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Construction Profile - Above Grade Wall Hints

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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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Comments

  • 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

  • Avatar
    Michael Binder

    If I want to enter my own R value like you mention in Option 2 above, how do I do that? I don't see a way to manipulate that value.

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    Cool Calc Support

    The option to manual enter R-values was removed in version 3 of our application, but will be added back in our next version. What is the total wall r-value you are looking to achieve? There are options to select r-values up to R-36 walls in the current version.

  • Avatar
    Michael Binder

    Thank you. I have started working on passive houses with very high R-values up here in MN, so the walls are R-36. I anticipate they may go up so having the ability to enter an even higher R-value would be helpful. Thanks for the response!

  • Avatar
    Cool Calc Support

    Thanks for the feedback. For now, I would select "Insulated Concrete Form" walls which allows for higher R-values. The r-value is more important that the actual wall type.

  • Avatar
    Taurean Ryan

    Sonif I can't manually input walls R value how do I know that the load calculation is correct?
    I need to get R19 insulation in wall.

  • Avatar
    Cool Calc Support

    If you change the above grade wall framing from 2x4 to 2x6 you can select R-19 cavity insulation. 2x4 walls only support up to R-15.

  • Avatar
    milo brown

    I have a 2 story home with a 1776 sq ft unfinished basement i wont to do a load calc on the basement how would i perform a load.

  • Avatar
    Cool Calc Support

    I would recommend to specify that the home is a 2-story home with finished basement in the dwelling info screen if you intend to finish the basement. Then when you get to the dimensions section, trace the proposed living area on all three levels (this will automatically remove the ceiling load above the basement and calculate proper infiltration). However, when you get to the HVAC Systems section, add a system and answer "No" to the question that asks if the system serves all rooms. The program will then prompt you to select the rooms the system serves, and you would only select the basement.

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