Renovating an apartment to achieve an open-concept layout while preserving its original structural character requires careful planning and material selection. The STROM Flat project in Prague demonstrates how a 94.6 m2 functionalist apartment was transformed into a light-filled living space that celebrates its existing concrete girder ceiling, oak parquet floors, and black terrazzo windowsills. For residential renovations involving concrete elements, understanding tilt-up concrete panel forms and their structural behavior provides useful context for evaluating which existing features can be exposed and incorporated into a new design. This article explores the strategies used in this type of apartment renovation, from layout planning to material coordination.
Planning the Layout for Open-Concept Apartment Living
The first challenge in apartment renovation is reshaping the floor plan to create a sense of airiness without sacrificing privacy. In the STROM Flat, the original layout required a complete reconstruction to achieve a large, longitudinally illuminated living space. The owners wanted to separate daily activities so household members would not disturb each other, which called for a layout where sightlines pass through the apartment while functional zones remain distinct.
Balancing Openness with Spatial Separation
A well-planned open-concept layout uses visual connections rather than walls to divide spaces. In this project, the design team positioned the kitchen at the center of the layout with a solid oak dining table that naturally separates the living room from the office area. This approach avoids the cost and structural complications of adding new partitions. For apartments in multi-story buildings, the flat plate floor system commonly used in such construction provides the uniform ceiling heights that make open-concept layouts feasible without stepped floors or dropped beams.
Key Factors in Open-Concept Layout Planning
- Natural light distribution – orient the main living zone toward the largest windows and allow light to penetrate deeper into the apartment through open sightlines
- Traffic flow – ensure clear pathways between zones that do not cut through seating or dining areas
- Acoustic separation – use furniture placement and soft materials to buffer sound between activity zones
- Visual continuity – maintain consistent floor and ceiling finishes across connected spaces to reinforce the sense of a single large room
The STROM Flat benefits from large windows that allow views of green treetops from the central living area. This connection to the exterior was achieved by adjusting the layout so that sightlines extend through the apartment and out toward the greenery beyond the windows. See-through views between interior spaces and toward the exterior became a defining design principle.
Exposing and Preserving Concrete Ceiling Structures
One of the most striking decisions in this renovation was to expose the concrete girder ceiling structure. The original ceiling had a beautifully crafted concrete girder system with visible formwork patterns from the wooden boards used during pouring. Rather than covering this with a suspended ceiling or drywall, the design team made it the central visual motif of the apartment. Projects like the shipwreck tower in the Czech Republic show how exposed concrete can become a defining architectural feature in both new construction and renovation contexts.
Preserving Concrete Girders and Formwork Patterns
Exposing a concrete ceiling requires careful evaluation of the existing structure. The process involves removing any previous ceiling finishes, assessing the concrete for cracks or spalling, and cleaning the surface without damaging the formwork texture. Key considerations include:
- Structural assessment – have a structural engineer verify that the exposed girders are sound and not hiding reinforcement corrosion
- Surface preparation – remove loose material and old paint using gentle methods such as low-pressure water washing or dry ice blasting
- Sealing – apply a breathable clear sealer to protect the concrete from dust and staining while maintaining its natural appearance
- Integration with services – route electrical conduits, data cables, and lighting tracks along ceiling profiles using metal pipes that complement the industrial aesthetic
| Surface Treatment | Best Application | Visual Result | Maintenance Level |
|---|---|---|---|
| Clear matte sealer | Indoor ceilings, exposed aggregate | Natural gray with visible formwork | Low |
| Lime wash | Historical buildings, textured surfaces | Whitewashed, softened texture | Moderate |
| Polish and grind | Modern interiors, smooth finish desired | Glossy, refined surface | Low |
| Painted (breathable masonry paint) | Covering stains or uneven coloring | Uniform color, hides formwork | Moderate |
In the STROM Flat, the concrete girders were left largely untreated, allowing the original drawing of the wooden formwork to remain visible. This approach respects the building's functionalist heritage and eliminates the material cost of a finished ceiling.
Material Selection That Complements Existing Finishes
Once the concrete ceiling was established as the anchor element, the remaining material palette was chosen to complement rather than compete with it. The design team selected a restrained combination of white, black, metal, concrete surfaces, and oak wood. These materials follow the existing details of the apartment, including the renovated oak parquet floors and the massive black terrazzo windowsills. Understanding flat slab construction and design principles helps renovation teams determine which structural elements can be exposed safely and how material loads are distributed through the floor system.
Choosing a Consistent Color Palette
A limited color palette creates visual coherence across open spaces. In this apartment, the warm tones of the restored oak parquet floors balance the cool gray of the concrete ceiling. White walls reflect natural light from the large windows, and black elements in the window frames, metal conduits, and light fixtures provide contrast without adding visual clutter.
The Role of Metal and Glass Accents
Metal elements appear throughout the apartment in the form of cable conduits routed along ceiling profiles, switch plates, handles, faucets, and light fixtures. The switches and sockets chosen for this project are from the Berker range 1930, designed to echo classic rotary switches. These details maintain the industrial character established by the concrete ceiling while keeping the overall look curated rather than raw. Glass elements and reflective surfaces help bounce light deeper into the apartment, reinforcing the airy atmosphere the owners requested.
Zoning Open Living Spaces for Multi-Functional Use
A central challenge in open-concept apartment design is defining zones without building walls. In the STROM Flat, the design team used a long library unit that passes through the entire width of the layout as the connecting furniture element in the main living space. This single piece anchors the room while providing storage and display surface across multiple zones.
Using Furniture as Room Dividers
The solid oak dining table at the kitchen's center acts as a subtle boundary between the living room and the office area, which was later converted into a children's room. This strategy avoids the cost and permanence of built partitions while giving the occupants flexibility to reconfigure the space later. Effective zoning strategies for renovation projects also require addressing waterproofing for flat RCC roofs when the renovation includes roof access or top-floor apartments, as moisture protection is essential for preserving exposed interior materials.
| Zoning Method | Example Application | Cost Level | Reversibility |
|---|---|---|---|
| Furniture placement | Sofa back facing dining area | Low | Easily reversible |
| Area rugs | Defining living zone on parquet floor | Low to moderate | Easily reversible |
| Partial-height shelving | Library unit spanning the room width | Moderate | Reversible with effort |
| Glass partitions | Separating bedroom from living zone | Moderate to high | Reversible |
| Sliding doors | Enclosing office or children's room | Moderate | Reversible |
The bedroom in this apartment is located in a separate block connected to a day-lit bathroom. This arrangement provides acoustic privacy for sleeping areas while keeping the visual openness of the main living space intact. The separation block approach works well in apartments where a full wall would block too much light.
Bathroom Design with Natural Tones and Concrete Accents
The bathrooms in the STROM Flat continue the material language established in the main living area. Walls are lined with a matt ceramic mosaic in fine tones of cream and dim green. These muted colors provide a calm backdrop that contrasts with the rougher concrete elements. The concrete washbasins and concrete screed flooring introduce the same raw texture found on the ceiling, tying the design together.
Tile Selection for Bathroom Walls and Floors
Choosing the right tile finish for a bathroom renovation involves balancing water resistance with the desired visual texture. Matt ceramic mosaic tiles, like those used in this project, offer good slip resistance for floors and reduce glare from bathroom lighting compared to glossy finishes. The cream and dim green tones in this apartment complement the warmth of the oak floors visible from other areas of the home. Flat roof solutions become relevant in bathroom renovation when the space is on an upper floor or beneath a roof terrace, as proper drainage and waterproofing layers protect the ceiling finishes below.
Black metal frames around bathroom mirrors, faucets, and handles echo the industrial details found in the main living space. This repetition of materials across rooms is a deliberate strategy that makes a smaller apartment feel larger and more intentional. The concrete washbasins were custom-cast, which allowed the designers to match the exact tone of the exposed ceiling concrete.
Bringing Natural Light Through the Apartment
The success of the STROM Flat renovation depends heavily on how natural light moves through the space. The large windows in the functionalist building provide abundant daylight, but the layout improvement was what allowed that light to reach the central living area. Before the renovation, interior walls likely blocked much of the light. After removing unnecessary partitions and aligning the primary living zone with the window wall, the green treetops outside become visible from the center of the apartment.
This strategy of prioritizing natural light in the layout is effective for any apartment renovation. Flat roofs and skylights design, flashing, and installation offer another route for bringing daylight into deep-plan apartments, particularly in top-floor units where roof access allows the addition of overhead glazing. Combining side windows with skylight openings can transform a previously dark interior into a well-lit living environment.
The approach demonstrated in this Prague apartment project offers practical guidance for anyone planning an open-concept renovation. By working with the existing structure rather than covering it, selecting a restrained material palette that complements original finishes, and using furniture for zoning instead of walls, it is possible to create an apartment that feels spacious, personalized, and connected to its surroundings.