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Rigid Roof Insulation & Green Architecture

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Rigid insulation is a critical component to consider when selecting the roofing system for buildings or any structures. The insulation material becomes an integral part of the roof assembly and must function in concert with the waterproofing membrane and the structural deck. “The right choice results in successful roof systems that perform over the long term,” says Abdus Saeef, Director, Roof Xperts India Pvt Ltd (RXI).

Polystyrene insulations are one of the most common materials used for roofs. Polystyrene insulation could be expanded or extruded. Expanded polystyrene consists of the polystyrene polymer impregnated with a foaming agent. When exposed to steam at specific temperatures, the material expands and is molded into a uniform, closed-cell insulating material.

Expanded polystyrene insulation is available in any molded form and blocks which are later cut as required for various applications. While, Extruded polystyrene consists of a polystyrene polymer that is processed through specialized extruders where the foaming agent is injected and is entrapped within the polymer. This is then extruded through a dye. Passing through a calibrator gives the desired thickness. It is a much rigid material that can be manufactured in a variety of densities, explains Saeef. The advantage of such insulation is that it cannot be made in lower densities. Like in the case of extruded polystyrene it has to be minimum 30kg. Whether it is a 30kg or 50kg the insulation strength remains almost the same. It is only the load bearing or the compressive strength that increases.

An engineer with over 12 years experience in the Middle East for manufacturing expanded and extruded polystyrene, Saeef joined hands in 2010 with Ajit Koshy who has 15 years experience in the oil and gas sector in Dubai and Singapore, to form Roof Xperts India Private Limited (RXI) in Chennai. They are here to give a complete roof system that incorporates extruded polystyrene and one of the best waterproofing systems and covering surface as the clients requirements.

“XPS is widely used as an insulating material all over the Middle-East where daytime temperatures can rise close to 60oC. Our engineers at RXI have the experience of insulating such roofs with XPS thereby reducing the heat penetration by around 60-70%,” explains Saeef.

But, in India the scene is different, says Ajit Koshy. “People are not familiar with extruded polystyrene as an insulation material. But, once they know it and understand the technicalities they realize how effective this system could be, especially in residences.

“During the daytime, there is a lot of heat on the roof and by the time it radiates through the roof it is evening. What we fail to comprehend is that the roof slab becomes the heat sink and through the night it radiates this heat. In the olden days, the open door and windows used to take away this radiation. But, these days even if we are stuck with the idea of weathering coats, we are using air conditioning. Through the night the AC is actually fighting the radiation coming through the roof. By the time the roof cools, it is day again. Polystyrene which comes over the roof slab, arrests the heat at source. So, the slab does not get heated at all. This gets rid of the traditional weathering course” says Saeef.

Insulation also protects the water proofing material and thereby increases its life span as well. When heat is stopped at source and is not allowed to enter inside the house, the need for an air-conditioning system diminishes. This in turn contributes to environmental health and reduces global warming.

“We have returned to India with an objective of energy conservation. Roof Xperts will supply and apply extruded polystyrene for any and all buildings.”

Advantages of Polystyrene as an insulating material are:

  • 100% recyclable product
  • Increases thermal resistance by 60-70% when compared to roofs using conventional weathering course
  • Tested, tried & proven product in the middle east with harsher weather conditions
  • Removes the traditional weathering course material which weighs over 300kgs per square meter
  • Water absorption <1% by volume
  • High compressive strength – min 300kpa
  • Resistance to chemicals, pests & rodents
  • Protects the waterproof membrane and increases its durability
  • Easy installation
  • Fire retardant
  • Usage of air conditioners is minimized thereby reducing ozone layer depletion
  • Reduces the strain on the structure due to thermal shocks thereby increasing the lifespan of buildings
  • Zero maintenance

Roof Xperts provides expanded and extruded polystyrene for insulation, various kinds of membranes for water-proofing and heat resistant reflective tiles covering the entire roof. But, even with all this, the roof weighs 280kg lighter per square metre with three times more insulation. The water proofing because of the insulation has a life-time warranty.

“Extruded polystyrene is the only product which helps green architects to achieve ‘U’ value of less than 0.5 (U value is a measure of the flow of heat through an insulating or building material): the lower the U-value, the better the insulating ability,” says Ajit.

With over 400 million sqft of buildings under the Green certification proposals, the future is definitely promising as well as challenging.

Ajit Koshy


Abdus Saeef

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