Case Study – Chorley Street (Sika)

Case Study Chorley Street

Project:                                Chorley Street


Address:                              Chorley Street, Bolton, Lancashire, BL1 4AL


Main Contractor:                  Watson Homes


Architect:                             tadw Architects


Size:                                    490m2


System:                               Sika Sarnafil S327-15EL Lead Grey Membrane, Mech Fixed, Sarnavap  5000E SA VCL, Sikatherm PIR AL Insulation, Warm Roof


About the project

Chorley Street is a brand-new housing development in Bolton. Consisting of more than 100 affordable new homes, this development has had a significant impact on the regeneration of the town Centre and provided affordable homes for local residents. The project was completed in partnership with Bolton at Home and with funding support from Homes England.

The two-, three- and four-bedroom family home are available to buy now through the Government’s Shared Ownership scheme. This is designed to support first time buyers on to the property ladder. The one and two-bedroom apartments are available through several affordable rental options, as well as rent to buy options. Other apartments are reserved to offer affordable rent specifically for people aged over 50.

As part of this housing development, eco-friendly design and environmental factors were very important, in line with Bolton Council’s commitment to meeting the goals set out in the Climate Strategy. As such, the development involved:

  • a flood attenuation system- this is designed to reduce flood risk by capturing rainwater and releasing it slowly.
  • a fabric first approach- during the construction process this approach allows for stronger energy performance.
  • air source heat pumps and mechanical ventilation


Key challenges

There were a number of key challenges that we needed to overcome during the construction at the Chorley Street development. These included:

  • Working to a tight programme
  • Working in challenging weather conditions- when completing the work around the external gutters on each side of the roof we were faced with regular heavy rain, which complicated the installation as this area needed to be dry. In addition when working on Block B, the temperature was significantly low which meant that frost was created on the plywood substrate. This in turn made installation of the VCL difficult.


The system

With our extensive roofing expertise here at Enviroply Roofing, we were hired to install a high-quality roofing system for each of the three apartment blocks. In keeping with the theme of the project each roof was installed to the same specification and design, each with a lead grey Single Ply Membrane, using a Mechanically Fixed Sarnafast system.

Installing the Vapour Control Layer was our first step for each roof, with this being installed on top of a new plywood roof deck. For each roof we opted for the Sarnavap 5000E SA. This is a self-adhesive Vapour Control option that is foil faced and reinforced for maximum protection from trapped moisture and condensation. This was adhered directly to the surface of the roof, in line with the manufacturer’s guidance and recommendations.

On top of the vapour control layer we then installed the Sikatherm PIR AL Insulation layer. This was installed in a staggered bond pattern with lightly butted joints and fastened with telescopic tube fasteners. This insulation option and installation method is designed to offer maximum security and to minimize the amount of heat loss, helping to ensure that the residential property has maximum thermal efficiency.

Finally, we completed each roof with a Sika Sarnafil S327-15EL Lead Grey Membrane. This is a top performing Single Ply option that offers full weatherproof, UV and water protection for any roof. This was again Mechanically installed, and it was also used for all details and flashing too.


The result

On completion of the project all work was tested, and the field inspection was passed with flying colours, allowing the roof to meet the requirements for guarantee.