Which of the following is NOT a method for performing area takeoffs?

The correct option indicates that estimating the total area based on building volume is not a recognized method for performing area takeoffs. Area takeoffs specifically involve measuring surface areas directly to determine the amount of materials needed for construction or each phase of the building process, particularly related to air barriers.

Each of the other methods listed is directly linked to concrete measurements of specific parts of the building. Measuring the first floor area provides an exact calculation based on actual floor dimensions. Measuring the perimeter of the air barrier boundary and multiplying by the floor height gives a precise area for the vertical elements of the air barrier. Measuring the roof area and accounting for soffits focuses on obtaining accurate roofing measurements, essential for assessing materials related to the air barrier system.

In contrast, estimating total area based on volume can lead to inaccuracies because it does not account for the unique architectural features or variations in dimensions across different areas of the building. It relies on generalization rather than precise measurements, which is not appropriate for effective area takeoffs in the context of airtightness and building envelope considerations.