Ribbed Welsh slate clads a domestic extension by Manalo & White


Morgan O’Donovan

In designing a back extension to a Victorian house in London with a well-established, verdant garden, architect Manalo & White selected natural Welsh slate as a cladding that both provides a dark, rugged backdrop for plants and references the near-ubiquitous use of the material as roofing in buildings of the period.

Staves of Welsh slate, approximately 600mm long and 44mm wide, in thicknesses of 10mm and 20mm, were fixed to the brick outer leaf of a cavity wall with heavy-duty adhesive. The ribbed effect gives rise to the architect’s name for the project – ‘Corduroy House’. Welsh slate is also used as a capping piece and for patio flooring.


Full-height glazed, sliding doors give an expansive view of the garden where trees and shrubbery in a variety of planters filter daylight and change the character of the space throughout the day.

The full-width extension enlarges one built in the 1980s, making a dining and living area “that feels like a room within the garden”, suggests the architect. “Lowering the floor internally brings the new rooms level with the garden while increasing the internal ceiling height”. The ‘dialogue’ between the different periods in which the house was built and enlarged is continued with the use of materials such as reclaimed oak flooring and aged door handles, as well as panelled cabinetry and planar stonework in the new kitchen which “create a balance between the older parts of the house, with their distinctive mouldings, and the pared back formality of the extension”, says the architect.

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Manalo & White
Design team
Stephen Beasley, Brian Greathead, Amara Iglesias, Kulsoom Khimjee, Adrien Fouere
Garden designer
MWM Projects
Structural engineer
Structure Workshop
Approved inspector
Shore Engineering
Roy Cox Contracts

DOT Bespoke
Welsh Slate
Glazing Vision
Sliding doors
Architectural Vision Systems
Door ironmongery