Balcony renovation: Why balcony renovation and insulation must always be considered together

Balconies as an energy weak point on the building envelope

The biggest physical problem area on the balcony is the continuous reinforced concrete slab: it penetrates the insulated façade and acts like a cooling fin. The result is a kind of counterproductive energy exchange with heat loss from the building envelope. Reinforced concrete (2.3 λ ) conducts heat around 65 times more than modern insulation materials (XPS insulation material 0.035 λ), which literally allows the heating energy to flow outside in winter and presses the cold against the house wall.

The energy losses caused by uninsulated balcony slabs are only one side of the problem. The other is often more serious in terms of building physics, because where heat escapes unhindered, cold surfaces are created on the room side. These act as thermal bridges in the interior wall, particularly at the connection points between the ceiling, wall and balcony slab.

Condensation as a cause of mold damage

What follows is a typical domino effect in building physics: the cold causes the surface temperature of certain building components to fall below the dew point temperature of the room air. This is not constant, but depends on the temperature and relative humidity. If the temperature falls below the dew point, the water vapor contained in the air begins to condense - condensation forms on the cold surfaces.

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This moisture creates ideal conditions for mould, which not only affects health, but also endangers the fabric of the building and the value of the property in the long term. Particularly insidious: such damage often occurs in secret - behind furniture or curtains, for example - and remains unnoticed for a long time. Once the mold has penetrated deep into the plaster or plasterboard, it becomes time-consuming and expensive to remove.

It is not only the harmful mold infestation that is affecting the property. Layers of plaster and paint are also peeling off, the reinforcement (metal struts) in the concrete is starting to rust and cracks are appearing. The result is a progressive weakening of the load-bearing structure, which can lead to serious structural damage in the long term and necessitate costly concrete repairs.

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In short, an unrenovated balcony connection not only jeopardizes energy efficiency, but also the physical quality of the building and the health of the occupants.

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The effective balcony renovation

For a successful balcony renovation, basic structural requirements must first be met. The load-bearing capacity of the existing balcony slab must be sufficient to support the additional weight of the new floor structure including insulation. The substrate for bonding must also be clean, dry and load-bearing.

Especially in existing buildings, many balconies do not meet today's building physics requirements. A thorough analysis of the existing building is therefore essential. This includes checking the statics, gradient and existing waterproofing. Concrete restoration is often necessary before the actual insulation measure, e.g. by reprofiling damaged areas or protecting exposed reinforcement against corrosion.

Flank insulation in existing buildings

In existing buildings, so-called flank insulation has proven particularly effective: Here, the balcony slab is clad with insulation material on the top, bottom and front sides to effectively minimize thermal bridges. A seamless connection to adjacent wall and ceiling surfaces is crucial to ensure that there are no weak transitions in terms of energy efficiency.

The choice of insulation materials depends on the respective load: pressure-resistant, water-resistant materials such as XPS or PUR are particularly suitable for the top-side insulation in the floor structure. Vacuum insulation panels (VIPs) are often used in narrow reveals where space is tight - although they are more expensive, they enable very thin insulation layers with high performance.

Eligible and economical with a system

Balcony insulation is part of the Federal Subsidy for Efficient Buildings (BEG) and can be subsidized by BAFA for individual measures or financed by KfW as part of an efficiency house refurbishment. In short, you enhance the economic and visual value of a property with a refurbishment, reduce energy consumption and have this return on investment financed through the targeted use of subsidies. A clever move! However, it is stipulated that an energy efficiency expert must be involved in the process in order to legitimize the subsidies. Refurbishment measures must be accompanied and documented by the expert, who acts as a kind of supervisory body. Our team of energy efficiency experts will be happy to help you and is available for a non-binding initial consultation.

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Conclusion: Small area with great leverage

The renovation of balcony connections is often the decisive detail that determines the energy quality of a building. The thermal separation between the balcony and the building is important. With well-planned insulation, professional execution and well thought-out integration into the overall concept as part of energy-efficient façade insulation, considerable energy losses can be stopped, damage avoided and state subsidies secured, even with structures as inconspicuous as a balcony. The only important thing is to have a contact person who is able to find a holistic solution that makes economic sense for the owner.

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Let's talk about your balcony project for apartment buildings or residential and commercial buildings without obligation.

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