Eco Tiles is an environmentally friendly roofing material made from recycled plastic. Stronger and lighter than clay or concrete tiles, the innovation is a dual solution to plastic pollution and high building costs.

Kenyan environmental scientist Kevin Maina and his team work with 500 informal waste collectors who provide plastics, including high-density polymers and lighter polyethene.

The different plastics are then placed in a custom-made extrusion machine at varying temperatures. This allows the machine to reach the various melting points of the different plastics, mixing them without compromising their integrity and removing the need to melt only certain plastic types at a time. The heating mechanism, done through extrusion, emits zero smoke, and can reach temperatures of 50˚C to 400˚C.

UV stabilisation chemicals are added to increase durability and prevent deterioration of the plastic tiles in the sun. Construction sand is added to improve sturdiness.

The composite molten paste is poured into a mould and compacted into a tile in a 400-tonne press. Conventional tiles are burned in a kiln, which produces carbon emissions, and then need to be cured for up to two weeks.

The press makes a tile in one minute, and Maina and his team can produce up to 1,500 tiles a day. Half a million Eco Tiles have been used to date in the construction of 300 houses. They were developed to look like conventional roof tiles and meet the aesthetic expectations of consumers.

Conventional tiles are marginally cheaper but prone to breakage during transport and installation. Eco Tiles have a higher tensile strength and are lighter – at 2.5kg compared to 5kg for clay and concrete tiles – reducing the amount of timber needed on a roof. They also take less time to install.

Their lifespan of 50 years is equivalent to that of conventional tiles. Eco Tiles can save up to 30% in the cumulative costs of construction.