Low-Rise Social Housing Retrofit, Wythenshawe

Project Overview

Background

Wythenshawe Community Housing Group is Manchester’s largest social housing provider. It takes care of around 14,000 properties and provides homes for over 29,000 people. Its declared purpose is to provide good quality homes and services to its tenants and leaseholders, and to play a leading role in creating safer, healthier communities.

Brief

This 10-month project, which began in December 2024, represented an important step towards achieving the Group’s stated goals. It was conceived as a multi-measure decarbonisation scheme, an important element of which would be in the installation of external wall insulation systems to over 200 occupied homes. Most of them were semi-detached and many of them were of non-traditional designs. They had EPC ratings of band D or lower, but the project’s objective was to raise them to band C or better.

The project was funded by Wave 1 of the Social Housing Decarbonisation Fund (SHDF). All works and designs had to be delivered in accordance with the PAS standards.

Design and Specification:

In accordance with PAS requirements, the design of the EWI systems followed detailed retrofit surveys and assessments. That work included pull-out tests on multiple substrates, which included a mixture of non-traditional archetypes. This not only helped our technical staff to determine the most appropriate systems and designs for specific archetypes; it also ensured that they could take full account of other proposed retrofit measures, such as the installation of new doors and windows.

For the majority of the scheme, the client chose an EWI system comprising Permarock Mineral Fibre Dual Density insulation with Silicone Ultra K finish 1.5mm. Designs were adapted according to the demands of different substrates, which included a large number of homes built to the Cornish Type 1 archetype.

Different finishes were also chosen in order to replicate the properties’ original appearance and to suit the character of different neighbourhoods.

System Characteristics

Permarock’s Dual Density Mineral Fibre EWI system incorporates non-combustible mineral fibre insulation, which achieves an A2-s1,d0 classification in accordance with BS EN 13501-1. It has a thermal conductivity score of 0.036 W/mK and can be applied in various thicknesses to yield the specified performance. In this case, the system comprised a mix of 60 mm, 100 mm, and 120 mm insulation boards.

As with all Permarock Mineral Fibre EWI systems, this system was adhesively bonded and mechanically anchored in order to ensure excellent structural stability and resistance to wind loading.

Permarock’s SiliconeUltra K-Finish was then applied over the mineral fibre insulation to produce an attractive, protective finish. It is a system of organically crosslinked nano-quartz particles and silicone emulsion, and it produces a finish that is light, water-repellent, breathable and resistant to the growth of micro-organisms.

It resists the accumulation of dirt, which is shed during the normal actions of weathering, so its surface tends to remain brighter and cleaner than conventional alternative finishes. It is available in a wide range of colours.

Installation

To facilitate rapid, efficient, quality-focused progress, we provided the Retrofit Installer with site- and system-specific training. Our technicians made regular site visits and remained available throughout the scheme to answer any queries – either in person or via remote communications such as email and telephone.

The design and installation teams subsequently made excellent progress. At the time of writing, the £8.7 million scheme is still ongoing, but it is proceeding on budget and on schedule. The EWI works have been delivered concurrently with door and window replacements, re-roofing, loft re-insulation and the installation of new bathroom ventilation systems.

Result:

U-value calculations for the EWI system as designed suggest that the finished properties will comfortably meet – and potentially exceed – the client’s principal objective. The homes should all achieve an EPC rating of C or better.

The works, as they continue, will make homes warmer in the winter months, and should help residents to make important cost savings on energy.

During the project, Adrian Waywell, Project Manager at Wythenshawe Community Housing Group, said: “This initiative will see over 200 households receive vital decarbonisation measures that will transform their homes and quality of life.”

Client
Wythenshawe Community Housing Group
Specifier
Sustainable Building Services (UK) Ltd
Substrate
Various (multiple archetypes)
System
Permarock Mineral Fibre External Wall Insulation Systems
Finish
Permarock SiliconeUltra K-Finish 1.5mm