How much does balcony renovation cost per square metre?
The cost to renovate a balcony ranges from around €50 (about £43) to more than €1,000 (about £850) per square metre, depending on the scope of the work. A more precise cost estimate can only be provided once the balcony’s size, construction, condition and the building materials to be used are known.
Where only the covering is replaced on a sound, intact substrate, costs are often around €50 to €100 (about £43 to £85) per square metre. If new waterproofing with properly detailed junctions is required, costs are more likely to be €150 to €400 (about £130 to £340) per square metre. A full renovation involving repairs to the concrete structure and a new build-up can reach €1,000 (about £850) per square metre or more. Depending on the starting condition, work may include removing and disposing of the existing covering; exposing and assessing the supporting structure; repairing damaged concrete surfaces and corroded reinforcement; creating or correcting a fall of at least 1.5%; installing waterproofing with proper connections to doors and walls; measures to address the thermal bridge of a cantilevered slab where needed; renewing the balustrade in line with fall-protection requirements; laying a new covering; and finishing or cladding the walls.
The largest and often underestimated cost may only become apparent after the existing covering has been removed. In cantilevered reinforced-concrete slabs, water can enter through cracks and leaking junctions. Carbonation and freeze-thaw cycles can then cause reinforcement corrosion and concrete spalling. Exposed reinforcement steel must be cleaned of rust and passivated, and the damaged concrete section must then be reinstated before the balcony can be waterproofed.
If there are cracks, visible damage to the reinforcement or plans to increase the build-up height, the condition should be assessed in advance by a specialist contractor or structural engineer. From a building-performance perspective, an adequate fall, effective drainage and the required upstand heights are critical. Under DIN 18531, the waterproofing is turned up at door thresholds and adjoining walls. It should bridge cracks so that hairline cracks in the concrete do not pass through it.
Whether additional insulation is worthwhile depends on how the balcony is connected to the building. Independently supported timber or metal balconies stand on their own supports and are already thermally separated from the building, so they do not require insulation. A continuous concrete slab acts as a thermal bridge and can usually only be fully separated from the building during wider alteration work. The choice of covering also affects the work involved and later maintenance: ceramic tiles can spall in frost, timber requires substantial maintenance and can rot, while WPC can become very hot and distort. Weather-resistant WARCO rubber tiles made from PU-bound rubber granules are suitable as a balcony covering; they have a water-permeable structure that allows drainage and are laid on the prepared balcony without bonding.
Total costs include purchase and installation, disposal, any concrete repair, and later maintenance and servicing costs. This provides a reliable basis for long-term planning.