Have an imaginative roof over your head
Concrete is not the only option when it comes to choosing material for roofing. Choose the right combination, says GOVIND D. BELGAUMKAR
GREAT IDEAS: Roofs are done with care, to suit the local climate. Mangalore tiles look artistic. Photos: Paul Noronha, By Special Arrangement
IT IS important to know the options available in the choice of materials for roofing to make an informed choice. You may choose anything from Hurdi block and Jack's Arch to wooden and pre-cast concrete roof. Opt different types of roof for different areas of your building, if you like. PropertyPlus discusses different options for you.
Most of us have grown in houses that used Mangalore tiles, reading those alphabets on them, which gave you the hint of their maker, abbreviated. Somewhere down the line, we switched over to the unimaginative concrete roof. Luckily, people are going back to the Mangalore tiles, though not for the whole house. In areas where a bit of leakage (from broken or disjointed tile) is okay, Mangalore tile is used now. Made of compressed mud and burnt under controlled conditions, these tiles are uniform in thickness and pattern. They have a nostalgic appeal, though their maintenance is an issue. The tile can be used in many creative ways you could have a clay ceiling covered with Mangalore tiles for aesthetic appeal. It is best suited for your bathroom, car portico, garden gazebo or your watchman's shed. Mangalore tile needs a neat sub-structure. A metal sub-structure is provided these days avoiding the use of wood, lest there be termite attack.
Buildings such as Mysore Bank and Mayo Hall boast of elegant-looking Jack's Arch roofs. Done by skilled masons, they have a series of arches, each measuring about 2' to 3' in width. Steel beams are used between each arch for reinforcement. Bricks form the arch and there is no need to provide centring while making the pre-cast Jack's Arch. Thus you save about Rs. 12 a sq ft, which is otherwise spent on centring. The arches are levelled on the top using concrete. The arches bear as much as load as the concrete roof. The use of steel is also reduced.
It is an eco-friendly roof. Architects such as Jaisim of the city and Gerard D'Cunnah of Goa use it in some of the structures designed by them. The idea is to save a lot of concrete in the making of a roof. This is achieved by putting a layer of clay block, fly-ash block or hollow concrete block or even Mangalore tiles, arranged side by side with reinforcement between them. Concrete is poured over this layer. About 30 to 40 per cent less concrete is used. When ready, you would see the tiles from inside the house and concrete roof from outside. This roof is heat-resistant.
Called as Baliapatnam clay block by architects, it is a cost-effective alternative. Procured from Kerala, it can be placed on beams.
The T-shaped beams are also supplied by the same manufacturer. Laying this also needs no centring, again a saving of Rs. 12 a sq ft. The blocks have air gaps and hence, heat-resistant.
Pre-cast concrete block
The use of pre-cast slabs and beams can save time and concrete and the cost towards centring. This will also save a lot of time. Pre-cast slabs are quite strong. They can be placed on beams.
Also called AC Sheet, it probably is the cheapest of the roofs. It does not need a meticulously made substructure. But disadvantages are many. Its surface becomes powdery, causing breathing problems and bronchitis. The World Health Organisation strongly discourages it. Yet, for temporary purposes, such as a watchman's shed during the construction of a building, this material could be used.
Other corrugated roofs
Other options are galvanised iron sheet, galvanised aluminium sheet, aluminium sheet, PVC sheets, plastic transparent sheets and mud-reinforced plastic sheets. Most of them could be used for backyard roofing or over the structures that are not used on regular basis or where very secure strong roof is not needed. Plastic sheets lose shape when exposed to heat. PVC sheets fade over time. Mud-reinforced plastic sheets become brittle and crack on impact. Most of these thin sheets radiate heat.
This can only be used for intermediate floors. It is also called wooden attic roof. It is not fire-resistant and is susceptible to termite attack. Wood can bend or warp or rot.
An architect, who took fancy to stone slab roof, has opted for this for his house in Banaswadi. In Kolar district and northern Karnataka, many houses use stone slabs for roof. But you need a crane to carry them and lay the slab in the roof. Hence, they are not considered safe. They are not popular.
A hay grown at Krishnagiri is supposed to be suited for this purpose and has aesthetic appeal. There are disadvantages galore. It cannot be your main roof. Growing pumpkin wine on it could make it heat and fire-resistant. Termites love thatched roof; rodents and snakes too might find it habitable.
Technological advancements in roofing will be discussed in the next issue of PropertyPlus.
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