The Mill

House within a house: A mill conversion in the shell of a former threshing mill in the Scottish Borders.

About this project

The Mill formed part of a collection of disused farm buildings tucked into the hillside overlooking the Scottish Borders.

The client’s brief to WT Architecture was to convert the building to create a rural holiday home that while modern, still retained much of its historic character. The client asked for open plan living spaces to be designed to allow different gathering areas, with smaller, more cellular bedrooms fitted into the building’s extended plan so that the living space could be maximised.

A house within a house

With its roof and interior structure beyond repair, the building was stripped back to its shell. Stones from the site were used to repair the original walls which were re-pointed with lime mortar. With the stone exterior stabilised, a new insulated timber building was constructed within, the existing stone walls being used to brace the stick-built structure.

The cavity separating the two wall elements is fully insulated, as is the frame itself, a solution only made possible with an on-site construction method that was able to address the inevitable variation in width between the old and the new.

The elements of the new timber structure visible from the outside are clad in black stained timber, ensuring that they complement, rather than dominate, the original stone walls.

The original front door was reused and enters into a boot room lined in larch. This opens onto a dining room and then onto the main living spaces beyond. Steps lead down a half level to the kitchen, which in turn opens out to a wild garden space.

On the upper floor there are three bedrooms, two accessed from the west stair and one from the east stair, allowing a double height space between to give light to the ground floor.

Use of timber

The upper, timber-clad walls to the long elevations have been designed to rise behind and above the stone parapet to support the roof, whilst a clerestory window has been inserted behind the narrow gap created between the roof and the top of the gable end wall: a neat detail that also clearly distinguishes the modern intervention from the original structure.

Other windows in the black-painted, larch-clad ‘attic’ walls that appear above the parapets to the long elevations have been designed, where possible, to align with openings in the existing stone walls.

Inside, the architects planned a series of simple, utilitarian and durable spaces. The walls are lined with construction grade spruce plywood, while the inner core is coated in white plaster. Meanwhile, the floors are covered with a combination of pine boards and polished concrete.


RIBA House of the Year Award 2015 (sponsored by Grand Designs) - Shortlisted. 
RIAS Andrew Doolan Best Building in Scotland Award 2015 - Shortlisted. 
RIAS Awards 2015 - Winner.
Saltire Society Housing Design Awards 2015 - Winner.
Edinburgh Architectural Association Regeneration and Conservation Award - Commendation.
Historic Scotland Conservation and Climate Change Award - Shortlisted.
Chartered Institute of Builder's Good Building Award - Winner.

Further information

The Modern Timber House in the UK, chapter 2

WT Architecture

Images: Andrew Lee

Key contacts




WT Architecture


John Lawrie Construction

Structural Engineer

David Narro Associates

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