Scholes Village, Wigan

Client Wigan & Leigh Housing
Specifier Norfolk Property Services
Substrate Brickwork
System PermaRock Mineral Fibre External Wall Insulation Systems
System 2
Finish PermaRock Silicone Ultra K & R Finishes
Finish 2
Project Overview:

 

Background:

This scheme involved installing external wall insulation to six high-rise residential blocks at Scholes Village in Wigan. The properties were occupied and included five 12-storey blocks, and an additional, more complex 10-storey block.

The scheme was commissioned after the failure of a system previously installed by another contractor.  Failures had occurred on all six blocks and, with a few years, the buildings were suffering from water ingress and dampness on internal walls. They also exhibited algal growth, and cracking and discolouration of the external render. At one of the towers, a large section of rendered phenolic insulation had become completely detached from the building and had fallen to the ground.

 

The Brief:

Keen to allay residents' concerns over the safety of the remaining cladding, Wigan and Leigh Homes (WLH), decided to strip the old EWI system and to install a new, BRE-accredited, SWIGA-approved system in its place. That system would need to be securely affixed, using mechanical and adhesive bonding and, since the towers were all over 11 metres in height, the system would also need to meet the most stringent fire regulations.

 

Design & Specification:

As part the selection process, the mina contractor took the client and its insurers to visit a number of high-rise residential sites where it had previously installed PermaRock EWI systems. These included schemes that had also involved stripping-off failed systems. The specifiers were convinced and duly selected PermaRock Mineral Fibre External Wall Insulation, together with PermaRock Silicone Ultra K & R Finishes.

PermaRock’s Mineral Fibre EWI system is suitable for application onto all building types, including multi-storey residential blocks where the non-combustibility requirements of the Building Regulations need to be met. It features non-combustible (Euroclass A1) mineral fibre insulation boards and is compatible with a range of renders and decorative finishes.

In this case, it was used in conjunction with SiliconeUltra K Finish, which is light, water-repellent and highly vapour permeable. It is through-coloured and resists the accumulation of dirt, so it tends to retain a clean, bright appearance. Moreover, an anti-microbial preservative helps to resist the growth of unsightly moss and algae. It is available in an extensive range of colours and a choice of textures and grain sizes: 1.5mm, 2.0mm and 3.0mm.

 

Installation:

The PermaRock Mineral Fibre EWI system is ideally suited for buildings with a storey height above 11 metres, where a system fire rating of Class A2-s1, d0 or better is required. The system is independently assessed (BRE Certificate 158/12) with a minimum 30 year assessed lifetime. Designed for high rise multi-storey buildings, it has the support of a SWIGA 25-year guarantee.

The specific system chosen for the five 12-storey blocks included 100 mm dual-density, non-combustible mineral fibre insulation system. This featured a brick slip finish on the ground level, and a SiliconeUltra K 1.5mm Finish on the eleven floors above. The sixth block was treated with 110 mm dual density mineral fibre insulation and the same decorative finishes.

 

System Benefits:

  • Exemplary fire performance: non-combustible mineral fibre insulation (Class A1)
  • Fire breaks not required within the insulation system
  • A2-s1, d0 reaction to fire classification (EN 13501-1:2007+A1:2009) with PermaRock SiliconeULTRA K-Finish and with PermaRock Brick Slips
  • Suitable for use on buildings with storeys over 11 metres above ground level
  • Adhesively bonded and mechanically fixed insulation: highest level of resistance against wind loads
  • Mechanically anchored reinforcement layer provides additional structural stability in the event of fire
  • Suitable for use in all exposure locations in the UK, including those classed as having ‘very severe exposure’ (Level 4) for wind-driven rain.

 

Results:

The scheme met with an additional challenge when the failed material was removed and revealed further structural problems. In places, where an older EPS cage system had been removed, the installer had in-filled with terracotta blocks, which proved to be very brittle; an inadequate substrate for a properly anchored EWI system and incapable of supporting the necessary loads.

Consequently, PermaRock designers worked with the installer and a structural engineer to develop a solution that would allow the proper installation of the new EWI system. This entailed stripping out all the failed materials, including the EWI system and the blocks behind, and replacing them with steelwork and non-combustible sheathing board. This then provided a secure substrate over which the EWI system was then applied, ensuring continuity of the thermal envelope, minimal thermal bridging, and a consistent decorative finish throughout.

Aside from that unforeseen challenge, work progressed steadily and effectively. Strict quality control procedures ensured that the exterior wall insulation system was installed precisely to specification.

Resident surveys revealed high levels of satisfaction with the work and the scheme was completed with a record of zero defects and 100% handover success.

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