Some of the key technical aspects of cast stone, including the UKCSA Quality Mark for cast stone, are considered in the Technical sections below, and also in the UKCSA Technical Manual for Cast Stone.
The concern regarding maintaining the quality and standards for cast stone in the UK lead directly to the formation of the UK Cast Stone Association in 1991.
Cast stone products manufactured by an UKCSA Full Member to the Association’s stringent requirements and specification are already supplied to a standard in excess of the BS 1217 requirements. However, the UK Cast Stone Association has introduced its own Quality Mark standard for cast stone, which all UKCSA cast stone manufacturing Full Members are required to comply with as a condition of their membership.
The UK has a long history in the manufacture and use of cast stone and the original British Standard for Cast Stone, BS 1217 dates back to 1945. Although the standard for cast stone has been changed and improved over the years, BS 1217 remains one of the longest standing British Standards which is still in existence.
The UK has gone through a transition period from the Construction Products Directive (CPD) into the full introduction of the Construction Products Regulation (CPR) on 1st July 2013. At that time CE marking became mandatory for certain construction products which are covered by harmonised European standards.
UKCSA Full Members aim to produce products which resemble natural stone as closely as possible. The colour and texture of most natural stone can be matched using crushed rock fines and / or carefully selected and graded natural sands, usually mixed with white cement.
This report describes a two year study carried out to develop a reliable test method and performance specification relevant to Cast Stone products. The research was undertaken by the UK Cast Stone Association and the University of Dundee under the UK government’s Department of the Environment, Transport and the Regions (DETR) “Partners In Technology” programme.
The production of cast stone can be an elaborate process. There are as many variations in the precise way UKCSA Full Members go about their art as there are master craftsmen. But there are three main manufacturing methods, semi-dry, wet-cast and fibre reinforced cast stone.
The correct curing of cast stone is essential to resist damage during transportation and construction, and for its long-term durability and appearance.
A key difference between UKCSA Members and other cast stone manufacturers is the high compressive strength of their products, which makes them significantly more robust and durable.
Cast stone has low porosity and can surpass the capabilities of natural stone on permeability. The absorption of cast stone is measured by the Capillary Absorption Test (CAT).
The linear dimensions of individual regular units should conform to the tolerances given in British Standards, although individual UKCSA Members may specify tolerances that are tighter.
The minimum performance standards established by UKCSA for its manufacturing Full Members are supported by rigorous testing and quality control regimes.
The UK Cast Stone Association (UKCSA) has a guidance note to specifiers and users on the characteristics of cast stone that can influence the choice in terms of supplier and type of cast stone units.
As with any building material, it’s important you can trust the manufacturer and choose a product that meets the relevant standards. Most cast stone manufacturers operate without adequate quality assurance or testing regimes and may not be working to the proper standards. Specify cast stone from this kind of supplier and you could be asking for trouble.
Cast stone is trying to replicate the appearance and character of quarried stone and cast stone items are manufactured with natural products and colour variations are inevitable and should not be a cause for rejection.
Although cast stone elements may get dirty, this is unlikely to cause a problem …
In terms of sustainability, cast stone performs well in both production and within its life cycles. The material is highly durable, non-toxic, re-usable and requires virtually no maintenance or repair over its long lifespan.
Some typical questions about Cast Stone are answered here:
The UK Cast Stone Association (UKCSA) has definitions and descriptions of terms associated with cast stone production, specification and usage: