General Specification

On this page you will find general specification information about the products that we manufacture.

We manufacture all of our architectural cast stone to BS 1217: 2008 & ISO771-5. All of our stone products are produced using high grade limestone and sandstone aggregates, selected for their colour, performance and quality. Cement, pigments and waterproofing additives conform to the relevant British or European standard and where appropriate, our products are CE marked.

• Thermal conductivity (internal) 1.46 W/mK
• Thermal conductivity W/mK (external) 1.56 W/mK
• Dry material density 2050 –2200 kg/m3
• Drying shrinkage 0.06%
• Vapour resistivity 100MNs/gm
• Cube strength (minimum average) 35MPa*
• Fire resistance (minimum) 120 minutes
• Capillary absorption test meets UKCSA specification
• Modulus of elasticity 20–25kN/mm2
• Flatness of plane (not greater than) 0.3% of maximum dimension or 2mm whichever is the greater ±2mm
• Tolerances (up to 600mm) ±2mm
• Tolerances (601mm–1000mm) ±3mm
• Tolerances (1001mm–2500mm) ±4mm
• Tolerances (2501mm–4000mm) ±5mm
• Tolerances (over 4000mm) ±6mm

*Other strengths may be produced as required All dimensions shown are in millimetres (mm) All weights are in kilogram’s (kg).

Compressive Strength

Each of our sites supply three cubes to test the average crushing strength. This complies with BS EN 12390-3 and is no less than 35 MPa at 28 days old. No individual cube has a strength of less than 28 MPa and the figure of 35 MPa represents a 40% increase in compressive strength, over that indicated in the British Standard and is as a result of research carried out by The University of Dundee. Note:1MPa is equal to 1N/mm2.

Fire Properties

Units manufactured in accordance with this Standard are non-flammable, non-combustible, do not give off toxic gases and can provide a barrier to the spread of smoke and flame. Standard values should be referred to for the fire resistance of walls made from units complying with this Standard.

Thermal Conductivity

When requested, we can supply you with the thermal resistance details of your units. This value is obtained either by specific testing or from recognised tables.

Sound Insulation

The sound insulation provided by cast stone built with units to this standard is predominantly influenced by mass per unit area. The density of the units you order can be supplied on request, to enable mass calculations to be carried out.

Sulphate Resistance

Where sulphate resistance is required (normally in unprotected ground or ground containing natural sulphates) the suitability of the units shall be based on the cement type and content.

Capillary Absorption Test (CAT)

Sampling and testing looks to ensure that the mean coefficient of water absorption due to capillary action of the three samples does not exceed 1.0 mg/mm2, with no individual value exceeding 1.3 mg/mm2.

It should be noted that the recent research project undertaken in conjunction with the UKCSA and The University of Dundee has identified that the overall durability of a product is more likely to be indicated by the compressive strength than the CAT figure. The CAT figure is more useful in determining whether a water proofing/damp proofing additive has been included.