Man in high visibility jacket laying Porotherm clay block walling
An image of Porotherm blocks being layed with ZeroPlus mortar.

What is Porotherm and why should you use it?

Discover the benefits of Porotherm clay block walling and how you can use it for your next project.

Porotherm clay block walling system is an innovative method of construction with the reassuringly traditional values of clay material, it delivers versatile, high performance, and sustainable walls with full technical support available at all project stages.

Porotherm can be used as loadbearing and non-loadbearing masonry above DPC in party walls, partition walls, inner leaf of cavity walls. It can also be used as the outer leaf of cavity walls when used with an impervious cladding.

Porotherm has been a mainstay of construction across Europe for decades. Since its introduction into the UK in 2008, it has become well established as an excellent alternative to traditional masonry such as concrete blocks, as well as other systems such as timber or lightweight steel frames.

The range of benefits offered by building with Porotherm cover a broad spectrum of subjects from economic to environmental to lifestyle.


Due to the interlocking precision design, the lighter weight compared to other materials and the specialist tools, such as the mortar roller, Porotherm is very quick to build with. An average of 25-30m² per man, per day, is easily achievable, which is much quicker than traditional masonry which is between 12-15m² per man, per day.

  • Floors & roofs can be place without the need for backing up to give the watertight shell.
  • Typically projects can be watertight much quicker, allowing finishing trades to start sooner in the programme.
  • Porotherm is more stable and rigid than traditional masonry construction, allowing single storey height construction in a day.
  • The external skin can be removed from the critical path to allow parallel working.
  • ZeroPlus mortar included with the blocks means building can continue down to temperatures of 0°C, increasing the number of working days available during the winter months.


Construction with Porotherm uses around 95% less water than construction used in traditional methods. In a typical 212m² building, traditional mortar will consume circa 1060 litres of water when compared to just 72 litres for the thin joint mortar that is used with Porotherm.  Therefore, Porotherm projects are much less reliant on the local water supply and the system takes less time to achieve a watertight shell.

  • Porotherm is virtually dry compared with concrete blocks that can come with up to 30% moisture content within the block itself adding to the 1000 litres extra water in the mortar.


The compressive strengths of Porotherm’s core range are typically 10 N/mm², which is more than standard concrete blocks that are usually around 7 N/mm². As clay blocks are versatile, one block can usually fit the majority of requirements, as a result, there is no need to keep multiple blocks on-site, reducing the risk of the wrong block being used and optimising storage space on-site.


Porotherm blocks are generally lighter than concrete blocks, allowing workers to maintain steady production rates without the risk of repetitive strain injuries. Precision engineering means no sharp arrises, reducing the risk of cuts. ZeroPlus mortar applied using the specially designed roller reduces dermatological risk.

  • The system is certified to BS EN 771-1, CE marked and accepted by the NHBC, other insurance providers and holds LABC registration.
  • Porotherm being classed as A1 non-combustible is fire resistant at all stages of construction and in use.
  • Reduced contact with mortar further promotes good site safety and occupational health for the builder.
  • Another health and safety benefit is the elimination of RSI to back and elbow when using mortar from spot boards in the traditional method. 


Used for thousands of years in construction worldwide, clay remains the most sustainable solution for modern buildings. Clay is an inert material that provides no risk to either the environment or end-user. Its natural properties means that it provides a complete, long term sustainability, not only offering increasingly sophisticated low-carbon product manufacture, but giving a building life of over 150 years with little or no maintenance.

Strong and durable, yet lighter and often less of a strain to work with than many of the alternatives, clay also builds-in sound and temperature-control benefits wherever it’s used – creating the ideal internal living environment.

  • 30% of materials from alternative, recycled or secondary sources. (MARSS)
  • Life expectancy of more than 150 years and blocks are recyclable at end of life, for example into hard core.
  • Porotherm benefits from having excellent thermal properties for both heat loss aiding u-value calculations and thermal mass reducing overheating, creating a stable and even all year round internal temperature and hence a comfortable living environment.
  • Builders can achieve higher quality blockwork thanks to the precision engineered blocks and true 1mm bed joints.
  • Porotherm is a breathable material and if used in conjunction with other breathable wall solutions can help to regulate room humidity and benefit from a healthier living environment.


Thermally efficient in helping to regulate variations in temperature; air-tightness is maximised with a parge coat or wet plaster on it's inner face.

  • Acoustically efficient.
  • Fire resistance is outstanding, Porotherm achieves a Class A1 rating.
  • Breathable – can help with regulating room humidity when used in conjunction with other breathable materials.
  • No moisture shrinkage – no disruption to finishes, fewer movement joints (1:20 linear metres) and reduced risk of cracking.
  • On average there is only a 2% wastage provision, improving site waste management as well as offering reduced costs and cleaner sites.
  • With Porotherm there is no need for installation of bed joint reinforcement.


Porotherm can be used for monolithic and cavity wall construction and provides an airtight yet breathable solution using a fabric first approach. It is a strong, stable, adaptable method of construction which allows flexibility in the choice of external facades and systems. Porotherm is classed as a low density (LD) masonry unit in accordance with BS EN 771-1 and as such should only be used above DPC at ground level and be protected by an impervious cladding if used externally. 

  • There is no shrinkage and minimal need for movement joints (typically at 20m centres) meaning less snagging and follow up work required for the builder.
  • There are a fully developed system of lintels, wall ties, parge solutions and fixings.
  • Porotherm blocks and components are readily available through a national distribution network.
  • Wienerberger offers ongoing technical support during design and construction as well as comprehensive training either on-site or at Porotherm training centres.


Find products, guidance and information on how to get the most from your clay block projects.

Find Porotherm products for your project


How do you lay clay blocks?


How does Porotherm compare against traditional materials?


Selection of Porotherm clay blocks

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