The aesthetics, ease of assembly and maintenance together make the perforated ‘jaali' roof a choice for many occasions, says architect Sathya Prakash Varanashi
Have we ever walked under temporary roofs done with interwoven coconut tree leaves? In rural areas they are a common sight, especially during weddings, festivals, public congregations and such others.
Sun rays filtering through the voids of the leaves, moving across the hall as the sun moves in the sky, and creating a playful interior is a delightful experience to bask under. If designing can source inspiration from nature, such enclosures created with natural materials can also be an inspiration.
There are a variety of jaali blocks, bricks with hollow voids, available in the market. They are placed within mild steel framework, fabricated to the size required, with mortar packing in the joints from above.
Depending upon the area to be covered, the structural design of M.S. frame may get cross beams and edge beams, but the top of all purlin-like horizontal members should be at the same level to take the blocks.
The steel and block junction needs to be water-proofed, to stop water penetration there which may rust the members.
In case minimum light is desired, half of hollow clay block can be used, though it is not a light weight solution. The regular clay jaali blocks are only 2 to 3 inches thick, making their use the most ideal. Inverted T sections are the best, though angles and flats can also be used in various combinations.
The top surface can be topped with glass, where the fabrication can be done to a gentle slope, to avoid rainwater falling inside.
Perforated roofs can give a miraculous touch to the internal skylights and courtyard roofs. While light gets in, it can happen so only through the voids, hence the interiors get a soft touch.
Especially where a single piece of glass is not desirable due to quantity of light, jaali skylight can replace clear or even translucent glass, thereby reducing the quantity of light and controlling the daylight factor.
In case the block size appears large and feels insecure, additional mild steel guard bar rods can be welded into the roof support, creating the window grill type of fabrication, to increase the sense of security.
The jaali roof has a great advantage in being a light weight solution. In case a rooftop enclosure is desired where weight restriction limits our options, jaali roof is a safe choice. If rain can be let in, the roof need not be topped with glass, making the overall roof still lighter.
For air, light, rain…
Jaali roof is a slab for all practical purposes, but can let in all the three - air, light and rain! Hence, it is best suited for outdoor purposes, where there is no further upper floor. Being an assemblage of structural steel and blocks, it is not at all cumbersome like the RCC slab. The aesthetics, ease of assembly and maintenance together make the perforated jaali roof a choice for many occasions.
(The writer is an architect working for eco -friendly designs and can be contacted at firstname.lastname@example.org )