Turning a dark, inward-looking house into one that opens fully to a coastal view requires more than larger windows. The existing structure imposes boundaries on where walls can move and how circulation can be reorganized. When the starting point is a multi-family house that several households lived in, the interior is typically divided into self-contained units with small openings and limited connection to the outdoors. The passive house architecture approach to retrofit focuses on envelope performance and airtightness, but a coastal renovation must also prioritize view lines, natural light, and seasonal occupancy patterns. The Mirma House in Denia, Alicante, demonstrates how a Mediterranean house can be reimagined from a compartmentalized dwelling into a single home that maximises its seaside location. Built in 2018 and covering 323.73 square meters, the project began from an existing structure that had housed multiple families.
Starting from a Pre-Existing Structure
The project began from a pre-existing condition: a single-family house that had been subdivided for multiple families. The brief was to reconvert it into a single residence that could host many visiting relatives during summer months. This meant undoing decades of compartmentalization while working within the existing footprint. The original house had small openings, dark interiors, and practically no relationship to the surrounding landscape.
Working with an existing structure is fundamentally different from new construction. Load-bearing walls that once separated apartments cannot always be removed. MEP routes that served individual units must be rationalized into a single system. Window openings that were sized for privacy between adjacent units need to be enlarged or relocated. The modern barnhouse vision for new-build projects allows architects to start from a clean slate, but a conversion like Mirma House requires adaptive strategies that work within constraints.
Assessing What to Keep and What to Remove
The first step in any conversion is distinguishing between structure that can stay and partitions that must go. In the Mirma House, the outer walls and floor slabs formed the retained shell, while internal dividing walls between the former apartments were removed to create open living spaces. The ground floor layout was the most constrained because it carried the original distribution of rooms from the multi-family configuration.
Floor Plan Reorganization Priorities
- Remove non-load-bearing partitions between former apartments
- Enlarge existing window openings where structural beams allow
- Add new openings facing the sea where possible
- Create a single stair core that serves the whole house
- Relocate kitchen and dining to the sea-facing side
Expanding Openings for Direct Sea Connection
The project description states that the architects carried out the opposite of what they found, expanding window openings as far as possible to generate direct communication with the exterior. The plot has a totally flat topography, which allows the sea to be visible from all points of the house. Maximizing this advantage meant cutting larger apertures into the existing walls and, in some cases, creating entirely new openings where none existed.
Structural Considerations for Window Enlargement
Enlarging windows in an existing masonry wall requires installing lintels or beams to redistribute the load above the new opening. The wider the opening, the larger the beam needed. A standard window of 1.2 meters width can typically be enlarged to 2.4 meters with a steel lintel, but going beyond that may require a transfer beam or structural frame.
| Opening Width | Structural Requirement | Glazing Type | Relative Cost Factor |
|---|---|---|---|
| Up to 1.5 meters | Standard concrete lintel | Fixed or casement | 1x |
| 1.5 to 3 meters | Steel beam or reinforced lintel | Sliding or folding | 2 to 3x |
| 3 to 5 meters | Transfer beam or portal frame | Sliding or bi-fold | 4 to 6x |
| Over 5 meters | Structural steel frame required | Floor-to-ceiling fixed panels | 7 to 10x |
The Mirma House uses aluminum carpentry from Cortizo, model Cor Vision, for its expanded openings. This system provides slim sightlines that maximize the glass area while maintaining structural performance against coastal wind loads.
Orientation and Solar Heat Gain
Enlarging windows on a sea-facing elevation increases solar heat gain as well as views. In Mediterranean climates, south and west-facing glazing requires careful specification of solar control glass or external shading to prevent overheating during summer months. The Mirma House balances this with overhangs and the material palette that reflects rather than absorbs solar energy.
Color Contrast as a Spatial Strategy
The project uses a deliberate contrast of white and black. The front of the house facing the sea is white, representing light, the sea, and infinity. The back is black, relating to the mountain visible in the distance. This binary palette defines the massing from the exterior and carries through to the interior material choices.
The same principle of using color to define zones applies in the window selection for the farmhouse design, where frame color and glass type reinforce the architectural expression rather than competing with it. In the Mirma House, the color split signals the dual relationship of the house to its surroundings: open and luminous toward the sea, grounded and solid toward the land.
White Exterior for Light Reflection
The white front facade uses Cotegram Cal Liso from Parex Group as the cladding finish. This smooth render reflects sunlight and reduces surface temperatures on the sea-facing elevation. The material also performs well in salt-laden coastal air, resisting the degradation that affects some painted finishes near the sea.
Dark Accents at the Entry and Rear
Access to the house is through the center of the floor, via a cantilever that emphasizes and prolongs the dark textures located at the rear. The cantilever acts as a transition device, moving visitors from the dark entry into the bright interior. This compression-and-release sequence is a classic architectural device that makes the arrival experience more dramatic.
The Staircase as a Sculptural and Functional Core
The stair core is described in the project as a sculptural element presiding over the access area and acquiring great visibility from all points of the house. To achieve this, the architects opened all the daytime living spaces so that the staircase becomes visible from every room on the ground floor. This makes the stair more than a circulation element. It becomes the visual anchor of the interior.
The showcase homes that inspire real-world design often employ a central stair as an organizing element, but in a conversion project the stair position is constrained by the existing slab openings. The Mirma House adapted by using the original stair location and amplifying its presence through material selection and lighting rather than relocation.
Materials Used for the Staircase
- Porcelanosa Xlight pavement on treads and landings
- Porcelanosa Krion for sinks and shower trays in associated bathrooms
- Natural wood detailing from Porcelanosa kitchen line for handrails
Skylight Positioning to Emphasize the Core
To project more light onto the main core of the house, the architects located a skylight of the same dimensions as the staircase in the upper-right corner above it. This overhead light emphasizes the stair volume and draws the eye upward, visually expanding the perceived height of the interior. The matched dimensions between the skylight and the stair footprint ensure that light falls directly onto the full stair area without shadow zones.
The combination of the open ground floor plan, the sculptural stair, and the overhead skylight creates a spatial experience where the interior feels significantly larger than its actual floor area. Passive house design and construction lessons confirm that skylight placement directly above circulation zones yields the highest perceived benefit because the light reaches spaces people move through rather than areas they occupy statically.
Material Selection for Coastal Conditions
Coastal houses face specific material challenges that inland buildings do not. Salt spray accelerates corrosion of metals. Humidity promotes mold growth in poorly ventilated areas. UV exposure degrades sealants and paints faster than in inland climates. The Mirma House specification addresses each of these conditions through targeted material choices.
Cladding and Exterior Finishes
The Parex Group Cotegram Cal Liso render on the facade provides a smooth, non-porous surface that resists salt absorption. The Porcelanosa Xlight porcelain tile used for pavement and exterior cladding offers near-zero water absorption, which prevents freeze-thaw damage in porous tiles. Aluminum carpentry from Cortizo uses thermally broken frames with marine-grade anodized finishes that resist corrosion.
Pool and Terrace Integration
The Mosaico Piu gresite (glass mosaic tile) used for the pool provides a surface that resists chemical degradation from chlorine and saltwater while delivering color stability under intense sun. The integration of pool, terrace, and interior through continuous flooring materials creates the visual extension of living space that coastal houses benefit from during summer months when indoor-outdoor living is at its peak. The passive house remodeling lessons from comparable coastal projects demonstrate that careful material selection at the outset prevents costly remediation later, especially in marine environments where moisture intrusion is the primary cause of building envelope failure.