European-Manufactured Clay-Block Technology

Joining the European Trend on Sustainability by using 100% Green materials – Precision Engineered Solid Clay Construction blocks.

Why NZ needs to consider the ‘Fabric First’ approach in architecture…

Virtually every day, NZ’s newspapers publish an article surrounding on-going leaking homes or other related issues. We are all well aware of the devastating effects this is having on our country & people. Isn’t it time for a fundamental shift in our thinking?

The ‘Fabric First’ approach is about examining the substrate of our buildings. What is the basic structural element? We know the leaking homes situation has been brought about by a combination of 3 key elements – design, installation & materials. However, by looking at the heart of our buildings, we have to ask ourselves is the substrate able to retain integrity should the design or installation fail?

A building needs to be durable – lasting many lifetimes not just 15-50 years. It needs to be safe, healthy and economic. It needs to provide shelter, comfort, emotional well-being & affordability.

Based in Cambridge, we have been architectural designers for over 20 years having completed many projects across the North Island. We have been involved in Residential & Commercial projects using timber frame, concrete block, rammed earth, solid sun-dried clay and aggregate block, insulated concrete tilt slab, AAC block, insulated concrete block and latterly Wienerberger Porotherm thermally designed kiln-fired matrixed clay construction blocks.  Our passion is to achieve thermal mass, longevity of the build and simple detailing solutions i.e simple exterior building fabrics or the ‘Fabric First’ approach.

We believe that with the introduction of this well-proven European manufactured clay-block technology into the NZ market, we have found one of the best possible answers to the many challenges faced by the NZ construction industry and all this conjures up for specifiers, builders and ultimately end users.

We are particularly inspired by Wienerberger’s development of the e4 House. Designed in conjunction with ARUP (a global firm of Consulting Engineers) –  two years in development, the house demonstrates the future of affordable, sustainable housing – ensuring the design will be just as relevant in 150 years’ time as it is today. We are inspired that this concept provides an innovative blueprint for the house of tomorrow.

ARUP is the organisation behind iconic designs such as the Sydney Opera House and Pompidou Centre, Paris. Working in partnership with the Wienerberger e4 brick house™ this project is named according to its four founding principles:

Economy – To provide a house that is not only financially affordable and accessible but that gives optimum build performance and meets market demand.

Energy – The Wienerberger e4 brick house™ will meet current energy standards and will continue to offer a sustainable environment for its life cycle of 150 years plus. Using a ‘Fabric First’ approach, the house is designed with efficiency in mind from the heating and lighting, down to every individual block.

Environment – A house that minimises its environmental impact, is responsibly sourced and meets level 4 of the Code for Sustainable Homes as standard.

Emotion – A house that people will want to live in, that not only provides flexibility and practicality, but will allow for a higher quality of living.

E4 blockhouse meets NZ’s need for quality, affordable & high performing homes - StellariaNZ - Wienerberger e4 Blockhouse - energy economy environment emotion


Here are some of the reasons why our practice is preferring to design using Porotherm

Sustainability – It has never been more relevant than it is today that as specifiers – we align ourselves with companies who place sustainability at the core of its manufacturing and corporate structure. NZ’s building industry relies on imported building materials to complement our own manufacturers. Wienerberger have a long and impressive history of corporate responsibility to the environment and employees. By 2020, Wienerberger will report zero carbon emissions in manufacturing. We simply cannot afford to continue manufacturing and/or importing goods from companies who do not adopt this global responsibility. Porotherm block is a 100% organic & sustainable, operating at this level without the use of petroleum based ‘add-ons’.

R-values that have real meaning in the ‘built environment’ – Independently assessed by internationally recognised and accredited testing laboratories, Porotherm clay construction block R-values range from R-0.3 up to R-5.4 – using blocks ranging in wall thickness from 65mm to 425mm. Porotherm is utilised in countries with climatic extremes far greater than NZ, ranging from -40 degrees C in Russia to Panama at 40+ degrees C including ultra-high humidity.

Thermal mass ‘breathability’ – Concrete has great thermal mass but it has low hydrometric regulation potential. It also has very high passive air movement generated by negative air pressures or differences in humidity levels throughout its structure. It has the density but not the porosity. Clay construction blocks are 85% clay and 15% recycled raw sawdust that when fired at 1200 degrees C, the block adopts a 15% porosity where the timber particles have burnt away. With a standard 500 x250x250 clay (R25) construction block weighing 18kgs we have a better balance of mass to porosity than is achievable with concrete.

Seismicity – All solid masonry constructions and many SIPS (Solid Insulated Panel Systems) require specific engineering design. Seismically, Porotherm can match or exceed timber frame depending on the seismic zone. Seismic design is essentially the structures’ ability to withstand extreme seismic activity long enough to allow its inhabitants to exit the building to safety. Seismic design of clay construction blocks has utilised data from countries equal to or more severe than within New Zealand. We certainly do not have the monopoly on global seismic activity.

The NZ Climate – high rainfall – On the global rainfall average indices, NZ sits between 3 & 4 highest based on land area. This is the very reason masonry construction or similar, is a welcome alternative While timber frame construction pre-1980 has served us well, over the past 30 years we have seen a burgeoning problem with rotting & compromised structural strength in our timbers. However, our choices have been limited. Even if a masonry structure shows installation and leaking problems – if the building does leak, it will have no effect on the fabric of the building – masonry will never rot or develop toxic moulds.

Solid masonry – wet & cold v dry & warm? Concrete is solid – Clay block is aerated. Concrete blocks are wet, Clay blocks are completely dry at construction. This form of construction block is, along with its plastering systems, fully breathable. High air quality in the built environment is all about passive ventilation – if the building fabric can breathe then the air quality within the structure will be superior. Hermetically sealing any structure against moisture ingress as is standard building practice with concrete masonry and timber-framed dwellings. Without specifically designed passive ventilation systems this continues to be one of the major causes of the build-up of interior toxic moulds and general degradation of the outer building fabric – amply demonstrated by the exponential increase in the installation and use of expensive mechanical ventilation systems.

Affordability – is this construction method expensive? Clay Construction wall comparison build rate is equivalent to the material & labour costs to construct a 140mm timber frame wall with veneer brick cladding. With near-zero energy and maintenance costs, this construction method will save thousands over the lifetime of a building – which has a design life of 150 years. By sheer thermal mass, the building is able to maintain its own even temperature far more easily, minimising the use of high-energy heating methods i.e heat pumps.

Time is money in construction – Concrete v Timber v Clay – The unique construction design and methodology of Porotherm clay blocks allows a laying rate of around 10m2 per man hour depending on complexity of design. At 8 units per m2 as opposed to 12.5 for standard concrete block, this product is 40% faster to lay. At 160kgs/m2 finished wall weight Porotherm has handling and engineering advantages over solid filled concrete block which is approximately 318kgs/m2. Allow just 4% of the water usage that traditional solid filled concrete block has and around 3.5% material wastage you begin to appreciate the real value this product has to offer the building industry at every level. Speed is the bottom line and Porotherm Clay Construction is proving this to builders & contractors throughout the world with projects being finished ahead of time – saving considerable costs in labour.

Minimal energy input and quality of the built structure for the end user is ultimately driven by the simplicity of the building envelope and thermal mass. This product has both.


More Information: Wienerberger 

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