Porotherm PTH100 block
First built in 1826, the grade II listed Blackburn Cathedral is one of the most iconic house of worship  in Northern England.

Blackburn Cathedral

In June 2012, the Cathedral announced an £8.5 million plan to construct a Clergy Court and Cloister Garth using Wienerberger's Porotherm clay walling system.

First built in 1826, the Grade II listed Blackburn Cathedral is one of the most iconic houses of worship in Northern England. The site of the cathedral, which was officially consecrated in 1977, has been a place of worship for over a thousand years, dating back to the Norman era, when it became home to the first stone church.

Fast-forward a millennium and in June 2012, the Cathedral embarked on another ambitious first, announcing an £8.5 million plan to construct a Clergy Court and Cloister Garth - the first of its kind in the UK for over 570 years.


The Challenge

With the historical importance of Blackburn Cathedral, considerate material selection was paramount to the success of the project. As well as ensuring that the new building materials complemented the existing structures, the architects at the global firm, Purcell, focused on finding a walling solution that would minimise wastage on-site. Furthermore, with the location of the building at the heart of Blackburn town centre, it was important that the materials would maximise storage capacity and ensure ease of access on a very tight site.

The Solution

To streamline the building process, while respecting the cathedral’s history, the architects at Purcell specified Wienerberger’s versatile Porotherm block walling system.  The system offers a winning combination of precision-engineering and reassuringly traditional building values, which made it a perfect fit for the project, which would bring new life to a true British heritage site. Porotherm’s performance regarding thermal, strength and density also meant that one block type suited all requirements, which reduced storage requirements and ensured easy access for building professionals onsite.

From both a speed of build and an aesthetic point of view during the 18-month project, the Porotherm system surpassed the expectations of both contractor and architect. The speed of the system was exemplified on the Dandy Walk elevation, which required fast completion in order for public highway works to begin. This could not have been completed in the timeframe using traditional building methods. The precise dimensions of Porotherm came to the fore when the render base coat was applied.

Work started on site on 22nd April 2014 with blockwork commencing in April 2015.

The building comprises of a lower ground floor basement and car park with concrete frame up to a podium slab. The ground, first, second and third floor construction comprised of a steel frame system with an external leaf combination of stone, ashlar and 100mm Porotherm with a rendered finish. The roofing was a combination of copper and slate.

Elevations that contained a mix of façade materials meant that Porotherm could only be constructed in between the programming of Ashlar and stone work construction. The contractor’s initial concern was how Porotherm would bond in with the large Ashlar units as well as marrying new building techniques with established traditional methods.  However, as soon as the Porotherm construction started, its potential was soon recognised with it being a lot more versatile than initially envisaged. The engineered dimensions of Porotherm was particularly evident when applying the Baumit MP69 render base coat and from an aesthetic point of view the ability to only provide movement joints at 20m centres worked extremely well with the render finish.

The success of the project was in part attributable to the support and guidance given by Wienerberger’s Porotherm Technical team and masons not only at project start but throughout the build. It was also confirmed that customer service from Wienerberger was excellent with all deliveries on time and no issue with lead times. Due to Porotherm’s performance regarding thermal, strength and density, one block type suited all requirements which helped, given storage space constraints on a very tight site. The use of the system’s bagged ZeroPlus thin joint mortar also removed the need for mortar silos. 1,450m2 of PTH 100 Porotherm blocks and 136 bags of ZeroPlus mortar were used on the project.

Blockwork contractors Lambert Walker, who were using Porotherm for the first time, were pleased with the product and immediately identified its potential, as the elevations mainly constructed out of Porotherm block were constructed extremely fast due to ease of application, the quick setting properties of the mortar and no limitation to build height on each lift. It was also commented that the build process was a lot cleaner process than usual with no usual mortar droppings. They were also pleased with the ability to use one-handed lifts on the blocks and load scaffold out more than that allowed using traditional concrete blocks.

Project Manager, Chris Murphy further commented,“Given my experience of using Porotherm on this very challenging build, I would have no doubts in using it in future projects for John Turner“.

The new building includes a library, a refectory, a conference room, hospitality suite in the Deaner, offices for the Cathedral and a NW Adoption Agency, an enclosed Cloister garth, an underground car park, 4 town houses for the Dean, Cathedral Canons and Director of Music, 6 apartments for Cathedral staff and 6 shared accommodation units for organ scholars. 

The Client,

Canon Andrew Hindley Commented:

“When Wienerberger Porotherm clay walling system was specified by our Architect, he assured us that this modern building material would work well with the Grade II building the new structure would join onto. It has proved itself very well indeed and has enabled not only a speedier build but also proven how well a truly innovative system interlocks brilliantly with the historic fabric of the Cathedral”.

Project Information


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