade portion of the wall; the exposed foot above-grade is uninsulated. Although this configuration can be entered in REScheck as shown in the example below, note that it is far more energy efficient to insulate the above-grade portion of the basement wall and protect the exposed above-grade insulation using any number of commercially available products.
Example 1: Wood Kneewalls
Assume that a basement is to be constructed with 3-ft-high wood kneewalls built on a 5-ft-high concrete foundation. R-13 insulation will be installed in the wood kneewall cavities, and R-5 rigid insulation will be installed on the concrete foundation walls.
The wood kneewalls are completely above grade and fully insulated. The concrete foundation walls are 4 ft. below grade and fully insulated.
Create one basement wall component for the wood kneewalls and enter the following information:
- Wall Height: 3 ft.
- Depth Below Grade: 0 ft.
- Depth of Insulation: 3 ft.
Create a second basement wall component for the concrete foundation and enter the following information:
- Wall Height: 5 ft.
- Depth Below Grade: 4 ft.
- Depth of Insulation: 5 ft.
Two basement wall components will be added to your list of building components. Provide the gross wall area of the wood kneewalls and enter the insulation R-value as R-13 in the Cavity Insulation R-Value field. Provide the gross wall area of the concrete foundation walls and enter the cavity R-value as R-5 in the Continuous Insulation R-Value field.
Example 2: Walk-Out Basement
Assume that an 8-ft. basement is to be built on a slope so that the front wall is 7 ft. below grade and the rear wall is totally above grade. The ground level along both side walls is sloped so that approximately 50% of each wall is below grade. The rear basement wall will be wood-frame construction with R-19 cavity insulation. The other three walls will be concrete walls with R-10 rigid insulation. All four walls will be fully insulated.
Create one basement component for the front wall and enter the following information:
- Wall Height: 8 ft.
- Depth Below Grade: 7 ft.
- Depth of Insulation: 8 ft.
The two side walls are at least 50% below grade, so they are entered as a basement wall component. If they were less than 50% below grade, they would be entered as an above-grade wall component. Therefore, create a second basement wall component for the two side walls and enter the following information:
- Wall Height: 8 ft.
- Depth Below Grade: 4 ft.
- Depth of Insulation: 8 ft.
The rear wall is fully above grade and should be entered as an above-grade wall using the Wall button. Note that the basement floor along this wall should be considered a slab-on-grade component. Create a slab component using the Floor button and enter the length of the basement floor along this wall in the Gross Area or Slab Perimeter field.
Example 3: Below-Grade Exterior Insulation
An 8-ft. high by 21-ft. wide foundation wall is 7 ft. below grade and is to be insulated using R-5 exterior rigid foam. The insulation will start at grade level and run down to the bottom of the foundation wall. There is 1 foot of uninsulated, exposed above-grade wall. The wall has no openings.
This wall is entered in REScheck by creating two basement wall components. The first component will be used for entering the uninsulated above-grade portion of the wall.
Select the Basement button and enter the following information:
- Wall Height: 1 ft.
- Depth Below Grade: 0 ft.
- Depth of Insulation: 0 ft.
The second component will be used for entering the insulated below-grade portion of the wall. Select the Basement button again and enter the following information:
- Wall Height: 7 ft.
- Depth Below Grade: 7 ft.
- Depth of Insulation: 7 ft.
After these components have been created, enter the gross area of each component and the R-value of the insulation used on the below-grade component.
Example 4: Draped Interior Insulation
Some builders choose to insulate the interior of basement walls with faced insulation batts. Some products have reinforced stapling tabs at the top and bottom of the batts for installation on furring strips using a hammer-stapler. They might also be power-nailed directly to a solid concrete or block wall or installed on pins glued directly to the foundation wall. The batts typically come in wide rolls and are sometimes installed on only the top four feet of the wall.
A solid concrete basement has 10-ft. high walls and is buried 9 ft. below grade. R-11 basement batt insulation is to be installed on the first four feet of the interior of the basement walls. Select the Basement button, select the Solid Concrete or Masonry option, and enter the following information:
- Wall Height: 10 ft.
- Depth Below Grade: 9 ft.
- Depth of Insulation: 4 ft.
With these inputs, the software will assume that the lower 6 ft. of the wall is uninsulated. The R-value of the uninsulated concrete wall is provided by the software and should not be entered by the user. After the basement component has been created, enter the sum of the gross area of all exterior basement walls in the Gross Area or Perimeter field and enter the assembly R-value (R-11) in the Continuous Insulation R-Value field. Note that the gross area equals the sum of the insulated and uninsulated areas.