Specifying Stone In Construction: Cast Stone Or Natural Stone?

Natural stone has been used in architecture for thousands of years, helping to create some of the world’s most prominent and historic buildings, monuments and works of art. With a long and illustrious history, cast stone became a preferred building material in the eighteenth century, when classically inspired country houses were increasingly popular.

Often regarded as a superlative material, the unrefined, organic composition, stability and appearance of natural stone makes it an established choice in the construction industry.  But sourcing and working with natural stone has its drawbacks, and cast stone offers specifiers an easier to use, more cost-effective alternative.

In this week’s blog we explore the main differences between specifying cast stone and natural stone.  We also discuss why choosing cast stone is often the preferred choice for a broad range of building projects.

  • A luxury property in Esher, featuring many of Haddonstone's stunning architectural designs.

What is the difference between cast and natural stone?

Natural stone has been excavated from the ground via the process of quarrying, whereby stone is raked from the exposed surface of natural rocks. As an organic material that has undergone many years of geological change, all types of natural stone are unique, offering subtle or significant variations in grain, texture and colour.

Today, the most common natural stones that are extracted are limestone, marble, granite, slate, sandstone and travertine. Once excavated, these stones are cleaned, cut into varying shapes and sizes as required, and finished.

Cast stone by contrast a special type of reconstructed stone, produced using a blend of limestone, pigments, additives and cement. The mixture is then poured into specially created bespoke moulds before being cured and/or finished.

Cast stone is defined by the United Kingdom Cast Stone Association as:

“Any product manufactured with aggregate and cementitious binder intended to resemble and be used in a similar way to natural stone”.

  • Extraction and processing of natural stone

    natural stone

What are the drawbacks of specifying natural stone?

Whilst natural stone offers many benefits, there are drawbacks to using it as a construction material. The main issues with specifying natural stone for building projects are:

  • Consistency – naturally occurring imperfections and stratification are very common in natural stone
  • Availability – meeting exact project specifications with a natural material like stone can be difficult
  • Cost – natural stone is very often prohibitively expensive
  • Time – the process of extraction, cutting and finishing is time consuming and can increase project lead times
  • Inflexibility – unlike cast stone, natural stone cannot be moulded into any size or shape, therefore limiting the design and construction options available
  • Carbon footprint – many natural stones are imported into the UK from Asia and southern Europe, which adds significantly to their carbon footprint.
  • Cavendish Bespoke Ltd

    buckinghamshire bespoke project

What are the benefits of specifying cast stone?

Natural stone has been imitated more than any other building material to date.  Cast stone offers an impressive alternative.  Here are some of the main benefits of specifying cast stone:

Appearance

High-quality cast stone has the appearance of natural stone and is almost impossible to distinguish from its quarried equivalent.

Versatility

Because cast stone components are produced using moulds, almost any style and scale can be achieved. This includes highly intricate designs and patterns, which would be impossible to achieve, or prohibitively expensive using natural stone.  Plus, colour, texture and material matching is also possible with cast stone, making it the ideal material for restoration and replication, as well as new-build projects.

  • limestone

Cost

Like for like, as a reconstituted material, cast stone is a far more competitively priced material than natural stone.

Its cost therefore not only decreases project risk, but opens up a wider expanse of architectural possibilities.

Performance

With a minimum cube compressive strength of 35 MPa, cast stone can significantly withstand load.

Durability

Cast stone weathers similarly to natural stone and has sound freeze/thaw resistance, so is easily able to withstand even the harshest of weather conditions.

A joint research programme between the University of Dundee and the United Kingdom Cast Stone Association (UKCSA) on the performance and durability of cast stone found that:
“All Cast Stone products, and particularly when waterproofed, were found to be highly resistant to carbonation.  Efflorescence did not occur in any of the test samples and weathering in Cast Stone was similar to that in control natural stone.  The data also suggests that dry-cast, Cast Stone is no less vulnerable to frost attack than natural stone”.
Find out more about the frost resistance of cast stone in a guest blog by Neil Sparrow, Director of the United Kingdom Cast Stone Association and an industry expert in the manufacture of cast stone products.

Flexibility

One of the most flexible construction materials by far, cast stone allows greater flexibility when it comes to both production and installation.  During manufacture, components can be structurally reinforced with steel, and fixing and lifting sockets can easily be integrated.  Stonework designs can be adapted to meet specific architectural requirements, adding greater flexibility for installation.

Consistency

Unlike natural stone, where stratification can be an issue, cast stone designs can be manufactured to exact colour, textural and material specifications.  This ensures against natural imperfections and achieves a beautifully consistent finish.

Environmental considerations

Building with reconstructed stone is arguably more environmentally responsible.  Quarried stone is naturally-occurring and finite.  The process of extracting natural stone changes the geomorphology of the land, as well as impacting the mined site through noise pollution, erosion, sedimentation and loss of habitat.  The process of cutting and finishing natural stone is also reliant of heavy energy use and creates dust and noise pollution.  Finally, importing many natural stones from Asia and southern Europe means this material has a high carbon footprint.

  • longcliffe quarry image

As part of Haddonstone’s commitment to supporting long-term sustainability and reducing environmental impact, we only source the highest-grade, British natural limestone aggregates to produce our cast stone designs.

We have been sourcing our high-grade natural limestone from Derbyshire-based Longcliffe Quarries for decades.

Like Haddonstone, Longcliffe is a family-owned company, operating with a strong commitment to offering premium quality products and service to their clients.  It is this philosophy, coupled with their dedication to developing new, sustainable ways to manage their sites, that makes them the natural choice as our preferred limestone supplier.

Find out more about the practices undertaken by Longcliffe as part of their environmental management system:

Ethically Sourcing Our Materials Blog

 

…if you are searching for a completely modern material, precision-made, which has weight, ‘gravitas’ and permanence, you will find these qualities in reconstructed stone”.
Sir Terry Farrell CBE FRIBA FRSA FCSD MRTPI, British architect and urban designer.
  • scarborough spa

How durable is cast stone?

Reconstructed stone is much more durable than, for example, Bath stone. Because cast stone it has no natural bed, its surface will not flake and it can therefore withstand even the harshest of conditions.

This is why cast stone was the ideal solution to replace Scarborough Spa’s existing stone parapet, which was badly eroded after years of damage by the North Sea.

Using reconstructed, rather than natural stone, also enabled our team to successfully recreate the highly intricate original parapet design.

The restored parapet of this Grade II* listed property will remain structurally and decoratively sound for many years to come, despite its constant battering by sea air and spray.

Read Scarborough Spa Case Study
  • cast stone

Using Cast Stone In Building and Construction – All You Need To Know

Take an in-depth look into our cast stone manufacturing process, materials and specifying cast stone.
  • Haddonstone restoration at Grade I listed Waddesdon Manor

    waddesdon manor

Why is cast stone used in restoration projects?

Cast stone is the ideal solution for the restoration and replacement of stone that’s been damaged by exposure or neglect.

It is also widely used for the extension of original stonework features.

Find out more about using cast stone in restoration projects in our blog:

Quick Guide To Restoration Stonework Blog
  • front aspect of seanham hall

We are ready to help with your next project

Want to find out more about specifying cast stone as an alternative to natural stone?

Contact our friendly team for a free project consultation today.

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