Life of RCC Building: Design Life, Real Lifespan and Depreciation by Age

What is the life of an RCC building as per IS code?

No Indian code puts a single “life in years” stamp on an RCC building. The nearest thing is Table 1 of IS 875 (Part 3):2015, which links the life a structure is designed for to how strong a wind it must resist. An ordinary house, flat, school or office falls in the first row: 50 years.

Table 1: Mean probable design life by class of structure (IS 875 Part 3:2015, Table 1, clause 6.3.1)

The risk factor k₁ multiplies the basic wind speed of the zone. A building meant to stand longer is more likely to meet a rare, violent storm, so it is designed for a higher wind. That is why a hospital gets a factor above 1.0 and a site shed gets one well below it. The note under the table says the factor is based on “period of time in years during which these will be exposed to wind, that is, life of the structure”.

IS 456:2000, the main Indian code for plain and reinforced concrete, gives no number of years at all. It talks about the “service life” and “working life” of concrete and controls them through durability rules in clause 8: the exposure class, the cement content, the water-cement ratio, the grade of concrete and the cover to the steel. Clause 8.2.1 says it plainly: “The life of the structure can be lengthened by providing extra cover to steel, by chamfering the corners or by using circular cross-sections or by using surface coatings.”

So the honest answer to “life of RCC building as per IS code” is this: 50 years is the design basis for general buildings, and IS 456 sets the material rules meant to make the concrete last that long.

Design life, service life and economic life: what is the difference?

Three different numbers get called “the life of a building”, and mixing them up causes most of the confusion on this topic.

Table 2: The three kinds of building life

A building can pass its design life and still be sound. Another can be well inside its design life and already be unsafe. Only the service life is a fact about the actual building, and it can only be judged by looking at it.

How long does an RCC building last in India?

It depends mostly on two things: how harsh the surroundings are and how well the concrete was made. IS 456 sorts the surroundings into five exposure classes and asks for stronger, denser concrete and thicker cover as the class gets worse. Cover is the layer of concrete between the outer face and the steel bar. It is the steel’s only shield.

Table 3: Exposure class and the minimum concrete for RCC (IS 456:2000, Tables 3, 5 and 16)

The cement and water-cement values in Table 5 are for 20 mm aggregate. A few more cover rules sit in clause 26.4: footings need at least 50 mm, the main bars of a column need at least 40 mm, and the cover on site may be up to 10 mm more than the drawing but never less.

Read the table the other way and it explains why two houses built in the same year age so differently. A house in a dry inland town, built to the code with the right cover, ages slowly. The same design near the sea, or built with thin cover and a wet mix, can show rusted bars much sooner. The water-cement ratio guide explains why extra water makes concrete weaker and more porous. The cover blocks guide explains how the cover is held in place while the concrete is poured.

Good concrete starts with good mixing. On a house or small building, a self-loading mixer such as the AJAX ARGO 4500 weighs and mixes the batch at site; compare the full range of concrete mixers before the slab pour.

What shortens the life of an RCC building?

Almost every RCC building that dies young dies the same way: the steel rusts, the rust swells, and the swelling cracks the concrete off the bar. The causes below all lead to that end.

Figure 1: How carbonation moves through the cover towards the steel

Carbonation comes first, because it happens to every building. Carbon dioxide from the air slowly reacts with the lime in hardened concrete. The pore water inside fresh concrete has a pH of about 12.5 to 13.5, which keeps the steel protected. Carbonation brings it down towards 8.5, and below about 9.5 to 10 the steel loses that protection and can rust. Thin cover and porous concrete let the carbonated layer reach the bar sooner.

Salt is faster and more dangerous. Chlorides cause pitting rust that eats into a bar at points, and they come from sea air, sea sand, salty mixing water and some quick-setting additives. IS 456 Table 7 caps the total acid-soluble chloride in reinforced concrete at 0.6 kg per m³ of concrete, and at 0.4 kg per m³ for prestressed concrete.

Water does the rest. A roof, toilet or water tank that leaks for years keeps the concrete wet, and wet concrete with oxygen is where rust grows fastest. Rising damp from the ground does the same to the lower walls; the damp proof course guide and the waterproofing chemicals guide cover the fixes.

Site mistakes made on the day of the pour shorten life too:

• Concrete that is not vibrated properly leaves stone pockets and voids that let water straight in to the steel. See the honeycombing guide.
• Concrete left to dry out in the first days never reaches its full strength and stays porous at the surface, which is exactly the cover layer. The curing compound guide explains the options.
• Cover blocks that slip or are left out put the bar right under the surface.

Later changes can do the same damage. An extra floor, a water tank moved onto a slab or a shop turned into a godown loads beams and columns beyond the design. Never add a floor without a structural engineer checking the existing frame.
Rust is the reason all of this matters so much. Iron rust takes up about six to seven times the volume of the steel it came from. That swelling pushes the cover off the bar, the bar is then exposed, and it rusts faster still.

How do valuers depreciate a building by age?

When a valuer works out what an existing building is worth, the usual method is straight-line depreciation: the building loses the same share of its value every year of an assumed total life, down to a scrap value at the end. Only the structure is depreciated. The land is valued separately.

The arithmetic is simple:

Depreciated value = replacement cost × [1 − (1 − s) × A ÷ L]

Here A is the age of the building in years, L is the total life the valuer assumes, and s is the scrap (salvage) value as a share of the cost. Replacement cost is what it would cost to build the same structure new today. Where the valuer judges the remaining life R from the building’s condition, the total life is simply L = A + R.

Table 4: Worked example, value left by age, assuming L = 60 years and s = 10% (our own arithmetic)

Change the assumption and the answer changes a lot. The same 20-year-old building, with a total life of 75 years instead of 60, loses 0.9 × 20 ÷ 75 = 24% and keeps 76% of its replacement cost, not 70%. So when you read a valuation report, look first for the total life and the scrap value it assumed, and check that they suit the building’s real condition. A report that gives a 30-year-old building with rusting columns the same remaining life as a sound one has not looked at it.

Tax depreciation and company-accounts depreciation are a different subject. They follow rates and lives set in law, those rules change, and your chartered accountant applies them. This section is about valuing the building itself.

How do you check whether an old RCC building is near the end of its life?

Age alone tells you little. These signs tell you much more, and most can be seen in a walk around the building:

• Brown rust stains on plaster or concrete, especially under slabs, on balcony edges and around toilets.
• Cracks that run straight along the line of a bar in a beam, column or slab, rather than random hairline cracks in plaster.
• Pieces of concrete falling off to show bare, rusted bars. This is called spalling.
• A slab or beam that sags, or doors and windows that start to jam.
• Cracks in columns, and damp patches that never dry out even in summer.

If you see these, call a structural engineer. The usual site tests are a cover meter to measure how deep the bars are, a phenolphthalein spray on a freshly broken surface (it turns pink where the concrete is still alkaline and stays colourless where it has carbonated), a rebound hammer and ultrasonic pulse velocity test to judge the quality of the concrete, core samples for strength, and half-cell potential readings to map where the steel is likely to be rusting. Together they show whether the building needs local repair, major strengthening or replacement.

Can the life of an RCC building be extended?

Yes, if the damage is caught early. The order of work matters:

1. Stop the water first. Fix roof, toilet, tank and pipe leaks before anything else, or every repair below fails again.
2. Repair spalled areas properly: cut back the loose concrete, clean the rust off the bars, add steel where the bar has lost section, coat the bars and rebuild the cover with a repair mortar or non-shrink grout.
3. Seal cracks and keep the plaster and exterior paint in good order. They slow down carbonation and keep rain out of the cover.
4. Let a structural engineer decide on strengthening, such as jacketing a weak column, where tests show the concrete or steel has lost strength.

Sometimes repair costs more than it saves, and the building comes down. On a small single-storey house, much of the work can be done with a backhoe loader such as the JCB 3DX. A multi-storey RCC frame usually needs a crawler excavator such as the Tata Hitachi EX 210 Infra fitted with a hydraulic rock breaker to break the slabs and columns. What demolition costs is covered in our demolition cost guide, and what to do with the debris in the construction and demolition waste rules.

Figure 2: An excavator taking down an old building once repair no longer pays

Planning the new building? Start with the house construction cost calculator, read PCC vs RCC to see where each concrete goes, and browse the concrete mixers for the pours. More estimating topics are in the construction cost guides.

The design life classes and k₁ factors on this page are from IS 875 (Part 3):2015, Design Loads (Other than Earthquake) for Buildings and Structures, Wind Loads, Table 1 and its note. The durability rules, exposure classes, mix limits, cover and chloride limits are from IS 456:2000, Plain and Reinforced Concrete, Code of Practice, clauses 8.1, 8.2.1, 8.2.2.1 and 26.4 and Tables 3, 5, 7 and 16. The pH and rust-volume figures are from the Wikipedia article “Concrete degradation”. The depreciation table is our own arithmetic on stated assumptions, not a rule from any code. All sources were read in November 2026.

Prices, specifications and features are indicative, vary by variant, location and date, and should always be confirmed with the official OEM or authorised dealer before any purchase decision. DesiMachines is not liable for decisions taken on the basis of information that may have changed after publication. The condition and safety of a particular building can only be judged by a qualified structural engineer after inspection; this page explains the code basis and general practice and does not replace that assessment.