A spiralling concrete staircase connects the 12 platforms that make up this split-level house in San Pedro de la Paz, Chile, by Chilean firm Pezo von Ellrichshausen (photos by Cristobal Palma + slideshow).

Mauricio Pezo and Sofia von Ellrichshausen designed Casa Gago for a pair of engineers and their two children. It has a height of four storeys, but each floor is broken up into separate levels, creating a sequence of rooms that incrementally wind up through the interior.

The raw concrete staircase sits slightly away from the centre of the plan, meaning rooms can differ in size to suit their varying functions.

"The ascending sequence establishes varying degrees of intimacy and proximity between the different domestic functions, which extend from the kitchen or a couple of dining rooms at the ground level to the bedrooms or the study in the top part of the house," said Pezo and Von Ellrichshausen.

An entrance wrapping the corner of the building directs residents straight towards the staircase as they arrive. From the first floor, they can then choose to follow the stairwell up to the top, or can spiral up gradually using extra sets of steps between each of the rooms.

"This stratification leads to the activation of certain rooms according to the time of day and a sort of family interaction throughout the central void," said the architects.

There are no landings on the main staircase, creating a continuous spiral that is lit from above by a circular skylight. There are also no typical doorways, as vertical slices in the walls provide access to each level.

Living and dining spaces are located on the first and second storeys and include one double-height space, while bedrooms and a study can be found above.

Walls both inside and outside the building are clad with pine panels, contrasting with the raw concrete of the staircase.

Photography is by Cristobal Palma.

Here's a project description from Pezo von Ellrichshausen:

Gago House

In the middle of a recently populated suburban area which could be anywhere, this house for a couple of engineers and their two children has a square floor plan divided into asymmetrical quadrants that spiral up to a height of four storeys. Four steps (which add 70 cm in height) separate one quadrant from the next.

Installed at the intersection of the habitable walls that divide the interior is a spiral staircase with a central stairwell, regular steps and no landings. To move between one enclosed space and the next there are two routes: the stairs, which function as a diagonal short cut that intersects the corners, and another gentler one that connects the centres of each enclosed space.

In total there are twelve platforms at different levels, in which a rotation of 360 degrees is equivalent to a whole floor. The ascending sequence establishes varying degrees of intimacy and proximity between the different domestic functions, which extend from the kitchen or a couple of dining rooms at the ground level to the bedrooms or the study in the top part of the house. This stratification leads to the activation of certain rooms according to the time of day and a sort of family interaction throughout the central void.

Except for the base, which contains the earth of the back garden, this wooden house is supported on the central staircase, a robust entity of folded slabs and four reinforced concrete columns that rise through the entire height of the volume. At its base, the centre of the staircase coincides with the diagonal entrance to the house. The massive presence of this composite, disproportionate column is contained by an almost provisional scaffolding of beams and columns of treated wood faced with paneling on both sides. The outer facade is lined with a ventilated sheet of boards and lightly framed glass panels.

Program: Private residence
Location: Cumbres de Andalue, San Pedro de la Paz, Chile
Client: Gabriel Gatica
Architects: Mauricio Pezo, Sofia von Ellrichshausen
Collaborators: Diogo Porto, Constanza Collao, Martina Baratta, Linda Werab
Builder: Aroldo Carrasco
Structural consultant: Luis Mendieta
Building services: Marcelo Valenzuela, Carlos Martinez
Structure: Pine wood, Reinforced concrete
Exterior finishing materials: Impregnated pine boards
Interior finishing materials: Untreated tongue and groove pine boards
Storeys: 4
Site regulation: Suburban area
Plot surface: 415 sqm
Built surface: 241 sqm