Simon Scott of Haddonstone looks at the different options available when it comes to cast stone and its varied applications
There have been more imitations of stone than any other natural building material. This persistent emulation has been for reasons of economy, availability and fashion. Today, cast stonework is being used by architects as a substitute in the applications where quarried stone is difficult, time-consuming and expensive to employ.
Cast stone is becoming increasingly popular as a cladding material, particularly during the current brick shortage. The distinctive looks and texture of cast stone along with its flexibility of size, shape and colour, means that architectural cladding can be created to suit the precise requirements of a housebuilder or architect.
Cladding and rainscreen cladding is often used purely as a decorative architectural feature to embellish the facade of a building. Manufactured for traditional, classical and contemporary styles of architecture, cast stone cladding is a versatile product suitable for many design constraints. High quality cast stone has been used for cladding building projects such as offices, hotels and restaurants, as well as private houses.
The versatility of cast stone as a cladding or rainscreen cladding was recently demonstrated at Wimbledon High School Rutherford Centre. The dramatic entranceway to the Performing Arts centre utilises custom cladding featuring bespoke wording, cast within the stonework. The cladding offers a more contemporary finish, contrasting with the traditional architecture of the existing school.
The ability to mould cast stone into almost any shape means that cladding designs can be manufactured to suit individual requirements. The beauty of cast stone is that it matures and weathers just like natural stone, yet normally costs significantly less than quarried stone.
The best forms of cast limestone cladding are manufactured using a semi-dry mix that creates a surface texture similar to Portland stone or natural limestone. The principal materials of the finest semi-dry cast stone are limestone, white cement, sand and a very small amount of water, giving the mix a damp feel. A reputable manufacturer will ensure that every single batch of raw material is quality checked to ensure complete control of the production process.
The semi-dry cast material is gradually packed into ingeniously crafted moulds using pneumatic hand tools. The material is usually left overnight to cure before the stone can be revealed in all its glory. Reputable manufacturers will employ a state of the art curing system to prevent water loss and ensure that the product achieves optimum strength in excess of relevant British Standards. Thus architects, developers and private clients can have every confidence in its durability.
There are alternatives to the dry cast mix in the form of wet-cast and fibre reinforced stonework production. The wet cast production technique produces a denser cast stone material with a smoother finish to meet demanding design and performance criteria specified in new build projects. The innovative fibre-reinforced cast stone production benefits from drawn glass fibre which has a high strength to weight ratio. Its thin wall construction and GRC technology means the component weight is reduced by approximately two thirds when compared with alternative cast stone production methods. Fibre-reinforced cast stone is ideal for retrofit, refurbishments, timber frame and new build projects where weight is an issue.
The choice of cast stone material depends on the constraints of the project along with the client’s individual requirements. Cladding and rainscreen cladding can embellish and complement an otherwise perhaps rather ordinary facade, uplifting it to much grander proportions.
Simon Scott is a director at Haddonstone