What can you build on a 20×40 ft plot in Chennai?
A 20×40 ft plot is 800 ft² (74 m²) — about 1.8 cents. Under the Tamil Nadu Combined Development and Building Rules, 2019 (non-high-rise residential), it carries an FSI of 2 and a 12 m height cap; the setbacks — and so your buildable footprint — depend on the width of the road the plot faces.
Buildable area by road width
Assuming the 20 ft side faces the road (side and rear setbacks 1.5 m each; front setback varies):
| Road width | Front setback | Buildable footprint | Per floor | Max total built-up (FSI 2) |
|---|---|---|---|---|
| Under 30 ft (under 9 m) | 1.5 m (4.9 ft) | ~10.2×30.2 ft | ~306 ft² | 1,600 ft² |
| 30–59 ft (9–18 m) | 3 m (9.8 ft) | ~10.2×25.2 ft | ~256 ft² | 1,600 ft² |
| 60–100 ft (18–30.5 m) | 4.5 m (14.8 ft) | ~10.2×20.3 ft | ~206 ft² | 1,600 ft² |
| Over 100 ft (30.5 m+) | 6 m (19.7 ft) | ~10.2×15.4 ft | ~156 ft² | 1,600 ft² |
Footprints are the rectangle left after setbacks; the FSI cap applies to the whole building across floors. Corner plots, wider frontages and layout conditions change these numbers — the generator computes them for your exact facing and road.
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Plot2Plan turns these limits into an actual room-by-room floor plan: the rule engine freezes the legal envelope, AI arranges the rooms inside it, and a validator checks every wall, door and stair before you see it.
Frequently asked questions
How many floors can I build on a 20×40 plot in Chennai?
The height cap is 12 m (about four floors at 3 m each), and FSI 2.0 limits total built-up area to 1,600 ft². On a 30 ft road: Here the height cap binds first: 4 full-footprint floors of ~256 ft² give about 1,024 ft², still inside the FSI cap.
What is the setback for a 20×40 plot in Chennai?
Side and rear setbacks are 1.5 m each. The front setback depends on the road: 1.5 m on roads under 9 m, 3 m on 9–18 m roads, 4.5 m on 18–30.5 m roads and 6 m on roads over 30.5 m (TNCDBR 2019, Rule 35(1)(a)).
How much construction is allowed on a 20×40 plot in Chennai?
At FSI 2.0, a 800 ft² plot allows up to 1,600 ft² of total built-up area across all floors, subject to setbacks and the 12 m height limit.
This size by facing
Vastu placement, entrance position and sun differ by facing — each gets its own guide:
Other plot sizes
- 20×30 ft plot
- 24×36 ft plot
- 25×40 ft plot
- 30×40 ft plot
- 30×50 ft plot
- 30×60 ft plot
- 40×40 ft plot
- 40×60 ft plot
- 50×80 ft plot
New to the rules? Start with the Chennai setback rules guide.