Paints & Textures · Sri Lanka
Roof slabs and top-floor walls in Colombo absorb intense solar heat for most of the year, driving up cooling costs and, over time, opening hairline cracks that let water in. Cooltight W SLX 500 Si is an elastomeric, heat reflective waterproof paint that C&S Projects supplies and applies across Sri Lanka — solving both problems in one coating system rather than as two separate products.
Two problems, one coating
Cooltight works through two mechanisms. Its elastomeric film stretches across hairline surface cracks rather than sitting rigidly on top of them, so it continues blocking water penetration even as the substrate expands and contracts with temperature. Its silicon resin base reflects infrared radiation rather than absorbing it, which measurably reduces the heat load transferred into the building through the roof slab or top-floor walls.
For apartment blocks and standalone homes in Colombo, Kotte and the wider Western Province, this combination directly addresses the two most common complaints we hear: leaking terraces after monsoon rain, and top-floor rooms that stay hot long after sunset. Because both problems share the same surface, treating them with one system is usually cheaper than commissioning two separate trades.
The principle behind the reflective side is well documented — it is the same cool roof approach used on commercial rooftops worldwide. A dark, uncoated slab absorbs solar energy through the day and releases it downward into the rooms beneath well into the evening. Therefore the comfort gain is felt most after sunset, which is exactly when a bedroom needs to cool down.
Rainfall makes the waterproofing half just as important. Records from the Department of Meteorology show Colombo receives over 2,000 mm a year across two monsoon periods. A rigid coating that cannot move with the slab will crack again in the first season, however well it was applied.
A silicon resin base reflects infrared radiation instead of absorbing it, cutting the heat load through the slab.
The elastomeric film stretches across surface cracks rather than sitting rigidly on top of them.
Safe to apply on occupied homes and offices, with straightforward curing in humid months.
Holds up to direct exposure on terraces and parapets without the brittleness of aged bitumen.
Suitable surfaces
The system earns its keep on horizontal and near-horizontal surfaces that both bake and pond — flat roof slabs, terraces, parapets and top-floor walls. These are the areas where a rigid coating fails first and where heat gain is most obvious inside.
Where a slab has structural cracking rather than hairline movement, a coating alone is not the answer. In those cases we specify from our waterproofing range instead, and our waterproofing membrane comparison explains how those systems differ.
Explore the range
Cooltight sits within our wider paints & textures range — exterior systems, low-VOC interiors, hygiene coatings, enamels and decorative textures, supplied with application by our own teams.
How we work
C&S Projects surveys the roof or wall area first to identify existing cracks and ponding points, because surface preparation determines how well the elastomeric film performs. We then apply Cooltight as a water-based system, which keeps the process low-odour and safe for occupied buildings. Curing stays straightforward even during Sri Lanka's humid months, and the finished surface resists chemical and alkali attack from standing rainwater.
Ponding is the detail most quotes ignore. Water that never drains will find the weakest point in any coating, so where a slab holds standing water we address falls and outlets before coating. Our waterproofing service covers that remedial work alongside the coating itself.
Access is planned into the programme too. For upper terraces and parapets on taller buildings we arrange gondola access rather than leaving it as an unpriced extra. As a result the quotation reflects the true installed cost from the outset.
Detailing decides whether a roof stays dry. Upstands at parapets, pipe penetrations and the junction where the slab meets a wall are where leaks almost always begin, not in the open field of the roof. Therefore we reinforce those junctions during application instead of relying on the coating alone to span them.
How it compares
Torch-applied bitumen membranes are still common for flat roofs in Sri Lanka, however they add no heat-reflective benefit and require full membrane replacement once damaged. Cooltight combines crack-bridging waterproofing with a heat-reflective, UV-stable topcoat.
It can also be recoated in future without stripping a membrane, which keeps maintenance simple and cheap. For homeowners weighing indoor comfort against leak repair costs, this dual-function system is typically the more economical long-term option. For a wider view of exterior systems, see our silicon exterior paint page.
Local coverage
We coat roofs and terraces across Colombo and the surrounding suburbs — Rajagiriya, Nugegoda, Battaramulla, Kotte, Nawala and Dehiwala — as well as apartment blocks in Colombo 03, 05 and 07. Because our stores sit on Buthgamuwa Road in Rajagiriya, sites across Sri Jayawardenepura Kotte are quick to reach when a leak needs attention before the next downpour.
Building type changes the specification. A single-storey house in Nawala with a small accessible terrace is a different job from a mid-rise block in Colombo 05 where the roof carries water tanks, lift machinery and service runs. For example, coating around plant plinths and pipe penetrations needs detailing work that a flat open slab simply does not.
Having applied coating systems across the Western Province since 2022, we have learned which roofs need repair before coating and which are sound. Therefore we survey first and say so honestly, rather than coating over a problem that will resurface in a season. Browse our completed projects for context.
Colour matters more here than on a wall. A reflective system works by bouncing solar energy away, so a pale finish outperforms a dark one on the same slab. Where a terrace is used as living space and a mid-tone is preferred for glare, we explain the trade-off rather than quietly accepting a colour that undercuts the whole point of the coating.
For apartment blocks, we can phase the work section by section so residents keep access to the terrace and water tanks stay in service throughout. As a result a large roof becomes a sequence of short, predictable stages instead of one long shutdown.
Quick answers
The gain depends on slab thickness, ceiling void and shading, so we avoid quoting a single number. What clients consistently report is that upper rooms stop radiating heat late into the evening, which is when the difference is most noticeable.
Ideally during an inter-monsoon dry window, because the film needs dry conditions to cure between coats. We schedule around Colombo's rain patterns rather than forcing a start date that compromises the finish.
A correctly applied system lasts for years and can be refreshed with a recoat rather than a strip-out. That is the practical advantage over bitumen membranes, which usually need full replacement once they fail.
“Our top-floor bedrooms were unusable by late afternoon, and the terrace leaked every monsoon. C&S Projects coated the slab once and fixed both. The rooms cool down properly after sunset now.”
Our work
Premium coatings, waterproofing and façade finishes delivered for landmark residential and commercial developments across Colombo and Sri Lanka.
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Visit our showroom at 53/3 Buthgamuwa Road, Rajagiriya, or call for a supply-and-application quote. Mon–Sat · 10:30 am – 5:30 pm · Sun closed.
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