Concrete is one of the most widely used materials for making roof slabs across the world. However, its unsustainability raises major questions about its wide usage. A Madras terrace roof is a traditional roofing technique that is known for being significantly more eco-friendly than concrete roofs. With the advent of global warming and the depletion of natural resources, such techniques are critical for development. Read on to discover the meaning of Madras roofing, its components and construction technique, along with its advantages and disadvantages.
What is a Madras Terrace Roof?
A Madras terrace is a roof construction method using bricks, lime mortar and wooden or steel beams. Believed to have originated in the 15th century in South India—particularly in Madras—this technique was further refined under the British colonial rule. Specifically developed to combat warm and humid climates, Madras terrace construction is an effective way of creating durable and sustainable roofs that are rooted in vernacular architecture.
Madras Terrace Roof Construction
Components of a Madras Terrace Roof
- Bricks: Specially made bricks, locally known as ‘Achikal’ or ‘kandikal’, are the main components of Madras roofing. With a customised size of 1”x3”x6” (25mm x 75mm x 150mm), these bricks visually resemble brick tiles.
- Lime Mortar: A more sustainable alternative to cement mortar, lime mortar has traditionally been used in Madras roofs to create bonding layers between bricks. Lime mortar is a mix of lime putty and sand in a 1:1 ratio by volume.
- Wooden/ Steel Beams: Wooden or steel beams act as the main framework for constructing Madras roofs and help in transferring structural loads to the load bearing walls or other structural elements on which they are supported.
- Lime Concrete: Produced by mixing lime, coarse aggregates (generally brick aggregates for Madras terraces) and sometimes sand, lime concrete is used to fill gaps and create level roof surfaces. The typically followed proportion for this mix is 1:2.5 (slaked lime: broken brick aggregate) by volume.
- Kadukkai/ jaggery mix: Fruits or jaggery are soaked in water for a certain amount of time and this water is then used in traditional Madras terrace roof construction. The use of this mix helps increase the strength, durability and water resistance of the roof.
Madras Terrace Roof- Method of Construction
A Madras terrace roof consists of several layers laid over one another. In the first step, wooden joists or steel beams are fixed to loadbearing walls. These are laid parallel to the shorter side of a room with a spacing of 300-450mm between each other.
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The achikal bricks are then laid in vertical positions over this framework. Laying begins from one corner of the room and continues along diagonal lines by using lime mortar to fix each brick to the next one. Once this brick surface is ready, a layer of lime concrete is poured to even out the surface by removing excess mortar at the top of the bricks. For traditional roofs, a fruit or jaggery mix is poured over this surface to increase the roof’s water resistance and to ensure cooler indoor temperatures. Over this coating, either the final flooring finish or alternating layers of horizontally laid bricks and lime concrete are laid. The number of horizontal brick layers preceding the final flooring finish can differ based on local climatic conditions and structural and design requirements.
Guidelines for the Design of a Madras Terrace Roof
The Indian Standard Code IS 2119:1980 specifies the guidelines for building a Madras roof while maintaining its structural integrity and strength. Some of the important guidelines mentioned in this codebook are:
- All steel beams must be painted with one layer of primer, and the sections of timber beams which are set in masonry must be coated with two layers of hot boiled tar before being fixed.
- All the roof supporting elements, including load-bearing walls, columns and beams, must be properly cured and set before a Madras terrace roof is constructed.
- Bricks must be kept immersed in water for at least 4 hours, then allowed to dry before being used for roof construction.
- The thickness of mortar joints between bricks must not exceed 10mm.
- Once the brickwork is laid, it must be kept wet and cured properly for a minimum period of 10 days.
Why Opt For Madras Roofing?
A Madras terrace roof offers several benefits to modern construction, some of which are:
- Eco-Friendly: The use of locally sourced and naturally available materials like lime, wood and clay (for bricks) makes this roofing sustainable. Conventional RCC roofs, on the other hand, are not environment-friendly due to the high carbon emissions generated by cement manufacture and transport.
- Crack Resistance: Lime mortar is more flexible than OPC (Ordinary Portland Cement), meaning that it allows for slight movements during earthquakes, preventing damage to the bricks and main structure. If any small cracks occur, lime mortar has the ability to self-heal through recrystallisation.
- Thermal Insulation: The major components of a Madras roof (lime mortar, bricks and wood) all have low thermal conductivities. The thickness of such a roof is also generally more than 200mm. These aspects mean that the roof surfaces do not absorb much heat during the day, thus helping maintain a stable and comfortable indoor temperature.
- Aesthetics: A Madras terrace roof does not require plastering or any other form of finishing on its interior surface. Apart from saving time and money, this property can enhance the roof’s visual appearance with the rough exposed surface of bricks.
- Durability and Recyclability: A Madras roof can last for hundreds of years with little maintenance (which includes repainting steel beams or recoating wooden joists to prevent deterioration). Components of old Madras roofing (i.e., beams and joists) can also be dismantled and reused for new construction, making the system significantly recyclable.
- Service Conduits: Unlike conventional RCC roofs where electrical and plumbing lines are concealed, service lines on Madras roofing generally run along the beams or joists. Since these lines are typically left exposed, they are easier to repair or replace in case of any operational issues.
Limitations of a Madras Terrace
Despite their many advantages, Madras roofs have certain drawbacks that limit their usage. Some of these are:
- Cost: Although cheaper than complete steel or wooden roofs, constructing a Madras roof can be considerably more expensive than conventional RCC roofs. This is due to the higher cost of labour and raw materials—like small bricks and lime mortar, which are not usually mass-manufactured—along with the requirement of multiple layers to complete the roof system.
- Building Height: Madras terrace roofs are typically a part of load-bearing structures and thus, cannot be used for mid or high-rise buildings. These roofs can be used only for buildings with a maximum of two or three storeys and are ideal to form the top or terrace floor.
- Spans: This system of roofing cannot be used to span across very large distances without intermediate supports. The maximum span is determined by the size and spacing of the joists/ beams, which are laid parallel to the smaller side of a room. The structural integrity of a building is affected when these joists undergo any deflection or bending due to large spans and loads.
- Labour Requirement: Although many processes—like shuttering and bar bending—that are part of concrete roof construction are not necessary, constructing Madras roof terraces requires skilled labour. A higher number of labourers is also required simultaneously to ensure the uniform laying of bricks and their top layers. Such labour is typically not easily available.
Madras Terrace Architects and Builders
Finding specialist agencies to construct just Madras terrace roofs can be a tedious task. However, Brick & Bolt is one of the leading construction firms in India and provides end-to-end construction services. Being a tech-enabled company, Brick & Bolt is continuously exploring new technologies that can change the meaning of sustainable building. With assured quality control, 7000+ completed homes and a 10 year structural warranty provided, the company has become a pioneer in the industry. Contact Brick & Bolt today to build your home with the most innovative and advanced sustainable methodologies!
Hemali Patel 
Apoorva H P Achar 