INCA Case Study: Stevenage SHDF

Introduction

This insulation scheme was carried out over nine three storey blocks. All blocks were residential in their purpose very central to Stevenage forming an important part of the local council’s housing stock. PJMear carried out these works on behalf of Wates according to the designs of constructive thinking.

The properties in question would all be occupied during the works. They were located at:

• 2-24 Buckthorne Avenue
• 26-48 Buckthorne Avenue
• 1-17 Penn Road
• 19-35 Penn Road
• 37-53 Penn Road
• 55-71 Penn Road
• 85-101 Penn Road
• 103-119 Penn Road
• 121-137 Penn road

Properties & Specification

The buildings’ original construction utilized traditional materials typical of the post-war era, including brick and render. The existing walls on Buckthorn Avenue were solid wall while Penn Road was a cavity brick. The depth of the wall being 300mm in thickness provided a suitable substrate to apply the external weberwall and webertherm systems. After completion the U value calculation brought the standard up to 0.26W/m²K. A great improvement for the residents of the 87 flats.

The specification called for the installation of Webertherm Mineral Fibre System with 1.5 mm Silicone and the Weberwall brick slip system both built up with 120mm dual density board. This would improve the thermal performance of the properties while simultaneously enhancing their appearance.

The work was funded under the Social Housing Decarbonisation Fund so it had to be completed by a Trustmark registered installer, and according to the requirements of the PAS 2030 / 2035 standards. Other works conducted as part of the same scheme included loft insulation with new roofing works and high-performance windows. As this project was seeking and achieved PAS funding this meant record keeping was paramount and adherence to specification/design/retrofit assessment was essential. PJMear provided all the necessary documents to aid the project in support of the PAS standard including pre-installation building inspections, SWIGA insurance backed guarantees, Handover documents, image reporting with meta data stamps and claims of compliance.

Design & Installation Challenges

The design presented by Constructive thinking included comprehensive solutions for all blocks. The requests for information to designs were minimal. The design improved vastly the aesthetic of the blocks and successfully provided the thermal performance it sought to. As with any project there were some challenges that needed to be overcome. Mixed External finishes provided a technically challenging interface that resulted in a finish with clean lines and varying textures meaning the buildings retained their original design features while receiving an improvement.

The design of the weber system was provided by constructive thinking with excellent quality detail drawings. With the robust design and manufacturer support PJMear were able to instal the design accurately and within programme.

Each block had a mix of weberwall brick slip system and webertherm silicone texture finish. The interaction points between these systems provided a slight challenge that was mitigated by a a flashing that provided the necessary overhang and also colour matched the weberwall system.

One of the key challenges was the integration of gas pipes within the EWI system. Instead of running the pipes externally, which was aesthetically unpleasing, a 225mm gas box was installed, with louvre vented covers matching the brick colour to ensure a seamless look. These gas boxes were provided by Sysclad, a bespoke design with a custom colour. The louvre vented boxes allow for the safe escape of any potential build up of fumes. Having the gas works encased in this way also enables maintenance to be carried out without damaging the aesthetic. The colour also changes to reflect the system it was within. A sanded slate matching colour to the weberwall brick slips and a Ral number matching the silicone top coat areas of all the blocks.

The existing walls on Buckthorn Avenue were Solid Wall while Penn Road was a cavity brick. In order to secure the Swiga IBGs a cavity wall tie survey was necessary. Initially the survey failed showing an unsatisfactory number of wall ties. After involvement from Leviat, their brick tie solution was installed meaning the external wall insulation systems would now be mechanically fixed to a stable substrate. The cohesion between Wates, Leviat and, PJMear made this problem highlighted and resolves in a manner that did not greatly affect programme.

Measured Results

The client required that the treated buildings should display excellent thermal performance. The thermal performance of the walls was achieved using the Webertherm and WeberWall EWI systems with 120 mm insulation. This resulted in a calculated U-value of 0.26W/m²K

The client also specified that the system should achieve an A2-s1,d0 ‘reaction to fire’ classification, which the installed system did.

The EWI system has also provided a significant aesthetic improvement to the area. Buckthorn avenue specifically is located alongside a busy road in central Stevenage, what was once an inefficient eyesore is now a low-carbon modern place to call home for the residents of 87 flats.

Project Completion

The scheme was completed on schedule, to the satisfaction of the client and residents.

As a result of the works, residents are now enjoying warmer homes, better living conditions and savings on their routine energy bills. The work has helped to improve the general appearance of the neighbourhood, making it look cleaner and brighter and, as an additional benefit, it has also helped to provide a degree of acoustic insulation.

Client Feedback

Julian Still, Weber:

“Our close collaboration with PJ Mear and Wates ensured that the EWI system was installed effectively, meeting all performance and aesthetic requirements, a good product needs a good applicator, so that the resident can have good quality of life”

Martin Asmantas, Project Manager, Wates:

Wates made the decision to partner with PJ Mear Ltd, to deliver external wall insulation works as part of the Stevenage SHDF WAVE 2 contract introducing energy efficiency measures to 237  existing homes thus transforming many local lives. Our decision seemed to have paid off, as just as our client, Stevenage Borough Council, we are extremely satisfied with the quality of finish achieved to date by our supply chain. We hope to maintain our successful collaboration with PJ Mear while continuing to reduce fuel poverty in the area and contributing to the upscaling of the town under the Stevenage Regeneration scheme to achieve an even Better Stevenage for all its residents. This project has now been fully delivered, we are pleased with PJMear’s contribution.