Residential Property – Finalist in SPRA 2024 awards – Best Refurbishment 2023

The project

This Grade II listed property is an architectural jewel which was designed and built over 50 years ago in a low-key modern style that takes inspiration from the 20s and 30s. The single-storey property is a brick and blockwork structure with rendered walls to blockwork and brickwork painted white. The most striking part of the building’s design is the central entrance hall from which radiates four arms that pinwheel to create separate wings that integrate with the surrounding garden. The building is finished with a substantial flat roof that overhangs the eaves to all elevations, with deep timber-lined eaves and soffit details.

Previous occupants had maintained the house carefully to retain as many of the original details as possible. However, many of the fittings had reached the end of their natural life and the roof was in particular need of urgent replacement. This included the original mineral felt roof which had been installed at the time of construction and now, being over 50 years old, was particularly perished. Debris and moss on the roof were acting as a sponge which prevented water from draining off the area standing water was not moving off the roof gullies. New felting had been applied to upstands and boxed-in service ducts to give weatherproofing where older felt had failed. Water ingress was a significant problem, resulting in water damage to the original, internal fixtures.

The main contractor on the project was Rossmark Construction Ltd. V Works Ltd, as Specialist Registered Installers of RubberBond FleeceBack EPDM, were provided following an installer request.

 

Roof Material Selection:

Due to the history of the property, decisions on material selection for the refurbishment work were an important issue and considerations had to be given to ensure they did not impact upon the character and historic appearance of the building. In areas such as the roof, where original materials could not be saved, appropriate replacements had to be selected which would replicate the colour of the original roof but also offer enhanced benefits. The client wanted a roof covering in a dark colour which was close to the original black of the mineral felt.

Flex-R’s RubberBond EPDM was chosen because it would provide a covering that was respectful and in fitting with the character of the protected structure but also had the flexibility required to work with the complex detailing on the roof such as air conditioning grills. As a cold-applied system, it also removed any fire risk during installation.

The overall roof measured 750 sq/m in total. A warm roof build-up was required over the main living/habitable areas of the build and cold roof build-ups were installed over the garden store, overhanging canopies and boiler room.

• Warm roof build-up – RubberBond FleeceBack, insulation, AVCL, plywood deck, timber firring.
• Cold roof build-up – RubberBond FleeceBack, plywood deck, timber firring.

The complex roof area also contained multiple considerations to work around. Due to the history of the building, new services could not be installed inside the property so, alongside the existing roof mounted structures, a new, central air conditioning duct also ran over the roof span. RubberBond was chosen not only because it met the requirements stipulated by the Local Planning Authority but also because of the inherent flexibility of the membrane which could mould to the different angled edges.

 

Workmanship:

Before work could start on the roof, the old fascia had to be removed by a licensed contractor due to the presence of asbestos. Before work started on installing the single ply, main contractor Rossmark had already stripped back the roof to check condition of the existing rafters and replace where necessary. Rossmark then laid timber firrings to create correct falls and overlaid with a plywood deck ready for the EPDM installation.

On the warm roof area V Works Ltd laid an Air and Vapour Control Layer (AVCL), insulation and then the RubberBond FleeceBack was installed ensuring the membrane was turned up and over the existing upstand and terminated with a perimeter trim. The warm roof area features air conditioning ducts which had to be enclosed with the membrane and protected as part of the roof covering.

On the cold roof areas, RubberBond FleeceBack was applied directly over the plywood. Between the cold and warm roof areas, insulation was installed to form a continuous thermal link between the existing cavity wall and the new roof covering. A VCL was turned up the face of the timber and secured below the ply deck.

V Works Ltd know the importance of training to ensure they deliver a high-quality finish on projects. RubberBond FleeceBack can only be purchased from Flex-R by contractors who are members of our Specialist Registered Installer (SRI) scheme. On this project, the four installers were all SRI installers and had received the relevant product training from Flex-R. Quality of installation was kept consistent throughout the project.

 

Specific Challenges:

As a Grade II listed property, the work and choice of building materials had to be carefully considered for the history of the property. The team at V Works Ltd had to meet specific planning conditions and ensure they achieved a high level of work that enhanced the aesthetics of the home.

The age and design of the roof provided a challenging prospect for the installers. Variable heights on the parapet across the span meant that adjustments were required to ensure it met between 180mm and 230mm above rafter level while at the same creating the correct falls and keeping the roof line below the fascia height. Gutter zones also had to be installed with care to ensure they were laid to falls which were variable across the roof due to the length of the gutter run in places.

However, the amount of equipment on the roof turned a large, flat roof span into a much more challenging prospect. Alongside a raised air conditioning duct, there were also 14 roof lanterns, rainwater gullies, chimney to the boiler and living room and other roof-mounted structures to incorporate into the works.

The choice of membrane has enabled V Works Ltd to reflect the aesthetics and history of the property while working around the multiple raised surfaces. A new insulation scheme has brought the building up to date to meet current building regulations.