Richard Bailey, director of The Design Collective Architects, and SIGA Natural Slate Category Manager Gerard Ferris, discuss best practice for achieving a high-quality slate roof on a new-build care home with Architecture Today’s Technical Editor John Ramshaw.
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Windsor Court by The Design Collective Architects (TDC) is a 51-bedroom, new-build care home in Malvern, Worcestershire. Located on a prominent site within a conservation area, the three-storey development is surrounded by residential buildings, including Italianate terraced blocks and individual period properties. The scheme has been designed to blend seamlessly into its suburban context with careful attention paid to its form, scale, massing and materiality. With regards to the latter, white rendered walls are combined with an expertly designed and detailed slate roof from SIGA Natural Slate. TDC Director Richard Bailey, in conversation with Architecture Today’s Technical Editor John Ramshaw and SIGA Natural Slate Category Manager Gerard Ferris, explore the roof design and specification process, including slate selection best practice.
Windsor Court is a new-build care home located in Malvern, Worcestershire
What was the brief and how did you develop the design?
RB: The site at Lansdown Crescent is opposite a Victorian terrace of distinguished Italianate-style homes. These incorporate white, render-finished walls punctuated by tall, narrow sash and casement windows, set beneath distinctive low-pitched slate roofs with characteristic deep overhanging eaves.
We were asked to recreate this style of building with our care home design, which also had to have the appearance of a residential property. We developed the design to make excellent use of the whole site. The stepped linear form of the plan allows all visitors to be welcomed into the reception at the heart of the building with its views out through the cafe to landscaped gardens beyond.
Although this is a large building, by emphasising the verticality within the elevations, complemented by the soft landscaping, we were able to give it a domestic scale appearance. Particular consideration was given to detailing around the windows and doors, which reflects those of the neighbouring properties.
Our materials palette took into consideration historic and vernacular materials used in the locale. We used these to develop a building that responds to the area’s distinctive character, but in a modern way within its residential setting.
SIGA 39 slates from SIGA Natural Slate were specified for reasons of performance and aesthetics
How did you approach the roof design?
RB: The scheme draws heavily on the Italianate detailing that is a feature of the Crescent. In particular, the hipped slate roof, bracketed eaves details and chimney stacks. However, because the plan measures 16-metres front-to-back, the building is a significantly deeper than the residential properties it is trying to imitate.
In order to maintain the building’s domestic scale appearance, we had to ‘slice off’ a portion of the roof at ridge level and infill it with a small area of flat roofing, which is hidden from the street. The addition of hips, valleys and dormers also help to break up the mass of the roof further. These interventions worked well and the slate roof complements those of the neighbouring buildings.
The roof incorporates hips, valleys, dormers and a flat ridge detail
How was the slate selected and what was done to ensure quality and consistency?
GF: When it came to selecting the right slate for the roof, specialist roofing contractor White Roofing Services, working for the main contractor Lawrence Baker, came to SIG. The blue-grey coloured slates on the Victorian buildings are more than likely Welsh in origin, probably from Ffestiniog. SIGA 39 slates are not only very similar in terms of colour, but are also ‘First Selection’, which means they are the best quality slates from their quarry. Consistency of quality was particularly important for this project.
Slate is a lump of rock that has been is split into individual sheets. These are then cut into slates. Being a natural product, variations occur in the thickness of individual slates, particularly in inferior quality slates. This can be a problem if slates of different thicknesses are laid next to each other in the same row, because there will be a gap when the next course of slates is laid above. It also looks ugly and could be a weak spot for wind-driven rain or wind uplift. You can see the issue yourself if you lay a thick book next to a thin one on a table. If you place another book flat on top of these, there will be a gap between it and the thin book beneath.
To overcome this problem, with inconsistent quality slates a slater would normally sort the slates into batches so that they can be laid with slates of equal thickness in each row. The less consistent the slate, the more sorting the contractor will have to do. By using a top of the range, first selection slate, like the SIGA 39, White Roofing Services spent far less time grading and sorting to produce a good-looking finished roof.
The SIGA 39 slates complement the colour and appearance of slates used in the surrounding area
Were there are any other benefits of using SIGA 39 on the project?
GF: Another advantage of using premium quality slates is that their consistent quality makes them easier to cut. This is important for a roof with so many hips and dormers, which require slates to be cut at an angle. As is evident from the quality of the finished roof, the choice of SIGA 39 for the project was definitely the right one.
Contact Details
For more information, please visit the SIGA Natural Slate website.
