The process is similar to making sand castles in that any tiny edge defects are corrected after the mould has been struck.

Heating accounts for a massive proportion of carbon emissions and a great deal of it is wasted energy. Even though the greater proportion of that wasted energy is within poorly insulated existing housing stock, new build housing will play an increasing (and some might say disproportionate) role in achieving our targets.

Damage limitation

Between leaving the production line and reaching the builder, cast stone products can suffer a higher than usual damage rate. I have seen products packed in straw which stand no chance of arriving without chipped edges. The builder then has to decide whether to return the products and wait for replacements, or to bring in a stone doctor to carry out repairs. Forticrete took a fresh look at this age-old problem and solved it in two ways. First and foremost they improved the curing of the semi-dry concrete products during their critical stage, where edge damage is most likely. Instead of simply putting them out in a warehouse to cure over several days, they load all the products produced on the shift into giant, computer-controlled steamers. The combination of gentle heat and moisture hydrates the cast stone and achieves around 90% of its strength overnight – in comparison to the seven days or more that it would normally take. This makes it far less vulnerable to damage when it is moved. It’s also a very environmentally-friendly method of curing the components.

They then inspect the products and pack them in polystyrene and shrink wrap polythene, where the stone continues to harden. By the time it arrives on site, the curing process is complete and the bricklayer or stone mason can carry out his work with more confidence.

The semi-dry process is different from wet cast products in that it uses a sand and cement mix that has the consistency of screeding sand, which sets to give a more natural looking face that can be achieved with a wet cast stone. The mixture is mechanically compacted into wooden moulds and struck before it is cured. The process is similar to making sand castles in that any tiny edge defects are corrected after the mould has been struck. This is an intricate process carried out by skilled craftsmen with plasterers ‘small tools’.

There are three ways to order Forticrete Cast Stone

  1. The Stone in Stock range which, as it sounds, is a range of the most regularly requested dressings – from quoins, cills and lintels to portico kits which come in the most popular ‘Bath’ colour only – but are immediately available;
  2. The ‘standard’ catalogue, which gives you a fuller range of products and colours designed to match regional varieties and styles, and which, typically, will take around four weeks from order.
  3. Made-to-order bespoke stone, which takes more planning but allows you to match exactly. This is a highly-skilled process involving the making of individual moulds in their joinery shop and the matching of aggregate and colours to give as near a match as possible – and there are over 400 colours in Forticrete’s ‘library’. This bespoke service is very popular among builders involved in extensions or new build where there is a planning requirement to match the detailing of surrounding properties.

Matching pointing is achieved through the use of Easipoint mixes which are applied with a large mastic type gun. Easipoint heritage mortar is essentially a lime based mortar, with fine sand and pigment added to give an authentic joint. It’s not commonly known that it is possible to get a structural lintel in semi-dry stone. Forticrete’s structural head has a large diameter stud going through the lower third of it, and this is then tensioned at each end. This overcomes the need to support the outer course with a steel lintel and thereby gives a much more authentic finish.