Granby Rock is a striking, marbled recycled terrazzo made with crushed recycled brick, slate and other waste materials.
Granby Rock was first developed by Assemble and Will Shannon in 2015 as part of the refurbishment of 10 derelict houses in Granby, Liverpool 8. A mobile workshop was set up in the backyard one of the houses. Broken bricks, roofing slates and other waste materials were gathered from skips and cast in moulds to create decorative mantlepieces for the refurbished houses.
Granby Rock is made by combining sand, recycled aggregates, cement, pigment and GGBS – a by-product of steel and iron production – we create an exciting, durable engineering stone suitable for a range of residential and commercial environments.
Granby Rock is handmade using a traditional bench-casting process. Each mix is individually prepared, poured into formwork, reinforced with stainless steel rebar and allowed to cure for 28 days. Once a slab has reached full hardness, we grind and polish it using diamond pads to reveal its unique surface.
For the majority of projects, we produce bespoke formwork – working from drawings, digital surveys, or onsite templates. This means that we cast with minimal material wastage and can accommodate a wider range of shapes and sizes than a traditional cut stone product.
Since all Granby Rock pieces are made to order, we will need outline drawings or dimensions to price a project. However, as a general guideline, pre-cast surfaces are in the region of £500-600 per linear metre + VAT.
For UK orders, smaller pre-cast pieces and fire surrounds are packaged onto pallets and delivered via a kerb-side delivery service. Larger countertops are delivered using a dedicated vehicle with A-frame support.
International orders are dispatched in custom built crates to ensure safe transit.
Granby Rock is produced to the British Standard for pre-cast terrazzo and concrete (BS 5385-5:2009). The standards acknowledge that for bench made pre-cast terrazzo, tolerances of +/- <2mm in terms of thickness, edge length and flatness/twist/bow are to be expected.
Advice should be obtained when particularly close tolerances are required due to the above guidelines being influenced by many factors. Particular attention has to be drawn to the possible difficulties created by an accumulation of tolerances. This is often why a small amount of on-site polishing is needed as part of the installation process. This is commonplace for most experienced terrazzo installers and is part of a bespoke finish.
Our general recommendation is to use a colour-matched flexible mastic joint to allow for any movement in the supporting structure.
If Granby Rock is being installed on a completely solid base in which there will be no movement, they can alternatively be finished with a colour-matched resin joint and polished into the adjacent surfaces onsite to provide a more seamless finish.
We recommend that this option is only pursued if you can be assured of the stability of the subbase to avoid joints cracking in the future.
Terrazzo is a ‘hard finish’ and requires little protection against wear. However, like most stone products, it needs some protection against surface staining.
Granby Rock surfaces are sealed with two coats of Lithofin Stain Stop Plus before being dispatched. The sealant is absorbed into the surface, sealing off pores and hardening the surface to give excellent resistance to staining. Lithofin does not change the surface appearance and some clients choose to use an additional surface finish such as beeswax polish for a brighter sheen or gloss finish.
For regular cleaning, mild abrasive white nylon pads will give the best results, along with a PH neutral cleaning product. It is recommended that the sealant is renewed every 1-2 years to ensure the surfaces retain their original finish.
Please see our full care and maintenance instructions for further details.
We produce all of our pieces to British Standards for precast terrazzo and concrete. This means that there are limits on the maximum length of each cast to prevent warping during the curing process.
The maximum casting lengths based on thickness are:
- <1m @ 30mm (for splashbacks and small surfaces only)
- <1.5m @ 40mm
- <2m @ 45-50mm
In some situations where thinner slabs are required, we can reduce the above thickness by 5-10mm by saw skimming once a piece is fully cured.
For UK projects, we can provide templating and supply & installation services.
We always recommend installation is undertaken by a contractor with suitable experience of working with terrazzo or natural stone products. Depending on site conditions, slabs will sometimes need trimming or joints polishing in and this is best undertaken by a suitable professional.
In addition to our standard mixes, we are able to design completely bespoke finishes. These mixes can utilise our existing materials or incorporate other waste streams reclaimed from your building site or elsewhere.
We can incorporate supplied materials in two ways: firstly, we can place pieces in the face of the mould and combine them with one of our existing base mixes resulting in minimal processing requirements.
The second option is to incorporate the material in the aggregate throughout the mix. For this, it would need to be crushed and graded to <20mm with no fines. This material processing can either be done by your contractor on-site as part of their demolition works, or we can arrange it to be undertaken by a third party, where minimum quantities will apply.