How much does balcony renovation cost per square metre?
Balcony renovation costs range from €50 to over €1,000 (about £43 to over £850) per m², depending on the scope of the work. A reliable estimate can be prepared once the balcony's size, construction, condition and proposed materials are known. Replacing only the floor covering on a sound, structurally adequate substrate often costs around €50 to €100 (about £43 to £85) per m²; new waterproofing with properly formed junctions is typically €150 to €400 (about £130 to £340) per m². A full renovation involving concrete repair and a new build-up can reach €1,000 or more (about £850 or more) per m².
The work required depends on the existing condition. It may include removing and disposing of the existing floor covering, exposing and inspecting the supporting structure, repairing damaged concrete and corroded reinforcement, forming or correcting a fall of at least 1.5%, installing waterproofing at door and wall junctions, addressing the thermal bridge created by a cantilevered slab, replacing the balustrade so that it meets guarding requirements, laying a new floor covering, and finishing or cladding the walls. The largest single cost often only becomes apparent once the old floor covering has been removed.
On cantilevered reinforced-concrete slabs, water can enter through cracks and defective junctions. Carbonation and freeze-thaw cycles can then lead to reinforcement corrosion and concrete spalling. Exposed reinforcement must be cleaned of rust and passivated, and the concrete reprofiled, before waterproofing can be applied. Where there are cracks, visible damage to the reinforcement or a planned increase in build-up height, the balcony should be assessed beforehand by a specialist contractor or structural engineer.
The balcony's performance also depends on an adequate fall, effective drainage and suitable upstand heights. Waterproofing should be turned up at door thresholds and adjoining walls in accordance with DIN 18531, and should be crack-bridging so that fine cracks in the concrete beneath cannot propagate into it. The benefit of additional insulation depends on how the balcony is connected to the building. Freestanding timber or metal balconies on their own supports are thermally separate from the building and do not require insulation; a continuous concrete slab forms a thermal bridge and can usually only be thermally broken as part of more extensive building work.
The choice of floor covering affects both the work involved and later maintenance. Ceramic tiles can spall in frost, timber needs regular maintenance and may rot, and WPC can become very hot and distort. WARCO rubber tiles made from PU-bound rubber granules are weather-resistant and suitable as a balcony covering; they are free-draining and can be laid on the prepared balcony without adhesive.
The total cost includes the materials, installation, disposal, any concrete repair and future maintenance. Considered together, these items give a reliable basis for long-term planning.