FT NEWS

A material made from chips of marble or granite set in a wet concrete bed, terrazzo finds its application in flooring, table tops, wall panels and more.

Terrazzo has been a favourite flooring material in Indian homes for many years. Invented in Venice during the fifteenth century, it is a low-cost material that can be used in kitchen countertops, shelves, bathrooms and floors.

The process of making terrazzo is quite interesting. Chips of marble, granite or even quartz are spread on a bed of wet concrete and allowed to set. The surface is then polished to give it a smooth surface. Chips of any size and colour can be added to the cement mixture, which makes terrazzo a highly customisable material.

This material that originated five hundred years ago has found its way into the modern and contemporary design market and comes in five basic types.

Based on the way terrazzo is constructed on-site, it can be classified into two broader sub-categories. The first type consists of a cement-based underbed for the marble chips, while the second consists of an epoxy resin base instead.

The cement matrix terrazzo is divided into four types:

• Sand-cushion terrazzo

This cost-effective terrazzo is primarily used for flooring in the interiors and is extremely versatile. Over the existing concrete slab of the building, an ‘isolation sheet’ is spread, which acts like a base for the galvanised wire mesh. This mesh holds the ‘underbed’ of the terrazzo topping, which is made of sand and cement. Vertical divider strips are placed at regular intervals between the top layer (the terrazzo topping) and the underbed. The purpose of these strips is to prevent anticipated contraction and to enhance the aesthetics of the colours and patterns of the terrazzo.

Considered the best option for spaces where there is a lot of movement and friction, sand-cushion terrazzo flooring absorbs minor defects and prevents their mirroring to the surface. The overall composition will require a 2.5-3 inch slab depression over which the 0.5 inch terrazzo topping would be set.

Layers from bottom to top: concrete slab, thin layer of sand, isolation sheet, wire mesh, sand–cement underbed, 0.5 inch terrazzo topping.

• Bonded terrazzo

Bonded terrazzo can be used in interiors as well as exteriors. In this case, the terrazzo system has only three basic layers – the concrete slab, a layer of mortar and the terrazzo topping. As the name suggests, the slab and terrazzo topping are ‘bonded’ with the help of a sand–cement mortar layer, which is usually around 1.75-2.25 inches. The mortar easily accommodates the variations or roughness of the concrete slab; hence the quality of the slab is not as critical. Similar to sand-cushion, the terrazzo topping is of a thickness of 0.5 inch.

Layers from bottom to top: concrete slab, cement mortar, terrazzo topping.

• Rustic terrazzo

As the name suggests, rustic terrazzo has a rough exterior that gives it a rustic feel. This makes it a favourable choice for outdoor areas and spaces like pools and fountains. The texture makes it slip-resistant, which is its unique factor, as other terrazzo types have a smoother finish as compared to rustic. Rustic terrazzo finds its applications in varied areas but requires a 2 inch slab depression for installation. Rustic or washed terrazzo is composed using a non-ground, textured cement matrix topping and this system can be combined with bonded or monolithic types.

Layers from bottom to top: concrete slab, sand–cement bed, divider strips, terrazzo topping.

• Thin-set epoxy terrazzo

This non-cement-based system, has a 0.25 inch or 0.375 inch thick resinous topping applied directly over the concrete floor. Generally, epoxy resin is used, although polyacrylate is also a common substitute. As the name and specifications indicate, the terrazzo is thin and light but extremely durable and strong. The system is made up of just two layers – concrete floor and resin topping with a flexible membrane in between them to avoid minor cracks. Zinc, brass, or plastic dividers must be installed above any control joints (gaps present in the slab, which allow the concrete to expand or contract when temperatures change) in the sub-floor so that the terrazzo finish does not crack along the joints. Thin-set epoxy terrazzo has high tensile and compressive properties which have advantages like slip and chemical resistance.

A good choice for both residential and commercial spaces, this terrazzo type has it has unlimited options in terms of colour, patterns, and shapes.

Terrazzo flooring can either be constructed on site as explained above, or terrazzo tiles and slabs can be found in numerous patterns and colours. On the other hand, ready-made (or factory made) terrazzo tiles are available in numerous patterns and colours. So, what’s your pick?