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Wednesday, August 24, 2011

Kerala Roof Design

In Kerala, gabled roofs have always been the symbol of a family's stature in society. Even concrete houses with sloping roofs today proudly sport gables.
Ask kindergarten kids to draw a house and most of them are likely to come up with the picture of a triangle atop a simple square. No wonder, because this basic outline has come to symbolise home and its comforts.

The classic gable - or the triangular façade formed by extending the top end of a sloping roof - dates back to ancient Greece and is found in almost every style of architecture, from the colonial to the contemporary.
In ancient Kerala, the gabled roof was the symbol of a family's stature in society, a statement of style. Traditional families vied with one another to adorn their houses with highly ornate wooden gables carved by expert craftsmen. Each region in the erstwhile state of Travancore had its own style of gable.
Diversity in design
In South Travancore belt, the gable was designed as an extension from the top end of a sloping roof. The beak was provided with a carved triangular façade as in the Padmanabhapuram Palace and the numerous Amma Veedus dotting the heritage areas in the city. In the mid-Travancore region, the gable was curved in the shape of a boat. Further to the North, in what is now Ernakulam and Thrissur, it was a projection from the roof, angling upwards. The protruding end of the gable provides protection from rain.

Apart from the aesthetics, the gable on a roof performs a vital function. "If the roof is the face of the house, the gable is the nose. It helps the house breathe by expelling hot air rising from the bottom level and thereby keeps the interiors cool in summer," explains B. Arjunan, director of Arjun and Associates, a Thiruvananthapuram-based firm specialising in Vasthu architecture.
Precision work
In the traditional style, the construction of a gable was based on precise measurements. Proportionality is the key. For houses, the sides of the triangle have to be at an angle of 33 degrees with the base. This is to ensure that the gable does not disturb the overall dimensions and aesthetics of the roof and the building in general. An imperfect gable can spoil the appearance of a house, just as a deformed nose mars the beauty of a face.

Even concrete houses with sloping roofs today proudly sport gables. To ensure that the utility value is maintained, air holes are provided within the triangular face. Designing gables for a multi-level roof is both a challenge and an opportunity for an architect. Multi-tier gables and those facing different directions add to the elegance of a house. Again, proportionality is the key to the beauty of this design layout.


A gable can add about Rs.2000 to the construction cost of a roof. For multi- level gables, the cost can be as high as Rs.25,000. But for an increasingly culture-conscious society, the additional cost involved in adding a gable is more than made up for by the proud statement of tradition.
That is perhaps why the gable has emerged as the most distinguishing feature of Kerala architecture. Most new tourist resorts, houses and commercial buildings are built to flaunt this design aspect.
Builders have bypassed the problem of providing a gabled roof for a house with a flat terrace. This is made possible by fabricating a metal framework over the terrace to hold tiles or light roofing substitutes like tile-profile sheets. Apart from the enhanced aesthetics offered by the gabled roof, the flat terrace offers another tier of useable space. The steel truss used for fabrication is a better and more cost-effective option than wooden rafters

Monday, August 15, 2011

Kerala Building Rules- Rainwater Harvesting


109A.  Rooftop Rain Water Harvesting Arrangements.-

(1) Unless otherwise stipulated specifically in a town Planning Scheme,  workable rooftop rainwater harvesting arrangements shall be provided as an integral part of all new building constructions for the following occupancies, namely:-
i) Group A1- Residential (with floor area of 100 sq.m or more and plot area of 200 sq.m or more)
ii) Group A2- Special Residential
iii) Group B- Educational;
iv) Group C- Medical/Hospital
v) Group D- Assembly
vi) Group E- Office/Business
vii) Group G1 and Group G2 Industrial (only for workshops, assembly plants, laboratories, dry cleaning plants, power plants, Gas plants refineries, diaries food processing units and any other occupancies notified by the Government from time to time) viii) Group1(1)  Hazardous (Automobile wash stall, automobile Service Stations, Service Garages with repairing facilities and any other occupancies notified by the Government from time to time);
Provided that the floor area to be considered  shall be the total floor area in all floors:
Provided further that, the rainwater harvesting arrangement is not mandatory for thatched
roofed buildings.

2)  The components of workable rooftop rainwater harvesting arrangement as stipulated
in Sub-rule (1) above, shall include:
i) Roof catchment area
ii) Roof gutters
iii) Down pipe and first flush pipe arrangement
iv) Filter unit and
v) Storage tank with provision for drawing water and spillover

3)  The minimum capacity of the storage rank  as stipulated in Sub-rule (2) (v) of the
rooftop rainwater harvesting arrangement shall be at the rate given below:
Group A1- 25 litres/Sq.m
Group A2- 25litres/sq.m
Group B- 50 litres/Sq.m
Group C- 50 litres/Sq.m
Group D- 50 litres/Sqm
Group E- 50 litres/Sq.m
Group F- Nil
Group G1 and Group G2- 50 litres/Sq.m
Group H- 25 litres/Sq.m
Group I- Nil

4)  The municipality shall enforce workable artificial ground water recharging arrangements as an integral part of all new building constructions through collection of roof top rainwater.

5)  The component of workable artificial ground water recharging arrangements as stipulated in sub rule (4) above, shall include:
i) Roof catchment area
ii) Roof gutters
iii) Down pipe
iv) Filter unit
v) Recharge well/percolation pit

6)  Wherever rooftop rainwater harvesting arrangements as stipulated in sub rules (1) to (3) above are provided, additional arrangements for carrying the spill over water from storage tank to recharge well or percolation pit need only be provided

7) The owner(s)/occupier(s) shall maintain the rooftop rainwater harvesting arrangements and artificial ground water recharge arrangements in healthy working condition

8)  The Municipality may, in exceptional cases such as water logging or impermeable subsoil conditions to considerable depths, exempt construction from the mandatory groundwater recharging arrangements.