Paint Your Roof White, Bring The Mercury Down

Bhubaneswar: Painting the roof white being one of the best ways to thwart off the unapologetic summer heat is what denizens here and in most parts of the country swear by.

“We have been painting our roof every year for the last 10 years and the difference is immediate – our top floor feels as cool as the ground floor. It has helped us reduce electricity bills as well,” said Kalpana Mishra, a retired lecturer living in Cuttack. “Some days we need the AC. It is a huge relief,” explained Krithika Behera, a resident of Bhubaneswar who has her roof painted white since the last 3 years.

How it works?

This age-old technique relies on the simple principle that darker colours absorb more light and heat, while lighter colours reflect. White being the lightest colour reflects up to 90% of sunlight (as opposed to traditional black roofs which reflect only 20%) according to whiteroofproject.org and keeps interiors cooler by around 7-15 degrees Celcius.

Great for the environment?

A hot roof (grey or black) also radiates the heat in the evening. By painting the roof white, we can prevent this heat from heating up the city too, something termed as ‘urban heat island effect’. According to Lawrence Berkeley National Laboratory, Berkeley, “White roofs cool the world, offset CO2, and delay global warming” by reflecting the heat back to space. It reduces air conditioning bills by 20 per cent as well. A research at the Swiss Federal Institute of Technology (ETH) in Zurich said that painting every roof and surface white can help reduce overall temperatures of cities by 2-3 degree Celsius. The city of Los Angeles painted its roads white to reduce urban heat island effect.

White roof options:

1. Slaked Lime or Choona (Lasts a season)

Slaked Lime mixed with adhesive (usually Fevicol) is the cheapest solution. It is very effective in keeping the heat away but it doesn’t last when it rains heavily.

2. White cement paint (Lasts a year)

This is also affordable but it lasts better than slaked lime. It needs to be reapplied every year, but it usually requires a single coat of paint every subsequent year. This usually costs around Rs 2000 – Rs 3000 for a 1200 sqft roof.

3. Elastomeric Paints (Lasts more than 7 years)

If you can afford and don’t want to reapply every year, elastomeric paints such as Dr.Fixit Newcoat, Asian Paints Damp Proof, Xcel Coatings Roof Paint, etc are the best solution for you. This paint can last for around 5 years and will water-proof your roof and help increase the life span of it. Some companies like Asian Paints give a 5-year warranty on its elastormeric roof paint that costs Rs 30 per sqft including labour. Elastomeric paints cost around 5-7 times that of cement paint.

4. Ceramic Tiles (Last almost a lifetime)

Putting white ceramic floor tiles on the roof is one permanent solution. Make sure to install vitrified double charged tiles with proper grouting else the tiles can break due to expansion and water absorption. Glazed tiles with high reflective index work better. Tiles can make your roof water resistant and increase life span as well as make it more useful.

Cost: Rs 70 per sqft starting.

5. Green Roof

Growing grass and plants on your rooftop can also help reduce the heat as well as generate fresh oxygen. Make sure your roof structure can withstand the load and also waterproof your terrace properly before implementing.