Builders commonly use it to price a home at sale, and it is commonly quoted as around a quarter to a third more than the built-up area, though this is a convention, not a rule set by law. Rental listings mix area terms more loosely than sale listings do, so a rent quoted against a super built-up figure can look smaller per square foot than it really is. We always ask which area a quoted rent is measured against.
The number
Commonly quoted as around 25 to 30 percent more than the built-up area. This is a builder convention, not a figure set by law.
Sources
Where it comes from. Level 1 is a government or court page, level 2 established press, level 3 a portal's explainer, which gives only what is commonly quoted.
- BricknBolt, carpet area, built-up area and super built-up area guide, https://www.bricknbolt.com/blogs-and-articles/construction-guide/understanding-carpet-area-built-up-area-super-built-up-area, level 3