Partially below grade walls

My bottom floor is about 3ft below grade and 5ft above grade. The above grade part is framed with 2x4 and insulated with batt insulation in the cavity between the studs. Exterior is brick. The below grade part is not framed, however it is finished. But there is no insulation like the above grade part. I can't figure out the best way to represent this...?

Should I create separate walls, one with 5 ft high ceiling, that is "above grade", and another, 4 ft high ceiling, below grade? If I use the correct ceiling height for the below grade section it does not let me select insulation for just the above grade area and the resulting heat loss is very high. And I don't want to include the entire wall as being framed and insulated since the below grade section does not have cavity insulation.

Matt O'Connell December 26, 2017 22:53

Official comment

Hi Matt,

That is a good question.

If you are performing a block load calculation I would recommend creating a single room with location = Below Grade, then entering 3ft for the height below grade and 5ft for the height above grade. This will be used to determine your infiltration calculations.

You can then create a below grade wall that is entirely below grade (match the ceiling hight to the below grade portion) and an above grade wall that is entirely above grade (match the ceiling height to the above grade portion). This will allow you the flexibility to have different insulation values for each. The only problem is the tables in the Manual J book are listed in 2ft increments, so you will not be able to select 3ft below grade (you will need to choose between 2 and 4).

Best Regards

Bill

Cool Calc Support December 27, 2017 02:09

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2 comments

-1

How do I perform a load calc for basements that are going to be finished living space?

Angelo Gary January 29, 2021 14:13 -1 votes