The CODE Construction. Design. Engineering. India's No.1 Construction Podcast

The final part of our listener Q&A series. You sent your questions to my DMs — here are the last 25 answers, with the science, the logic and the IS code behind each one.

On this episode of The CODE – India's No.1 Construction Podcast, Rishabh Aggarwal covers steel cover and checks, bricks and blocks, sand and water, mortar and plaster, foundations and site work, and how much material a house really needs.

Questions answered in this episode:

21. Minimum steel in columns, beams and slabs

22. How much concrete cover steel needs

23. How to check TMT bars on site

24. Red brick, fly ash, concrete block or AAC?

25. Standard brick size in India

26. How to tell a good brick from a bad one

27. Should bricks be soaked before laying?

28. What's the white powder on your walls?

29. Which wall keeps your house cooler?

30. River sand or M-sand?

31. What sand "zones" mean

32. The simple silt test for sand

33. Can you use sea sand or seawater?

34. Which size of aggregate to use

35. What water is safe for concrete

36. Mortar ratio for brickwork

37. Plaster ratio and thickness

38. Why plaster cracks, and how long to cure it

39. Do you need a soil test?

40. Removing topsoil before a footing or slab

41. Anti-termite treatment — when and how

42. What a damp-proof course does

43. Cement, steel and bricks for a 1,000 sq ft house

44. Getting an accurate BOQ and allowing for wastage

45. Why material prices vary so much

New here? Start with Part 1 (EP 169) and Part 2 (EP 170).

This is general guidance. Structural decisions should always come from a licensed structural engineer.

What should the next Q&A series cover? Send your ideas to Rishabh on Instagram.

If this series helped you, follow The CODE and leave a rating — it helps more builders, architects and homeowners find the show.

🎙️ The CODE – India's No.1 Construction Podcast

Hosted by Rishabh Aggarwal

📺 Watch on YouTube: @indiasno1constructionpodcast

Part 2 of our listener Q&A series. You sent your questions to my DMs — here are the answers, with the science, the logic and the IS code behind each one.

On this episode of The CODE – India's No.1 Construction Podcast, Rishabh Aggarwal answers the next 12 questions: the rest of your concrete questions, everything on TMT steel, and how to choose bricks or blocks for your home.

Questions answered in this episode:

00:00 Intro

00:29 Q11: How many days should concrete be cured?

01:35 Q12: When should shuttering be removed?

02:52 Q13: Can you pour concrete in extreme heat or cold?

04:10 Q14: Does concrete harden underwater?

04:45 Q15: 7-day concrete strength and cube testing

05:52 Q16: Grade and cement content for durability

06:58 Q17: Fe415, Fe500, Fe500D or Fe550D — which steel to buy?

09:15 Q18: What is TMT, and why is it better than twisted bars?

10:46 Q19: Can rusted steel be used on site?

12:03 Q20: Why do rings need 135° hooks?

New here? Start with Part 1 (EP 169) on cement, concrete and shuttering.

This is general guidance. Structural decisions should always come from a licensed structural engineer.

Have a question for Part 3? Send it to Rishabh on Instagram.

If this episode helped you, follow The CODE and leave a rating — it helps more builders, architects and homeowners find the show.

🎙️ The CODE – India's No.1 Construction Podcast

Hosted by Rishabh Aggarwal

📺 Watch on YouTube: @indiasno1constructionpodcast

You sent your questions to my DMs. In this episode, I answer them — with the science, the logic and the IS code behind every answer.

This is Part 1 of our listener Q&A series on The CODE – India's No.1 Construction Podcast. Rishabh Aggarwal takes on the first 12 questions, all about cement, concrete and shuttering: what to do on site, why it works, and which Indian Standard says so.

Questions answered in this episode:

1. What's the real difference between cement and concrete?

2. 33, 43 or 53 grade — which cement should you use for your home?

3. OPC, PPC or PSC — which is better?

4. Why does cement have a 30-minute minimum setting time?

5. Does cement expire, and how should you store it?

6. How do you check a cement bag on site?

7. What do M15, M20 and M25 mean, and what mix ratio should you use?

8. What happens when you add extra water to concrete?

9. What slump should your concrete have?

10. Why does concrete crack?

11. How many days should you cure concrete?

12. When should shuttering be removed?

This is general guidance. Structural decisions should always come from a licensed structural engineer.

Have a question for Part 2? Send it to Rishabh on Instagram.

If this episode helped you, follow The CODE and leave a rating — it helps more builders, architects and homeowners find the show.

🎙️ The CODE – India's No.1 Construction Podcast

Hosted by Rishabh Aggarwal

📺 Watch on YouTube: @indiasno1constructionpodcast

Delhi-NCR floods every single monsoon — and every year, it's treated like a surprise. In this episode, we go street by street and drain by drain to find out why: a British-era sewer still running under Minto Bridge, a drainage master plan from 1976 that wasn't replaced until 2025, and a written warning about a collapsed sewer in Noida that went unanswered for four years — until someone died.

This one's for anyone who's ever waded through a flooded street in Delhi, Gurugram, or Noida and wondered whether it actually has to be this way.

We cover: the scale of the 2025–2026 flooding, why the city's underground infrastructure hasn't kept pace with its population, what happens when accountability systems exist on paper but not in practice, and how Tokyo, Copenhagen, Kuala Lumpur, and Shenzhen faced the exact same crisis and solved it. We also look at Bengaluru's K-100 drain — twelve kilometres of proof that this is fixable, even here.

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A building collapsed in Satya Niketan, South Delhi, on September 6, 2026. At least six people didn't come home — most of them students. The building was around 55 years old, mid-renovation, with water reportedly pooling in its basement during repair work.

In this episode, we trace that collapse back through a century of policy that made it possible.

We go back to 1908, when a colonial-era red line called the "Lal Dora" first exempted Delhi's villages from building rules — an exemption independent India inherited and never fully closed. We look at the Delhi Development Authority's own admitted housing shortfall — nearly 4 lakh homes short of its targets, a population undercounted by over a million in its very first master plan. We examine Saidulajab, where Delhi Police formally flagged illegal construction to MCD twice, two months before six people died there in May 2026. And we go clause by clause through the newly notified Master Plan of Delhi 2047 — an 800-page document that admits Delhi's structural safety gaps in its own printed text, while its financial architecture leans heavily toward private developers over citizen-led redevelopment.

This isn't an episode about blame. It's a roadmap — what the government needs to do differently, what agencies need to change, and what citizens can realistically demand and act on, starting today.

Every claim in this episode is sourced and fact-checked. Full source list and gazette clause citations are in the show notes.

This is The CODE. Episode 167.

Show notes / sources:
Al Jazeera, ABC News, Reuters (Satya Niketan collapse, Sept 2026) · Outlook India (Saidulajab collapse, MCD warnings, Sept 2026) · Deccan Herald, The Tribune (Welcome/Seelampur collapse, July 2025) · The Print, Millennium Post (Karawal Nagar, June 2026) · Master Plan of Delhi 2047, Gazette of India, August 2026 · Delhi Development Act, 1957 · Kamal Nath, DDA workshop remarks, 2010 · Manohar Lal, Ministry of Housing and Urban Affairs, April 2026 · Central Bureau of Investigation press releases, 2026 · Supreme Court of India, Bar and Bench, Feb 2025

A free, no-fluff masterclass on Ultra-High Performance Concrete — the material up to 16x stronger than normal concrete, and the questions the industry doesn't like answering out loud.

Dr. Satish Jain, Managing Director of UHPC India Pvt. Ltd. and PhD (Iowa State University), joins us for EP 166. His doctoral research on UHPC in post-tensioned floor systems led to a US patent for a new UHPC anchoring system — including early tests that failed before he found what actually worked.

We go from "what even is UHPC?" to the real cost math, the carbon question nobody in the industry wants to answer honestly, and whether India built its UHPC push on solid engineering — or on government momentum.

What we cover:

- What UHPC actually is, and how it differs from UHPFRC

- The world's first UHPC bridge — built in 1997, still standing

- Inside UHPC India: from a 2019 startup to Chennai Metro's radar

- Did India rush into UHPC because of government push, or did it earn its place?

- The real recipe — no gravel, near-zero water — and why it works

- Dr. Jain's own patent: the test that failed, and what it taught him

- The real cost: is UHPC 4x, 10x, or 15x the price of normal concrete?

- Is "Ultra Green" concrete actually green?

- Will UHPC fail in India before its own building code even exists?

- Should a young engineer bet their career on this material?

Timestamps:

00:00 Cold open

00:30 What actually IS UHPC?

04:00 UHPC vs UHPFRC, and the world's first UHPC bridge (1997)

08:00 Inside UHPC India: from 2019 startup to CMRL's radar

13:00 Did India rush into UHPC because of government push?

17:00 The real recipe: why removing gravel makes it stronger

24:00 Dr. Jain's own patent: the test that failed

30:00 The real cost: 4x? 10x? 15x? We do the math

36:00 Is "Ultra Green" concrete actually green?

42:00 Will UHPC fail in India before its code even exists?

48:00 Closing: should you bet your career on this material?

Learn more about UHPC India: https://uhpcindia.com

Follow the show for more deep dives into the materials and engineering shaping India's infrastructure.

A construction firm in India engineered a supertall commercial tower in AI-optimised steel. 17% less steel than a traditional design. 1,000 tonnes saved. Cost parity with RCC — which flips the assumption every Indian developer starts with.

The design was never built.

Not because the numbers didn't work. Because in 2026, India's construction ecosystem — codes, approvals, market risk appetite — couldn't accommodate it.

Rahul Bahl is the third-generation Managing Director of Krishna Buildestates — ₹850 Cr revenue, ₹3,000 Cr+ order book. He's just delivered a 191-metre RCC tower in NCR, the tallest KBE has ever built. And his firm is the one that engineered the AI-optimised steel supertall the ecosystem said no to.

00:00 Cold open — the design that wasn't built

05:09 Whose failure is India's missing supertall

07:19 Why NCR can't do supertalls — seismic Zone 4

11:30 Can Indian buyers trust a steel-frame tower

17:12 Why supertall projects in India run long

20:17 The general contractor model

26:32 The code wall — E450 steel and what got rejected

29:35 LERA and Merdeka 118 — codes as a reference, not a ceiling

43:37 What AI-optimised structural design actually means

46:55 The numbers — 17%, 1,000 tonnes, cost parity with RCC

55:59 The rejected design — what actually broke it

1:09:40 Prescription — developers, BIS, young engineers

In this episode:

— Why NCR's seismic Zone 4 makes supertall economics fundamentally different from Mumbai's
— Why the Indian buyer doesn't yet trust a steel-frame residential tower, and whether that's fair
— The LERA philosophy from the engineers behind Merdeka 118: codes are a reference, not a ceiling
— What AI-optimised structural design actually means — the engineering version, not the marketing one
— Where cost parity with RCC really comes from, and the one assumption that would break it
— Whether India has a shadow inventory of good supertall designs no one has ever heard of
— The specific rejected design that anchors this whole conversation

Empire State Building: 410 days in 1931. Merdeka 118: 679 metres, finished 2023. India, the world's fifth-largest economy, is still not on that board. At the end of the episode, Rahul gives a number — the years he thinks it will take India to deliver its own supertall, if the ecosystem gets its act together. Stay for that.

The CODE is a podcast about the business, engineering, and politics of how India gets built. Hosted by Rishabh Aggarwal. New episodes weekly.

Follow The CODE on Instagram and LinkedIn. Watch the full video on YouTube.

There's a concrete dome in Rome that has stood for 1,900 years —

unreinforced, open to the rain, still perfect. Meanwhile, the concrete

we pour today has an expiration date of 50 years. We had the secret.

We threw it away. This is the story of why.

In this solo episode, Rishabh Aggarwal unpacks one of the strangest

trades humanity ever made: we swapped a material that could outlive

empires for one that builds skyscrapers but rusts itself to death from

the inside out.

You'll learn:

- How the Romans built self-healing concrete 2,000 years before MIT

figured out how it worked

- Why "Portland Cement" was named after a marketing lie — and why its

real inventor was a con artist who threw fake magic crystals into

his kilns

- What "concrete cancer" actually is, and why the steel rebar inside

every modern building is a time bomb from day one

- Why rust swells 4 to 5 times its original size and destroys

structures from within

- The uncomfortable truth: was modern concrete's short life an

accident of chemistry, or a business decision?

- Bio-concrete, basalt rebar, and the volcanic ash comeback — how

we're trying to reinvent Roman concrete with superpowers

This one is for civil engineers, architects, contractors, construction

students, and anyone who has ever walked past a construction site and

wondered what we're actually building.

The CODE is India's No.1 Construction Podcast, hosted by Rishabh Aggarwal.

Follow the show for weekly episodes on construction, materials,

architecture, and the future of how we build.

Instagram: @indiasno1constructionpodcast

YouTube: @indiasno1constructionpodcast

A ₹5 crore home became a ₹9 crore home — an 80% overrun. Where did the extra ₹4 crore come from? From under the ground.

Soil is the one thing nobody checks, nobody tests — and it quietly becomes the most expensive mistake in your entire build. In this solo episode, I break down everything your contractor probably won't tell you about soil and foundation, and why a ₹20,000 test can save you crores.

In this episode:

- SBC (Safe Bearing Capacity) — the one number that decides how much load your soil can safely carry

- Black Cotton Soil — the "hidden killer" under nearly a quarter of India that swells, lifts, and cracks homes season after season

- Why "it was fine on my neighbour's plot" is dangerous logic

- What actually happens in a soil test — boreholes, SPT, lab tests, and the plate load test

- How the water table can cut your soil's bearing capacity by 30-60%

- Seismic zones — which one your plot sits in and why it changes your foundation

- The most important takeaway: do this test BEFORE you buy the plot, not after

If you're building a home or hunting for a plot, this one could save you crores. Share it with someone who needs to hear it before they buy.

Referenced codes: IS 1892:1979, IS 1904:2021, IS 6403, IS 2131, IS 1893:2016, NBC SP-7:2005.

THE CODE — India's No. 1 Construction Podcast. There's a code behind every home. We break it down so you save money and build it right.

Next episode: the most troublesome room in every home — the bathroom.

Follow the show and leave a rating if this helped you.

Ramesh ji spent ₹1.8 crore on a brand-new Bangalore apartment. East-facing. Park view. His dream home. First night in — he couldn't sleep. Neighbour's TV through the wall. Footsteps from upstairs. Water pressure in the pipes. By 3 AM, he was playing sleep meditation on YouTube in his own bedroom.

His problem wasn't the mattress. It wasn't the curtains. His home was simply never built to be acoustically livable — and that's the story of almost every Indian home today.

In Episode 162 of The CODE, we go deep into the engineering of silence. You'll learn the two numbers every homeowner should know — STC (Sound Transmission Class) and NRC (Noise Reduction Coefficient) — and why India's average construction delivers roughly half the international residential standard. We unpack the 100-year-old Sabine Formula, walk through NBC 2016 Part 8 (India's official acoustic building code that almost no one references), and break down 10 specific, science-backed ways to soundproof your home.

We cover AAC blocks vs traditional red bricks, decoupled wall construction, floating floor systems that kill 15-25 dB of impact noise, why your door is the single weakest point in any room, double glazed window hacks, rockwool insulation, drop ceilings with isolation clips, acoustic treatment inside the room, and the free architectural planning move that can save you lakhs in retrofit costs later.

Plus a myth-buster you won't hear anywhere else: the truth about Rat Trap Bond walls. Brilliant for thermal efficiency and cost savings — but acoustically, the physics tells a very different story than what sustainable construction influencers are claiming.

Whether you're planning your dream home, mid-construction, or stuck in an apartment where you can hear every footstep upstairs, this episode gives you the engineering vocabulary and the specific interventions to fix it.

Because a home that can't give you sleep isn't a home. It's just a building.

Topics: soundproofing, acoustic design, STC, NRC, NBC 2016, IS 8225, AAC blocks, floating floors, Rat Trap Bond, Indian home construction, architecture, building science, sleep health.

The CODE — India's No. 1 Construction Podcast. New episodes every week. Send this to your architect and contractor before your next project meeting.