Casa da Matriz

Alcácer do Sal, Portugal

2016–2011

Alcácer do Sal is a small medieval town, 80 km south of Lisbon, located at the gateway to the Alentejo. Crowned by an impressive castle, whose foundations were laid by the Arabs in the 8th-century, the winding streets and alleys of this ancient city cascade down a steep slope on the northern bank of the Sado river. This three-bedroom house is located within the walls of the castle, on a plot adjacent to the Church of Santa Maria, whose foundations are believed to include, at different layers, a mosque and a Roman basilica. The site is a situated in a small and walled hamlet, forming two large rectangles, densely planted with century-old olive trees and slightly sloping towards west.

The house forms a sort of split L-shaped plan, positioned along the northern boundary of the plot and simultaneously creating a courtyard towards the south. The master suite is located on the east side, while the two other suites face west. The intersection of these wings generates the living room and study areas, which, with their fully glazed sliding windows, create a fluid and informal space, as well as providing a passive cooling system resulting from the cross-ventilation. The south wing on the tip of the L-shape is the kitchen and dining area, also with overlapping views towards the courtyard and the landscape.

Counterpoising the whitewashed ancient walls of massive stone rubble and rammed earth that encircle the whole perimeter of the plot, and given the site’s archaeological sensitivity, the house has been devised as a lightweight construction system with minimal foundations, adapted from the standard fabrication detailing. A shallow concrete foundation wall supports a girder-and-joist frame that holds the outer walls and subflooring boards, at the same time generating a ventilated void with accessible drainage and utilities piping. The walls are in composed of a conventional metal stud LSF (light steel frame) system, with drywall on the inside and ETICS (external thermal insulation composite system) with a stucco lucido finishing on the outside, complete with a flat roof insulated and covered with pebble.

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Aerial view

Study model

Site plan

Ground-level floor plan and east elevation

View towards north

Office

Location: Rua da Matriz (Castle of Alcácer do Sal), Portugal
Client: Private
Scope of services: Architecture and landscape architecture
Project brief: Three-bedroom house
Plot area: 1,390 sq. m
Gross floor area: 195 sq. m (plus 10 sq. m annex)
Project status: 2011 (concept design) – 2016 (built)
Photography: Nuno Cera, Promontorio (model and aerial)