Case Study- Green Street

Project:             Green Street

 

Address:           Green Street, Radcliffe

 

Architects:       tadw architects

 

Contractor:     Watson Homes

 

Roof size:          Main Roof: 1078m2

                              First Floor Roof: 19m2

                              Roof Terrace A & B:46m2 each total 92m2

 

Roof system:  Main Roof & First Floor Roof:  Alumasc Alkorplan Membrane, mech fixed  lead grey 20year guarantee

 

Roof Terrace A & B: Alumasc Derbigum Built-up Felt System 20 year guarantee

 

The Green Street development was designed as a mixed-use scheme, delivering a total of 132 new apartments alongside commercial units, a bar, and office space for a major company. The project involved the construction of three buildings, with residential accommodation forming the entirety of Buildings B and C, as well as part of Building A. Building B provided 53 affordable apartments for rent, while Building C consisted of 44 rent-to-buy homes. The development contributed valuable affordable housing to the Radcliffe area while also supporting local economic growth through the addition of new commercial and employment spaces.

 

 

Here at Enviroply Roofing, we were pleased to work with Watson Homes on the Green Street residential development in Manchester, delivering roofing installations across Blocks B and C. The project involved the installation of two specialist Alumasc roofing systems, designed to provide high levels of thermal efficiency, weather protection and long-term durability.

 

The main residential roof areas were completed using an Alumasc Alkorplan single-ply system, while the terrace roofs were constructed using a reinforced bitumen membrane warm roof build-up. Both systems were installed in accordance with the project specification and current British Standards, ensuring reliable performance across all roof areas.

 

We began this project on 09/10/24.

 

 

The roofing build-up began with the installation of an Alumasc polyethylene vapour control layer. This 0.25mm polyethylene membrane provides effective resistance to water vapour, helping to prevent moisture migration into the roof structure and reducing the risk of condensation within the build-up.

 

The AVCL was loosely laid across the substrate with 150mm overlaps, with all joints sealed using Alumasc butyl tape to create a continuous vapour-resistant layer.

 

 

Following the installation of the vapour control layer, Alumasc foil-faced PIR insulation was installed as part of a cut-to-falls insulation scheme. The tapered insulation design was used to create the required roof drainage falls while also achieving the thermal performance requirements for the development.

 

The insulation boards were fixed securely in accordance with the project specification, ensuring a stable and even substrate ready to receive the waterproofing membrane.

 

 

To complete the main roof system, we installed the Alumasc Alkorplan F single-ply membrane in lead grey. This 1.5mm reinforced PVC membrane provides excellent durability, UV resistance and long-term waterproofing performance.

 

The membrane was installed across the roof areas and mechanically secured in accordance with the manufacturer’s guidelines, forming a continuous waterproof barrier designed to protect the building for many years to come.

 

 

Detailing and finishing works to the main roof areas were completed in accordance with the Alumasc specification to ensure the roof achieved the required standards of weathertightness, drainage performance and long-term durability.

 

Perimeter areas were secured using Alkorplus Peel Stop Bars, mechanically fixed at all roof edge conditions, changes of plane and upstand locations.

 

Upstands and vertical transitions were formed using Alkorplan F membrane flashings, welded to create a continuous waterproof layer.

 

Pre-coated Alkormetal trims were installed to form robust perimeter terminations and drip edges. All membrane laps were hot-air welded and checked to ensure a fully sealed and weatherproof finish.

 

Roof penetrations were detailed using pre-formed Alkorplan membrane sleeves, welded to the main roof membrane to maintain the integrity of the waterproofing system.

 

 

The roofing build-up began with the installation of the Euroroof Self-Adhesive AVCL, a high-performance vapour control layer designed to resist the passage of water vapour through the roof structure. This self-adhesive membrane forms a continuous barrier that helps prevent moisture ingress and reduces the risk of interstitial condensation within the roof build-up.

 

 

High-performance PIR insulation was then installed above the vapour control layer to meet the required thermal performance standards for the development. For this, Alumasc BGT PIR insulation was used as part of a tapered insulation scheme to achieve the required drainage falls. The insulation boards were bonded using Euroroof PU Insulation Adhesive, creating a secure and stable substrate while contributing to the overall thermal efficiency of the roof construction.

 

 

The waterproofing layer was completed using the Derbigum High Performance Roofing System. This reinforced bitumen system consisted of a Hi-Ten Universal Underlay with a Derbigum Black cap sheet, forming a durable multi-layer waterproof membrane designed to deliver excellent long-term weather protection and resistance to environmental exposure.

 

This type of membrane system is widely used for terrace areas due to its strength, flexibility and proven long-term performance in exposed environments.

 

 

The roofing works at the Green Street development were completed on 17/10/25, to a high standard, meeting the requirements for the 20 year guarantee.

 

By combining Alumasc single-ply technology with reinforced bitumen systems where appropriate, the project achieved a practical and durable roofing solution suited to the different building areas. The completed installation provides a robust roofing system designed to perform effectively throughout the lifespan of the development.