- Is a cool roof compulsory in Hyderabad?
- What the policy is actually buying
- The second rule nobody mentions: the national envelope code
- Why the west wall costs you more than the roof
- What actually reduces heat, in the order it should be decided
- Insulation and reflectivity are not the same thing
- What that code is worth at national scale
- How this goes wrong on real sites
- What to ask for in writing
- How we handle this at Simfy Homes
- When we are not the right fit
- Frequently asked questions
Two separate rules decide how a Hyderabad house handles heat, and both switch on at almost exactly the same plot size. Most owners building at that size have never been told about either one.
One is a state policy about what colour your terrace is. The other is a national code about how much heat your walls and windows are allowed to let through. They were written by different bodies for different reasons, and neither is explained by the person quoting you for a roof.
The overlap is not a coincidence anyone planned, but it is useful. If your plot is around 600 sq yd or larger, you are inside both. This guide sets out what each one asks for, what the measured numbers actually look like in this city, and which decisions make the difference long before anyone reaches for a tin of paint. It sits alongside our note on sustainable home construction in Hyderabad.
Is a cool roof compulsory in Hyderabad?
On bigger plots, yes. And you will not get your occupancy certificate without it. Telangana Today reports that the Telangana Cool Roof Policy took effect on 1 April 2023 and is mandatory for all government buildings, for non-residential and commercial buildings regardless of area, and for residential buildings on plots of 600 square yards and above.
Below that size it is voluntary. Above it, the same report states that occupancy certificates are issued only after compliance with the policy is confirmed. That is the part owners react to. A reflective terrace is not a green gesture at that plot size — it sits on the path between a finished house and a legal one.
Telangana Today puts the cost at roughly ₹300 a square metre, recovered in about two years through lower cooling load. For a 250 sq m terrace that is about ₹75,000 of material and labour on a house that will cost many multiples of it. Nobody argues about the money. The arguments happen when it is discovered at the end.
What the policy is actually buying
Surface temperature. A reflective terrace sends most of the sun’s energy back out instead of storing it in the slab and releasing it into the rooms below through the evening.
The measured version is more persuasive than the theory. The Aga Khan Agency records testing by IIIT-Hyderabad at Garden Housing Society in the city, where terrace surface temperatures fell by 15 to 20 degrees after reflective and china mosaic treatment, and peak indoor temperatures fell by 3 to 4 degrees. That was across a ten-acre society of more than fifteen mid-rise buildings.
Three to four degrees is the number worth sitting with. It is the difference between an air conditioner running through the night and one that cycles off. On a large home with several machines, that is not a rounding error on the bill.
The state’s ambition is on the same scale. Telangana Today gives the target as 200 sq km of treated roof in Hyderabad and 100 sq km in the rest of Telangana by 2028-29, starting from 5 and 2.5 sq km in the first year.
The second rule nobody mentions: the national envelope code
Eco Niwas Samhita is the national energy code for homes, and clause 2.2.1 applies it to residential buildings built on a plot area of 500 sq m or more. Six hundred square yards is about 502 sq m.
So the two rules land within a few square metres of each other. If the cool roof policy applies to your plot, the national envelope code almost certainly does too — and while the roof gets talked about because it is visible, the code is about the whole envelope.
Two numbers carry most of it. Eco Niwas Samhita sets a maximum RETV of 12 watts per square metre for composite, hot-dry, warm-humid and temperate climate zones, and a maximum roof thermal transmittance of 1.2 W/m²K. Hyderabad sits in the composite zone. The earlier 2018 edition allowed 15 W/m²; the 2021 edition tightened it.
RETV is a single figure for how much heat the walls and windows of your house let in across a year, given their areas, orientations, shading and glass. It is the honest measure, because it refuses to let a good wall excuse a bad window. Two houses with identical walls can sit either side of the limit purely on where the glass is.
| Rule | Applies from | What it limits |
|---|---|---|
| Telangana Cool Roof Policy | Residential plots of 600 sq yd and above | Roof surface reflectivity |
| Eco Niwas Samhita, clause 2.2.1 | Plot area of 500 sq m and above | Whole envelope: RETV and roof U-value |
Why the west wall costs you more than the roof
The roof takes the most sun in a day. The west wall takes its share in the four hours when the house is already hot and the family is coming home.
A terrace gains heat from mid-morning and radiates it down through the evening, which is why the policy targets it. But an unshaded west wall with glass in it delivers heat at exactly the hour when nobody wants it, and no paint fixes that. It is a plan problem, decided when the rooms are arranged.
In Hyderabad the practical ordering of west-facing rooms is settled at drawing stage. Stairs, stores, bathrooms and utility spaces on the west face absorb the afternoon load and cost nothing extra. Bedrooms and living spaces on that face need deep shading, smaller openings, or they need to move. Once the walls are up, the only remaining tools are curtains and electricity.
What actually reduces heat, in the order it should be decided
- Orientation and room placement. Free at drawing stage. Impossible afterwards. The single biggest lever anyone has.
- Window size and position by face. North glass is generous light with little heat. West glass is the opposite. RETV is decided here more than anywhere.
- External shading. A projection that stops sun reaching the glass beats any glass that tries to stop it after it has arrived.
- Roof insulation. The 1.2 W/m²K roof limit is met with an insulating layer in the terrace build-up, not with a coat of paint.
- Reflective terrace finish. The coating itself. Cheap, effective, mandatory on the larger plots, and the last of the five, not the first.
- Cross ventilation. Openings on two faces of a room so night air can actually move through and flush the slab heat out.
The ordering matters because money spent at the top of this list is worth several times the same money spent at the bottom. An owner who arranges the plan around the sun and then paints the terrace has a cool house. An owner who paints the terrace of a house with three west-facing bedrooms has a slightly less hot one.
Insulation and reflectivity are not the same thing
Reflectivity keeps heat from entering the slab. Insulation slows whatever does enter from coming through. A terrace needs both, and they sit in different layers.
This is the confusion we correct most often. A white terrace with no insulation still heats up, more slowly; an insulated terrace in dark grey stone still absorbs, then holds. The roof transmittance limit in the code is an insulation number, and a reflective finish alone will not meet it.
In practice the terrace build-up carries a screed to falls, waterproofing, an insulation layer, protective screed and the finish. Where that insulation sits relative to the waterproofing is a detail that decides whether the roof lasts, and it is drawn, not improvised. The same discipline applies to the layers in a rainwater harvesting pit — once it is covered, nobody can check what went in.
What that code is worth at national scale
The Press Information Bureau states that implementing the residential code has the potential to save 125 billion units of electricity a year by 2030, equivalent to about 100 million tonnes of carbon dioxide.
That figure is not an argument for your house. It is context for why a code that used to be advisory keeps getting tighter, and why the plot-size thresholds keep coming down. Building to today’s minimum on a house meant to last forty years is a choice about which decade you want it to feel comfortable in.
Orientation, shading and the terrace build-up are free to decide on paper and expensive to fix in concrete.
How this goes wrong on real sites
- Discovered at occupancy stage. The terrace is finished in dark stone, the certificate is held, and the fix is now a retrofit over a completed waterproofing layer.
- Paint treated as compliance. A reflective coat applied over an uninsulated slab, meeting the visible rule and missing the transmittance one.
- Coating over a damp terrace. Applied before the slab has dried out, it lifts within a season and the owner concludes the coatings do not work.
- Glass chosen by the elevation. Large west openings put in for the look, then fought with heavy curtains and an extra tonne of cooling for the life of the house.
- No shading drawn. Projections left to the site instead of the drawing, so they end up too shallow to shade anything at three in the afternoon.
- Insulation value taken on trust. A board specified by brand with no thickness or conductivity figure anywhere in the contract, so anything can arrive.
What to ask for in writing
Ask for four things, and ask for them before the terrace is laid rather than after.
A terrace build-up drawing showing every layer in order, with the insulation thickness and its conductivity stated. The reflectance figure for the finish you are being sold, on paper from the manufacturer. The RETV working for your design, since it is a calculation somebody has to do rather than an opinion. And photographs of the insulation and waterproofing in place before the protective screed covers them.
The same principle runs through everything that gets buried. Our note on checking construction quality covers the wider version: the layers you cannot inspect later are the ones to photograph now.
How we handle this at Simfy Homes
Sun path comes before elevation. We settle which rooms face west, how deep the projections are and how large the openings can be while the plan is still on paper, because that is where the heat decision is genuinely free. The terrace build-up is drawn as a layered detail with the insulation named and dimensioned, and the reflective finish is specified with its reflectance value rather than its colour.
On plots at or above the thresholds we treat both rules as design inputs from the first drawing, not as a compliance scramble before the occupancy certificate. If you are planning a home in Hyderabad and the plot is anywhere near that size, talk to our team before the elevation is frozen.
When we are not the right fit
If the house is already built and the question is which coating to buy for the terrace, you do not need us. A good applicator with a manufacturer-backed product will do that job properly and quickly, and we would only be adding a layer of cost to a straightforward purchase. Where we earn our place is on homes still at drawing stage, where the plan itself can be made to do most of the work before anything is bought at all.
Frequently asked questions
Is a reflective terrace mandatory for my house in Hyderabad?
If the plot is 600 sq yd or more, yes. Telangana Today reports that the policy has been mandatory for residential buildings at and above that plot size since 1 April 2023, and that occupancy certificates are issued only after compliance is confirmed. Below that size it is voluntary.
What does the treatment cost?
Telangana Today puts it at about ₹300 a square metre, with the outlay recovered in roughly two years through reduced cooling. On a typical large terrace that is a small line item, and it is far cheaper applied to a fresh terrace than retrofitted to a finished one.
How much cooler does it actually make the house?
The Aga Khan Agency records testing by IIIT-Hyderabad at a Hyderabad housing society where peak indoor temperatures fell by 3 to 4 degrees and terrace surface temperatures by 15 to 20 degrees. Indoor benefit depends on what is under the roof, so the top floor gains most.
Does white paint on the terrace meet the rules?
It addresses the reflectivity rule and not the insulation one. The code sets a maximum roof thermal transmittance of 1.2 W/m²K, which is met by an insulating layer in the terrace build-up. Reflectivity and insulation do different jobs in different layers.
What is RETV and why does it matter to me?
It is a single number for how much heat your walls and windows let in over a year. The code sets a maximum RETV of 12 W/m² for composite, hot-dry, warm-humid and temperate zones. It matters because it is decided by your plan, and a plan is cheap to change and expensive to regret.
Does the national code apply to my plot?
Clause 2.2.1 of the national code applies it to residential buildings on a plot area of 500 sq m and above. Six hundred square yards is roughly 502 sq m, so a plot inside the cool roof mandate is almost always inside the envelope code as well.
Which is worse in Hyderabad, a hot roof or a west wall?
The roof collects more over a day, the west wall delivers more in the evening. The roof is the easier fix because it can be treated late. The west wall is decided when the rooms are placed, so it is the one to settle first even though it gets discussed last.
Can I add insulation to a terrace that is already finished?
Yes, but it means lifting the finish and often redoing the waterproofing beneath it, so the work costs several times what the same insulation would have cost in the original build-up. Coating is the practical retrofit; insulation is a build-time decision.
One accountable team from the first sketch to handover, with the things that get buried photographed before they are covered.
The Simfy Homes teamSimfy Homes designs and builds bespoke homes, villas and interiors across Hyderabad and Goa, with one accountable team from first sketch to handover.
