How to Read a Floor Plan Before You Buy: Light, Air, Layout

Updated October 22, 2026

A brochure floor plan is drawn to sell. Furniture is shown smaller than real life, balconies look generous, and the compass arrow is often missing. Yet the plan is still the best tool you have for judging a flat before it exists, or before you spend a Saturday visiting it.

This guide explains how to read a floor plan for the things that matter most in Delhi NCR’s climate: sunlight and heat, cross-ventilation, wasted space and whether your furniture will actually fit. It also covers which drawing you should be reading in the first place.

Start with the right drawing

Builders produce several kinds of plans. The glossy brochure plan is marketing material. The plans that bind the builder are the sanctioned plans approved by the development authority.

Under section 11(3) of the Real Estate (Regulation and Development) Act, 2016, the promoter must make the sanctioned plans, layout plans and specifications available to the buyer at booking and allotment, by display at the site or as the state regulator specifies. Section 14 requires the project to be built according to those sanctioned plans. Once they are disclosed to buyers, the promoter cannot make changes beyond minor ones without the buyer’s consent for their own flat, and needs the written consent of at least two-thirds of allottees for other changes to the building plans. The Act’s definition of minor changes excludes structural work, added area, changed height or closing access routes.

So ask for, and compare against, three things:

the unit plan of your exact flat type, with dimensions;
the tower or floor plan, showing where your flat sits relative to lifts, staircases, shafts and neighbours;
the site or layout plan, showing tower positions, open areas, roads and which way is north.

Projects registered with UP RERA or Haryana RERA upload key documents on the regulator’s website. Cross-check that the plan in the brochure matches what was filed. If you are shortlisting, the project listings on ADiHomes show the RERA number to look up.

Read the area figures before the rooms

RERA defines carpet area as the net usable floor area of a flat, excluding external walls, service shafts, exclusive balconies or verandahs and exclusive open terraces, but including internal partition walls. Builders must declare carpet area when they register a project, along with the separate balcony and terrace areas.

Many NCR builders still quote prices on super area (also called saleable or super built-up area), which adds a share of lobbies, lifts, staircases, the clubhouse and other common areas. The gap between the two is often called loading.

Worked example: compare price per carpet square foot

Item	Flat A	Flat B
Super area	1,500 sq ft	1,400 sq ft
Carpet area	1,020 sq ft	1,050 sq ft
Loading (super minus carpet, as % of carpet)	47%	33%
Quoted rate	₹7,000 per sq ft super	₹7,400 per sq ft super
Total basic price	₹1.05 crore	₹1.036 crore
Price per sq ft of carpet	₹10,294	₹9,867

Flat B looks dearer on the headline rate, but it gives you more usable floor and costs less per square foot you can actually use. The figures are illustrative. Always do this calculation with the carpet area stated in the RERA filing and agreement.

Find north, then think about the sun

Delhi NCR sits at roughly 28° to 29° north. The national residential energy code, Eco-Niwas Samhita (ENS) 2024 from the Bureau of Energy Efficiency, places New Delhi in the composite climate zone: very hot summers, a humid monsoon and cool winters. Summer heat peaks in May and early June, often with hot, dry westerly winds (the loo).

The sun’s path explains which walls suffer. In the northern hemisphere, the winter sun rises in the south-east, stays low in the southern sky and sets in the south-west. The summer sun rises in the north-east, passes high overhead slightly to the south, and sets in the north-west. In practice this means:

North-facing windows get steady, glare-free daylight and the least direct sun.
South-facing windows get winter sun, which is welcome. In summer the sun is high, so a balcony or overhang above shades them well.
East-facing rooms get morning sun, which is pleasant for bedrooms and kitchens.
West and south-west facing walls and glass take the low, hot afternoon sun in summer. It comes in at a low angle that overhangs do not block easily.

ENS puts numbers on this. It uses an orientation factor to weight how much solar radiation a wall receives. For latitudes at or above 23.5° north, which covers NCR:

Wall faces	ENS orientation factor	What it means for a flat
North	0.550	Least solar heat; good for living rooms and study
North-east	0.829	Mild; morning sun in summer
North-west	0.821	Mild, but late summer evening sun
South	1.089	Easy to shade with a balcony above
East	1.155	Morning heat, cooler by afternoon
West	1.143	Afternoon heat when rooms are warmest
South-west	1.202	Hot; large glass here needs shading
South-east	1.211	Highest factor; shade large openings

A wall facing north receives about half the weighted solar load of one facing south-east or south-west. That does not make north the only good answer. A north-facing living room with a south-facing balcony shading a bedroom can work well. The point is to check where the large glass is. A floor-to-ceiling window on a west or south-west wall, without a deep balcony in front, will mean hot summer afternoons and a higher electricity bill.

If the brochure has no north arrow, take it from the site plan, or use a phone compass during a site visit. In a tower with four or more flats per floor, the same flat type can face different directions on different sides, so check your exact unit number.

Check for cross-ventilation

Cross-ventilation happens when air enters through an opening on one side of a space and leaves through an opening on another, ideally the opposite side. It cools rooms and clears cooking smells and indoor pollutants without using power, which matters in NCR’s spring and post-monsoon months.

On a plan, look for:

windows or balcony doors on two different external walls of the living-dining space;
bedrooms with windows on two walls (corner bedrooms), or at least a window that faces an opening across the flat;
a straight path for air through the flat, not one blocked by a closed kitchen and a long internal corridor;
flats with exposure on only one face, common in the middle of long corridors, which ventilate poorly.

How much openable window is enough?

ENS 2024 sets a mandatory minimum openable window-to-floor area ratio for its compliance: 12.5% for the composite climate, which is drawn from the National Building Code of India 2016. It counts only the part of a window that actually opens. Its default assumptions are 90% of the opening for a casement window, 50% for a two-pane sliding window and 67% for a three-pane slider.

Worked example: a 3BHK with 100 sq m of carpet area should have at least 12.5 sq m of openable area. If every window is a two-pane slider, the total window opening needs to be about 25 sq m to reach that, because only half of each window opens. A plan with mostly two-pane sliders and few balcony doors may fall short. Whether ENS is mandatory for a particular project depends on how the state has adopted it, but it is a sound national benchmark for buyers.

ENS also asks for a separate opening or ventilator, besides the window, for an exhaust fan in kitchens and bathrooms. A bathroom with no external wall relies entirely on a duct, so check that a shaft is marked next to it.

Spot wasted space

Every square foot of corridor is a square foot you pay for but cannot furnish. Look for:

Long internal passages leading to bedrooms. A passage 1 m wide and 5 m long uses 5 sq m, about 54 sq ft, of carpet area.
Odd-shaped rooms, angled walls and splayed corners that make furniture hard to place.
Doors on every wall. A bedroom with a balcony door, a bathroom door, a wardrobe and an entry door may leave only one wall for a bed.
Columns and shafts intruding into rooms. Brochures often omit or shrink them. The sanctioned or structural plan shows them more faithfully.
Foyers that are generous on paper but too narrow for a shoe cabinet and a door swing together.

A useful test is to estimate how much of the carpet area goes to circulation. If corridors and lobbies inside the flat take more than about a tenth of it, compare with other layouts at the same size.

Test whether your furniture fits

Brochure plans often draw beds, sofas and dining tables smaller than standard sizes. Do your own check:

Write down the internal dimensions of each room from the plan, not the overall area. Confirm whether they are wall-to-wall or include wall thickness.
Measure your own bed, wardrobe, sofa and dining table, including clearances. You need room to open wardrobe doors and to walk around a bed.
Draw the room to scale on squared paper (for example, 1 cm for 30 cm) and place your furniture.
Mark door swings and window positions. A window low on the wall where the bed must go is a common conflict.
Check the kitchen for a straight counter long enough for a hob, sink and some workspace, plus space for a refrigerator. Check whether a washing machine has a dedicated utility space.

Balconies deserve the same test. A balcony that is under about 1.2 m deep may hold plants and a clothes stand, but not a small table and two chairs.

Look beyond your four walls

The tower and site plans answer questions the unit plan cannot:

Facing what? A west-facing flat that looks onto another tower 15 m away will be shaded, but it will also lose privacy and views.
Next to what? Flats beside lift cores, garbage chutes or electrical rooms can be noisier.
Flats per floor and per lift. More flats sharing two lifts means longer waits at peak hours.
Which floor? Top floors under a roof take more summer heat unless the roof is well insulated. Lower floors in dense projects may get less daylight.

If you are comparing projects in a particular area, such as those in the new projects in Noida or new projects in Gurugram lists, apply the same tests to each shortlisted layout so the comparison is like for like.

A quick floor-plan checklist

Is this the sanctioned plan, and does it match the RERA filing?
What is the carpet area, and what is the price per carpet square foot?
Where is north? Which walls carry the big windows?
Is there large glass on a west or south-west wall without a balcony in front?
Does the living area have openings on two walls for cross-ventilation?
Roughly how much openable window area is there compared with the carpet area?
Do kitchens and bathrooms have exhaust openings or a shaft?
How much of the flat is passage?
Do your bed, sofa and wardrobe fit with doors open?
What does the flat face, and what is next to it on the floor plate?

Take the plan on your site visit, stand in the rooms at different times of day if you can, and note where the sun falls. A good layout will save you money and discomfort every summer for as long as you live there.

Frequently asked questions

Which floor plan should I rely on, the brochure or the sanctioned plan?

The sanctioned plan approved by the authority. RERA requires the promoter to make sanctioned plans, layout plans and specifications available at booking and to build according to them, while brochure plans are marketing material.

What is carpet area under RERA?

RERA defines carpet area as the net usable floor area of a flat, excluding external walls, service shafts, exclusive balconies or verandahs and exclusive open terraces, but including internal partition walls.

Which direction is best for a flat in Delhi NCR?

North-facing walls receive the least solar heat, and the BEE's Eco-Niwas Samhita gives north the lowest orientation factor (0.550) for NCR's latitude. West and south-west facing glass gets hot afternoon sun in summer, so it needs shading such as a deep balcony.

How do I know if a flat has good cross-ventilation?

Look for openable windows or balcony doors on two different external walls of the main rooms, and a clear path for air through the flat. Flats exposed on only one face ventilate poorly.

How much window area should a flat have?

Eco-Niwas Samhita 2024 sets a minimum openable window-to-floor area ratio of 12.5% of carpet area for the composite climate that includes Delhi. Only the opening part of a window counts, for example about half of a two-pane sliding window.

Can the builder change the layout after I book?

Under section 14 of RERA, after disclosing sanctioned plans the promoter may make only minor changes to your flat without your consent, and needs the written consent of two-thirds of allottees for other alterations to the building plans. Structural changes and added area are not treated as minor.

Sources

Updated 20 October 2026. This article is general information, not legal or financial advice; check current rules and project details before you decide.