Carpet area vs built-up vs super built-up area

1.2.1 What is carpet area under the RERA Act?

Carpet area is the net usable floor area of an apartment. Section 2(k) of the Real Estate (Regulation and Development) Act, 2016 gives this definition. The definition excludes four things: external walls, service shafts, the exclusive balcony or verandah area, and the exclusive open terrace area. It includes the area under the internal partition walls of the apartment. So the walls between your bedroom and your living room count, but the outer walls of the flat do not. The Act also explains the two “exclusive” terms. An exclusive balcony or verandah is one that is attached to the usable floor area and is for the use of that allottee only. An exclusive open terrace follows the same rule. Carpet area is the only measure of flat size that the RERA Act defines. That makes it the one figure you can compare across builders on the same basis.

Part of the flat	Inside carpet area?	Basis
Rooms, kitchen, toilets and internal passages	Yes	Section 2(k): net usable floor area
Internal partition walls	Yes	Section 2(k): “includes the area covered by the internal partition walls”
External walls	No	Section 2(k): excluded
Service shafts	No	Section 2(k): excluded
Exclusive balcony or verandah	No, disclosed separately	Section 2(k) excludes it; Section 4(2)(h) requires its area
Exclusive open terrace	No, disclosed separately	Section 2(k) excludes it; Section 4(2)(h) requires its area
Common areas such as lobbies, stairs and lifts	No	Section 2(n) lists these as common areas

The definition covers an apartment. For a plotted development, rule 4(4) of the Karnataka RERA Rules, 2017 says the builder discloses the plot area as per the layout plan.

1.2.2 What do built-up and super built-up area mean?

Built-up area and super built-up area are market terms, and no law used in this chapter defines them. The RERA Act does not define either term. The Karnataka RERA Rules, 2017 mention them only once, in rule 4(3), as other bases on which builders sold flats. The next points describe general market practice, which Sachi did not check against a primary source. Builders often show built-up area as carpet area plus the area under the external walls, and sometimes plus balconies. They often show super built-up area as built-up area plus a share of common areas. These common areas can include lobbies, staircases, lift wells, clubhouse space and service rooms. But each builder chooses its own components and its own method to share the common areas among flats. Two brochures can show the same super built-up figure for flats with different carpet areas. So a super built-up number tells you the builder’s billing basis. It does not tell you how much floor space you get inside your front door.

Term	Defined in the RERA Act or K-RERA Rules?	What to treat it as	What to ask for
Carpet area	Yes, Section 2(k) of the RERA Act	The comparable size of the flat	The figure per unit, with the dimensioned plan
Built-up area	No (local building bye-laws not checked)	A builder-defined figure	The list of components, such as walls and balconies
Super built-up area	No	A builder-defined figure that usually includes a share of common areas	The common areas counted and the method of sharing them

The common areas themselves are defined. Section 2(n) of the RERA Act lists them. The list includes the project land, staircases, lifts, lobbies, common basements and terraces, parks, open parking areas, water tanks and community facilities.

1.2.3 What must a Karnataka builder disclose about flat area?

A builder in Karnataka must disclose the carpet area of every apartment type when it registers the project with K-RERA. Section 4(2)(h) of the RERA Act requires the number, type and carpet area of apartments for sale. The same clause requires the area of the exclusive balcony or verandah and of the exclusive open terrace, if any. So the balcony and terrace appear as separate figures, outside carpet area. Section 4(2)(i) separately requires the number and area of garages for sale. Section 2(y) defines a garage as a place with a roof and walls on three sides. It does not include open parking areas. Rule 15 of the Karnataka RERA Rules, 2017 makes the Authority publish these unit details on its website for each registered project. Rule 4(3) covers projects that were ongoing when the Act started. It says the builder must disclose apartment size based on carpet area. This applies even if the flat was sold earlier on super area, super built-up area or built-up area.

To see the filed figures, open Know Project Status on the K-RERA portal and search for the project. Compare the unit details with the brochure and the cost sheet. If the brochure shows only super built-up area, ask the sales team for the carpet area of the exact unit number. A builder that will not give the carpet area in writing is a reason to pause.

1.2.4 How do you compare two flats with different area figures?

Compare two flats on carpet area and on total price, not on the headline area. Divide the total price by the carpet area to get a price per square foot of carpet area. Do this for each flat, using the same set of charges in both totals. Then list the exclusive balcony, verandah and open terrace areas on separate lines, because the RERA Act keeps them outside carpet area. A large balcony has value, but you cannot use it the same way as a bedroom. Next, compare the room dimensions on the plans. Two flats with the same carpet area can have different layouts, such as a long corridor that uses floor space. Keep parking separate too. A covered garage and an open parking slot are different things under the Act. Last, check that each figure belongs to the same unit number in every document.

The example below uses made-up numbers to show the method. It is not data for any real project.

Item	Flat A	Flat B
Super built-up area in the brochure	1,500 sq ft	1,400 sq ft
Quoted rate on super built-up area	₹8,000 per sq ft	₹8,500 per sq ft
Total basic price	₹1,20,00,000	₹1,19,00,000
Carpet area from the builder’s written breakup	1,050 sq ft	1,000 sq ft
Price per sq ft of carpet area	about ₹11,429	₹11,900

Flat A looks larger by 100 sq ft in the brochure, but the carpet area difference is 50 sq ft. Flat B costs about ₹471 more per square foot of carpet area. If the balconies differ, add that difference as a separate line before you decide.

1.2.5 What is loading, and is there a fixed percentage?

Loading is the extra area that a builder adds on top of the carpet area to get its quoted area. Usually the quoted area is the super built-up area. The RERA Act and the Karnataka RERA Rules, 2017 do not use the word “loading”. They do not set a standard or maximum percentage. So any “normal” loading figure you hear is a market estimate, and you must not apply it to a new project. Loading also has two common formulas, and they give different answers for the same flat. In Flat A above, the loading is 450 sq ft. As a share of carpet area, that is 450 divided by 1,050, or about 42.9 percent. As a share of super built-up area, it is 450 divided by 1,500, or 30 percent. A builder and a broker can both be correct and still quote different numbers. Always ask which area the builder divides by.

Loading by itself does not tell you if a flat is good value. A project with a large clubhouse and wide lobbies can have higher loading. You pay for those common areas, and you also use them. The question is whether you get what you pay for. Ask the builder to list each common area included in its super built-up figure. Then match the list with the amenities on the sanctioned plan in the K-RERA filing. The carpet area and loading factor calculator on this page works from the figures you enter, so use the builder’s written numbers.

1.2.6 What should you check before you sign the agreement?

Before you sign, check that one carpet area figure appears for your unit in every document. Read the brochure, the cost sheet, the allotment letter, the agreement for sale and the K-RERA unit details. If the figures differ, ask the builder to explain the difference in writing before you pay more money. Check that the agreement states the carpet area and lists the balcony, verandah and terrace areas separately. Check the dimensioned plan of your unit, not only the floor plan of the tower. Section 14(2) of the RERA Act protects the disclosed plan. After the plans and specifications are disclosed to you, the builder cannot change your apartment’s sanctioned plan without your previous consent. The Act allows minor additions or alterations that you ask for. It also allows them for architectural or structural reasons, if an authorised architect or engineer recommends and verifies them and the builder informs you. But this exception excludes structural changes, such as an addition to the area or building, removing or cutting into any wall or partition.

Section 14(2) also covers the common areas. The builder needs the previous written consent of at least two-thirds of the allottees for other changes to the building plans or common areas. Sachi checked the 2017 text of the Karnataka RERA Rules, not later amendments. Sachi did not find a Karnataka rule that sets an allowed variation between the agreed and the final carpet area. Ask your lawyer how the agreement handles a change in carpet area at handover, and how the price changes with it.