By Brian G Newell, Founder and Chief Executive of Shackerley (Holdings) Group Limited
Ceramic Granite – an ideal cladding solution
Ventilated facade cladding is a well established, tried and tested method of enhancing the appearance of a new or existing building whilst protecting it from the elements, extending its lifespan and improving its overall energy efficiency.
Since the early 2000s the choice of ventilated facade options available to the UK specifier has included ceramic granite, a premium quality engineered material made entirely from natural constituents that has proved to be an exceptionally attractive, versatile, long lasting and sustainable external cladding solution.
What type of material is it?
This is a remarkably versatile and technologically advanced construction material, produced entirely from natural elements, combining the practicality and quality of porcelain stoneware with the beauty of quarried stone. It can be manufactured to deliver a highly contemporary appearance or to resemble any naturally occurring stone, but with superior hardness, strength and impermeability.
How is it made?
The natural raw materials – clays, feldspars, minerals and metal oxides – are amalgamated, wet-ground to a fine powder, refined to remove impurities and turned into a homogenised slurry which is then injected at high pressure into a spray dryer and nebulised in hot air.
The dried particles are mixed and then subjected to intense hydraulic pressure – over 12,000 tonnes. The slabs that emerge from the presses are then fired at 1260°C until fully vitrified. During the firing process the constituent parts become irreversibly fused without any need for bonding agents.
The resulting ceramic granite can be left with a natural unpolished finish or be subjected to further processes, depending on the type of surface texture and degree of sheen required.
The entire manufacturing process is precisely controlled to deliver a high degree of uniformity and consistency across production batches, yet every ceramic granite retains it own unique characteristics and there is no pattern repetition (except where intended as part of the design).
Ventilated façade cladding
Since the 1980s UK architects have been using ventilated façades to provide protective, energy efficient and aesthetically pleasing external envelopes for thousands of new build and refurbishment projects in every sector of the market.
Ventilated façade systems offer a remarkable combination of aesthetic and technical benefits for architects, contractors and their clients. In essence, they comprise an outer façade constructed of large open jointed panels, fixed to the outer wall using an aluminium support structure and mechanical fixing system. As the name suggests, a continuous vented cavity is created behind the façade.
Vast array of façade materials available to meet almost any aesthetic brief.
Protection from elements, in particular the aggressive effects of driving rain. Prevents premature weathering and deterioration of the building fabric.
Continuous flow of air in cavity between outer façade and building exterior. Micro-ventilation effect allows building to ‘breathe’.
Reduces amount of heat absorbed through outer walls in hot weather and retains heat effectively in cold winter months. Reduces need for heating and air conditioning and enhances comfort levels inside the building. Installing external insulation in the cavity multiplies these benefits many times, and can dramatically improve acoustic performance too.
Can transform appearance, image and thermal performance of a dated but structurally sound property and extend its life by several decades.
What makes ceramic granite an ideal facade material?
Visually attractive and versatile
Large format ceramic granite panels can now be manufactured in a myriad of attractive colourways and styles, with a wide range of finishes. They can be produced with through-body veining and graining, and with highly polished, honed, satin lustre or natural surfaces, providing attractive and logical alternatives to quarried stone cladding. Recent advances in digital printing technology have led to the development of new contemporary styles featuring the linear graining of natural timber and realistic representations of weathered metals.
Ceramic granite is an impermeable material. Facade panels meet Class B1a, indicating that they have almost zero porosity, in accordance with BS EN 14411. This impermeability makes ceramic granite resistant to all climatic conditions – from blazing heat through to sleet and hail at sub-zero temperatures – and capable of withstanding rapid changes between extremes. The problems often experienced with quarried porous stones, such as algae growth and rain damage are eliminated, and the material is also impervious to airborne pollutants, acids and alkalis.
Strong, light and hard
Because it is a manufactured product, ceramic granite doesn’t have the flaws, fissures and other defects found in quarried stone. Its high breaking strength and modulus of rupture means that large format ceramic granite facade panels of just 11 mm thick offer outstanding building protection. As these cladding panels are so much thinner and lighter than quarried stone cladding, the stress and overall load on the exterior of the building and the facade substructure is minimised. Because the panels are easier to handle, installation time is also reduced.
The material is also exceptionally hard, up to 8 Mohs, which is as hard as tungsten and hardened steel and twice as hard as quartz. This means that the potential for accidental or deliberate damage and abrasion is minimised.
Another strong argument for using ceramic granite in exterior cladding applications is its long-term appearance retention. A facade will retain its appearance throughout its life without special maintenance. Panels are resistant to UV light so they will not fade or ‘weather’ and change colour as other facade facings may do. They are also resistant to most
types of graffiti.
The environmental credentials of the material used in construction have never been under more scrutiny. A Shackerley ceramic granite ventilated facade system can help to enhance a building’s BREEAM rating, with its classification of A+.
The constituents of ceramic granite are all natural. No bonding agents or resins are used in the manufacturing process. No waterproofing chemicals are used, and no lead is used in the polishing processes. Ceramic granite facade panels do not release radon or any other radioactive gases and are completely inert.
The ceramic granite ranges used by environmentally responsible suppliers such as Shackerley are sourced and manufactured in compliance with the European Ecolabel Certification scheme, which deems that products and services are produced respecting specific environmental criteria throughout the life cycle. Ceramic granite manufacturers are continuously striving to increase the recycled content of their finished material. In some cases, the recycled pre-consumer waste content of a facade panel is approaching 40% of the final product. Many ceramic granite facade panels have L.E.E.D. (Leadership in Environmental and Energy Design) credits.
How are ceramic granite ventilated facades installed?
In a ventilated cladding installation facade panels are fixed to an aluminium carrier system which is secured to the outer wall of the building. In order to comply with BS5385 Part 1 & 2, all ceramic facade panels larger than 0.1m2 installed on exterior walls above 3 metres height must be mechanically fixed. Whilst there are various methods of prefabricating facade panels, the use of undercut anchors is the preferred way to provide an invisible, safe, secure and stress–free mechanical fix.
Mechanical fixing methods
‘Face fixing’ clips
This is a simple system but the main disadvantage is that the clips are clearly visible, detracting from the appearance of the façade. They also tend to attract airborne contaminants, and rainwater run-offs show on the face of the tiles.
This system employs clip fixings that require grooves to be made in the edges of the panels or across the backs of the slabs. These can significantly lower the breaking strength of the panels in terms of wind load positive and negative pressure, also hard and soft body impact. Water contaminants lodging in the grooves can ultimately cause frost damage.
(As used in Shackerley’s SureClad® ventilated façade systems)
Undercut anchorage is the most reliable and strongest method of fixing a bracket to a ceramic panel and can be used with panels of all sizes. Undercut anchors are used to attach brackets or straps to the backs of ceramic panels, which are then secured onto a carrier system delivering an extremely robust fix, invisible from the front of the façade.
How are ceramic granite facade panels prefabricated for an anchored system?
Specialist expertise and engineering facilities
The exceptional hardness and strength of ceramic granite means that specialist expertise and engineering facilities are required to transform large format slabs into installation ready facade panels. At its ISO 9001 quality accredited facilities in Lancashire, Shackerley has made major investments in heavy-duty ceramic granite cutting machines and advanced, custom designed CNC precision undercut drilling facilities in order to be able to supply the entire prefabricated ceramic granite ventilated facade system as a single-sourced, ready to install package.
Facade carrier systems
Facade carrier systems are constructed by permanently securing a series of brackets and rails to a structural background, eg, concrete, blockwall, steel frame, etc. With a conventional system, individual facade panels then have to be installed in sequential order.
With its specially designed, anchored aluminium ‘straps’ and uniquely profiled horizontal rails, the patented SureClad® Access system from Shackerley is different. Panels do not need to be installed in strict sequence, and once fixed in place they can easily be removed and replaced in isolation, without disturbing others in the vicinity. This BBA certified, Queen’s Award winning system, offers a number of benefits for the installation team. For instance, gaps can be left in the facade to allow for different types of access equipment to be safely ‘tied’ to the building, and lower courses of panels in the facade can be left until last to avoid accidental site works damage during construction. The simplicity of panel removal and replacement also means that access for maintenance or inspection of any ducting, cabling or other services hidden behind the facade is very straightforward.
The innovative way in which the anchored straps interlock with the carrier system – secured to an upper support rail but slotted into a lower rail without rigid fixing – gives the SureClad® Access system an extraordinary degree of resistance to extreme stresses. It not only complies with all relevant British and European Standards, CWCT standards for systemised building envelopes and NHBC technical requirements, but has also been tested for suitability for installation in regions prone to earthquakes, hurricanes and other climatic extremes.
The SureClad® Access System was recently subjected to a series of seismic tests at Architectural Testing Inc. in Philadelphia to establish its suitability for use across the US. These tests were far more demanding than any required in the UK and were carried out on a ‘Mega Rack’, the largest test apparatus of its type. Components tested on this rig are usually destroyed or badly damaged in the process. Shackerley’s system delivered results that were described as ‘extraordinary’ and ‘unique’ in test reports, enduring a lateral ‘seismic drift’ of over 15cm in each direction and remaining intact.
The façade system was also tested to show that it could withstand simulated hurricane conditions.
Where is ceramic granite ventilated cladding used?
Ceramic granite ventilated facades have literally changed the architectural landscape since Shackerley first introduced this innovative modern method of construction to specifiers, contractors and their clients at the beginning of the 2000s. They have been specified across the the UK (and more recently in the USA, Brazil and Central Europe), to enhance and protect new developments and refurbished properties in every sector of the market – from healthcare, education and civic and public service buildings to hotels, sports and leisure facilities, retail complexes and general commercial buildings.
Specification in the residential sector is also increasing rapidly. Architects, developers and major contractors are choosing to use ceramic granite ventilated facades to clad new multi-dwelling developments ranging from high end private apartment complexes to affordable housing schemes, and to upgrade, modernise and transform the appearance of existing residential properties. A key growth area is the construction of residential accommodation for university students on and off campus.
In every sector this remarkably versatile style of cladding is being chosen for its aesthetic design potential, the speed and ease of facade installation and the long term benefits for clients in terms of asset protection, low maintenance and energy savings.
For more information on any aspect of ceramic granite cladding and the SureClad® range of ventilated façade systems offered by Shackerley please contact the Technical Team on 0800 783 0391 or visit www.shackerley.com