Monthly Archives: March 2011
While we seek light from the sky, we definitely will not welcome heat, mosquitoes or rain sprays. So, what is the best cover?
Bring in nature: Create a classic skylight effect
How did the idea of skylight originate in modern buildings? It is difficult to pin down a date or a specific architect as the starting point, but we can try a comical response.
In a crowded locality, when each house was tightly sandwiched with no light seeping in from either side, all that people perhaps could think of was look up and pray, “God, please give us light” As they looked up, the idea of opening to the sky must have originated!
Anyway, while we seek light from the sky, we definitely do not seek heat, mosquitoes or rain spray. Accordingly, adequate care and proper design detailing need to be followed. Theoretically, what a skylight does is to let the air just beneath the glass get heated up, then let it escape through air vents placed there, so that fresh air rises from the bottom. Provision for air vents below the glass is mandatory, it ensures air movement through the building.
Vents could be simple voids in the wall, perforated blocks or even a few round pipe sections inserted into the wall. Without this detailing, the building ends up like a green house for growing vegetables, making living miserable.
Vents can be the easiest route for mosquitoes, hence fixing a mosquito mesh is as mandatory as having vents. These vents with the mesh should be at the highest location, with access to the mesh for periodic maintenance. Naturally, they should be towards the flat part of the terrace.
Also, adequate protection from possible rain sprays into the house should be provided in the form of a small chajja or deeply set vents.
Designing the skylights with the safety factor is another important consideration.
Let not the glass tops be a temptation for kids to play with, so guard them well with no sharp projections of glass from the wall edges.
Using flat terrace
Effective utilisation of the flat terrace despite having the skylights has always been a tricky issue. Of course, one may provide openings along a sloping or curved roof to avoid the discussion altogether; however, most often, they happen on the flat part.
After the staircase room, overhead water tank, may be some sloping roofs and such others, we are not left with much space in small plots.
Residents who need the terrace feel the pinch when the skylight cutout takes away some space too.
While there is no real solution to this problem, strategically positioning all these terrace needs by clubbing them in one area, to get the remaining area in one large parcel, could be a solution. If not, the terrace gets fragmented and would be of no larger use.
One word of caution: while skylights are an exciting mode of creating a better house, indiscriminate use of skylights can be the beginning of problems.
What is the most perfect material for a skylight?
Let us walk into a designer home with skylights spread across the space. The light pouring down from roof, highlighting every object and creating shadows underneath, creates an interior design of its own, without using any costly gadget!
What is the most perfect material for skylight? Well, there is none. Each option comes with its own baggage of problems and potentials. As such, our specific choice depends upon what do we intend to get out of the skylight.
Light of course, yes; but should it be clear direct light or indirect and translucent light? How much of rain, moon and sky we would love to look at? Is the skylight a practical application or also an image of the house?
The best of the lot
Clear glass, fibreglass, acrylic sheets, polycarbonate, multiwall section, glass bricks, Mangalore tiles with glass and perforated or jaali roofs have been attempted in the recent past. Clear glass, about 10 mm thick, is by far the best.
It best exposes the sky and moon; does not make sound under rains and the quantity of light can be controlled by shading sunscreen films. As variations of this idea, tinted glass also can be used. We need to ensure that direct sunlight does not fall on artistic paintings, delicate wood work or the morning newspaper that could be irritating!
On the flip side, the junctions need technically handled silicone joints. Glass may break if not well handled.
How do plastic-based sheets perform? They are easy to use, but perform rather badly compared to glass. Most plastics like fibreglass tend to look flimsy, appear dirty over the years and go brittle with age.
Polycarbonate sheets are better on some scores, but tend to get scratches easily. Though they both can be treated for ultraviolet rays, they tend to let in more heat, make loud sound under rain and fade in colour to show off their age within a few years.
Multiwall sections are two layers of polycarbonates sheets with air gap in between, which reduce heat gain, but are very costly.
Glass bricks or blocks are also in practice, though they are costly and provide only translucent light. If not well fixed, the joints between glass bricks can be a source of leakage over the years.
Mangalore tiles with glass piece within can be tried if we seek a traditional feel, merged with modern skylight! Tile dealers may not routinely keep such glass tiles, hence need to order separately.
Those seeking creative looks may try perforated roofs as skylights. Hollow sections, empty glass bottles or jaali blocks are embedded within the roof or placed after the roof is cast.
A piece of glass on top stops rain. It is the easiest way to create an array of sun beams dancing across the house as the day drifts.
In our eagerness to bring in traditional designs into our larger modern plans, are we forgetting basic principles that may hinder the exercises? Some fundamental questions on installing skylights are answered.
Wish we could have had a simple opening to sky in our house, just like houses in the villages do! The thotty of Karnataka, mutram of Tamil Nadu or nalkattu of Kerala require no detailing for they are more like a gaping hole in the roof. Such basic ideas become complicated in our designed urban homes!
Why are the skylights famous for water leakage? While rural homes simply let rain in, we in cities with sky-lit houses try to stop the rain out. When we fail to do so, the water seeps in and the skylight gets blamed! To resolve this issue, the material on top should be a single piece of glass, sloping one way projecting well beyond the edges of opening. It’s best to avoid complicated shapes and joints. However, if they are inevitable, locate them along some support member, not wider than 3 mm, finished with silicon sealants. In the case of large skylights, these joints also double up as expansion joints, absorbing the minor variation in glass sizes caused by temperature.
Is there a way to test the joints for being water proof? Actually no. It’s the rain water leakage that suggests joints are not leak proof. As such, waiting for rains, then studying the spots of leakage to subsequently plug the holes is still the only way out. It means most skylights leak during the first few rains, which is not a problem, but a clue to a solution! Often the water comes in not from the top glass, but the side vents provided for hot air to escape. The design options for fixing glass or providing vents need to be discussed in detail.
Aren’t skylights less secure? This is a common perception, making people shy away from this excellent idea. All openings in a house are secured with grills, so too are the skylight cutouts. Though nowadays, there are houses without any grills, they are secured through electronic systems or have fierce dogs.
Anyway, most normal houses have mild steel grill work in the skylight too, so they are as secure or insecure as the windows! The glass sits directly on top of the grill, as such gets immediate base support. A few vendors have been supplying aluminium grills, may be more for looks than for security.
Shapes do not matter
Is it worth having plain sloping skylights, when they look so ordinary? Differently shaped skylights sound exciting, but to look at them we need to walk up to the terrace! During the daytime, no shape is visible due to flooding down of light. During night, nothing is visible anyway from the ground floor. Shapes such as globe, pyramid and half-cone only make the fabrication work more complex, lead to more joints and increase potential leakages.
Among the great ideas for modern living, skylights have silently suffered for no mistake of theirs. It is time we give them their rightful place.
All light comes from the sky, but how do we judiciously get it in?
The title of this essay sounds paradoxical. Even a child knows that all the light we get comes from the sky! So, what’s the big deal in saying it loud, you may ask.
Looking for answers, we realise the other paradox. All light comes from the sky, but we need to build roofs for shelter and block all the light. It’s alright, we say, looking at the rows of windows lining up the wall. Then, we live in crowded cities with houses in a continuous row or minimal setback space in between which finally appear like narrow and deep canyons. No house would get any direct light or moving air. Living in a tropical country, we complain about lack of light and put on the electric light.
It could be interesting to know how our elders managed in the past, without electricity. Of course, most buildings were built with small windows and less light, yet they had a wonderful idea in ‘open-to-sky’ spaces, flooding the internal court with light, which then would spread around the building.
From Pompei in Italy to Angkor Wat in Cambodia, be it Japanese houses at Kyoto or a farmer’s home at Melukote, all exhibit one similar characteristic — having openings to sky. Some are large congregation courts especially in public buildings, while many are within the common areas of living or dining , and a few have a light shaft in the kitchen or staircase space.
Though traditionally ‘open to sky’ features were common and have regained popularity with modern homes today, large number of house owners have not yet experienced them. How do we then explain the idea of skylight?
The easiest mode of letting people understand a skylight is by referring to them as windows to sky. While the normal window with is operable is fixed to the wall, the skylight glass has no shutters and is fixed to the roof.
Skylights are ecological features, yet serve other purposes. They are normally provided at the topmost roof position; hence require double height, or a tall atrium in public buildings. However, there is no fixed rule. Many houses have a study or storeroom with small skylights where the room height could only be 10 ft. If the first floor has a skylight, it would be naturally at normal roof position, without double height.
Today it’s fashionable to flaunt a toilet with skylight, which also helps in keeping the toilet fresh and dry. Those with regular habits of worshipping at home enjoy skylights where the deity is kept, ensuring day-long soft light near the idol.
For decades now, thousands of homes have enjoyed the benefits of skylights. Designers have experimented with their concepts, construction, details and materials. There are ideas lost and lessons learnt which could become a separate essay.