Indian Foundation Rules: Depth, Thickness & Concrete Grade (NBC 2016)

The requirement

Every foundation in India must go down at least 500 mm below natural ground level. That is NBC 2016 §6.2.2. Footing thickness comes off Table 4: roughly 150 mm up to 300 mm, set by footing type. Width has no set number. Concrete for a reinforced footing starts at grade M20 under mild exposure.

These rules sit in NBC 2016 Part 6, “Structural Design”. Section 2 covers soils and foundations. Section 5A covers plain and reinforced concrete. Unlike some countries, NBC sets a flat minimum depth. It does not leave depth wholly to a site test.

Depth: 500 mm, and no frost figure. NBC 2016 §6.2.2 makes every foundation reach at least 500 mm below natural ground level. The Code has no frost-line number anywhere. Frost is only named as one factor to weigh when a deeper footing is needed in fine sands or silts. That fits most of India, which has no frost-design rule at all. NBC also gives no set figure for hill or Himalayan regions. There the depth comes from a geotechnical study of your own site.

NBC 2016 Part 6 §6.2.2

1 footing
2 ground

Width: a design job, not a table lookup. NBC does not fix a strip footing’s width. The width comes from structural design. That design checks your load against the soil’s allowable bearing capacity (§7.2). Get the ground assessed for your site and load. Then size the footing to carry that load. Don’t read a width off this page.

Thickness: read Table 4 for your footing type. Table 4 (§7.3.12) sets minimum thickness by footing type and support. It runs roughly from 150 mm to 300 mm. The low end is a reinforced concrete footing resting on soil. The top end is a masonry footing, or a reinforced concrete footing resting on piles. Read the figure for your own footing type off the table. One number does not cover every case.

Concrete grade. Take a typical buried house footing under mild exposure. That is the usual case for ordinary house work. NBC 2016 Part 6, Section 5A, Table 5 sets a minimum grade of M20 for reinforced concrete. Harsher exposure pushes the grade up.

What we won’t print — rebar cover

The research behind this page found two readings of the Code on rebar cover. So we are not printing a fixed number until that is settled. Check Table 16 (Part 6, Section 5A, §25.4.2). Use the cover figure that matches your project’s exposure class. Then confirm it with the engineer who designed the rebar before you pour.

Work it out on site

The depth is fixed at 500 mm minimum. The width comes from your bearing capacity design. Once you know both, the concrete volume is just maths. It feeds straight into the calculator. Say you have a strip footing to pour. These are example numbers, not the depth or width for your job. Your real width comes off your structural design.

Total length of trench: 20 m.
Footing width: 0.6 m. Example only. Get yours from your bearing capacity design for the actual soil and load.
Footing depth: 0.5 m. That is the NBC minimum. Check whether your ground needs deeper.

Volume is length × width × depth.

20 × 0.6 × 0.5 = 6.0 m³.

So order about 6.0 cubic metres. Then add a bit for spillage and an uneven trench. Most builders tack on 5 to 10 per cent. Swap in your own numbers and the calculator does the sum.

Do it in 5 seconds

India’s building code hub. How the NBC model code gets adopted into state bye-laws.
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Sources

National Building Code of India 2016 (NBC 2016 / SP 7:2016), Bureau of Indian Standards — Part 6, Section 2 §6.2.2 and §7.2/§7.3.12 (foundation depth, width and thickness table) and Section 5A Table 5 / Table 16 (concrete grade, rebar cover). Full text is gated behind a paid BIS webstore login; check the current status at bis.gov.in.

Read this first. These figures are from NBC 2016, which BIS has withdrawn and replaced with SP 7:2026 (“National Building Construction Standards 2026”), gazette-notified in 2026 (reported 30 April 2026) and now BIS’s current national standard. NBC is also a model code: it has no legal force until your state or municipality adopts it into its own bye-laws — and every state bye-law checked for this hub still names NBC 2016, not SP 7:2026. Confirm which edition your local bye-law currently adopts, and get your ground checked with a proper site investigation, before you dig.

Frequently asked questions

What is the minimum foundation depth in India?

500 mm below natural ground level, for every foundation. That is NBC 2016 §6.2.2, a flat national minimum. The Code gives no frost-depth number anywhere. Frost is only named as one factor to weigh when going deeper in fine sands or silts. Most of India has no frost-design rule at all.

How wide does a strip footing need to be?

NBC 2016 does not fix a width. The width comes from structural design against the soil's allowable bearing capacity (§7.2). That needs a geotechnical assessment of your own site and load. It is not a table lookup.

How thick does a footing need to be?

It depends on the footing type. NBC's Table 4 (§7.3.12) gives minimums from roughly 150 mm up to 300 mm. The low end is reinforced concrete resting on soil. The top end is masonry, or reinforced concrete resting on piles. Read the exact figure for your footing type off the table.

What concrete grade does a house footing need?

M20 at minimum, for reinforced concrete. That is NBC 2016 Part 6, Section 5A, Table 5, for a typical buried house footing under mild exposure. Harsher exposure lifts the minimum grade.

What's the rebar cover for a footing?

This one is not settled, so we do not print a single number. Check NBC 2016 Part 6, Section 5A, Table 16 for the cover that matches your exposure class. Then confirm it against the specific footing clause with your engineer before you pour.