In its judgment of 17 July 2026 (V ZR 162/25, case no.), the Bundesgerichtshof (BGH, Federal Court of Justice) considered the conditions under which a condominium owner may demand that the community of condominium owners (Gemeinschaft der Wohnungseigentümer – GdWE) permit the installation of a split air-conditioning unit on the owner’s balcony. The decision focuses on the requirements governing structural alterations to common property under § 20(3) WEG (German Condominium Act) and on the question of when such a measure materially impairs the legal rights of other condominium owners. In its decision, the BGH strengthens the rights of condominium owners seeking to carry out construction work and clarifies that mere concerns about possible noise and other emissions generally do not preclude permission.
Installation of a Split Air-Conditioning Unit on a Balcony
The claimants were members of a community of condominium owners. They intended to have a split air-conditioning unit installed on the balcony belonging to their condominium. With such a unit, the actual cooling technology is located inside the condominium, while an outdoor unit is installed on the balcony. A conduit is required to connect the two units, necessitating drilling through the external façade.
Approval of the Community of Condominium Owners Required
Because the external façade forms part of the common property, the planned installation required permission by means of a resolution of the community of condominium owners pursuant to § 20(1) WEG.
At the owners’ meeting, the claimants therefore submitted a corresponding proposed resolution. However, it failed to secure a majority. The other condominium owners were particularly concerned about:
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disturbance caused by noise from the air-conditioning unit,
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the waste heat generated,
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possible condensate leakage,
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effects on the visual appearance of the residential complex, and
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a possible reduction in the value of neighbouring condominiums.
Permission Resolution Replaced by Court Decision
After the application had been rejected, the claimants brought an action for judicial replacement of the resolution pursuant to § 44(1), sentence 2 WEG before the Amtsgericht Pankow (Pankow Local Court; 7 C 24/24 WEG, case no.). The court initially dismissed the action. On appeal by the claimants, the Landgericht Berlin II (Berlin II Regional Court; 56 S 40/24 WEG, case no.) reversed the decision at first instance and replaced the requested permission resolution with a court decision. In doing so, it imposed specific requirements concerning the design and operation of the split air-conditioning unit.
The defendant community of condominium owners challenged this decision before the Bundesgerichtshof by means of an appeal on points of law for which the Landgericht had granted leave.
Decision of the Bundesgerichtshof
The Bundesgerichtshof dismissed the defendant community’s appeal on points of law, thereby upholding the decision of the Landgericht Berlin II. According to the BGH, condominium owners may generally demand that the installation of a split air-conditioning unit on their balcony be permitted by resolution. This also applies where the installation requires drilling through the external façade and thus interference with the common property.
The BGH first clarified that the installation of the air-conditioning unit constitutes a structural alteration to the common property within the meaning of § 20(1) WEG. Because the air-conditioning system is not one of the privileged structural alterations under § 20(2) WEG, any entitlement to permission is governed by § 20(3) WEG.
Under that provision, a condominium owner may demand a structural alteration if all condominium owners whose rights are impaired by the measure beyond the extent unavoidable in orderly communal living consent to it.
In this context, the BGH clarified the concept of a legally material impairment. Such an impairment exists where, according to generally accepted standards, a condominium owner can reasonably consider themselves adversely affected. In this assessment, the property rights protected by Art. 14 GG (German Basic Law) of both the condominium owners wishing to carry out the work and those who do not consent must be weighed against each other.
In the specific case, this meant that the anticipated effects of the air-conditioning unit did not constitute sufficient grounds for refusing permission.
Reasoning of the Bundesgerichtshof
The BGH’s observations regarding potential noise emissions are particularly significant. The defendant community had argued, in particular, that the subsequent operation of the air-conditioning unit could cause substantial noise disturbance.
The BGH did not accept this argument. As a general rule, the noise expected to arise from the subsequent use of a split air-conditioning unit does not preclude an entitlement to permission under § 20(3) WEG. The position is different only if, at the time permission is granted, it is already certain that the anticipated emissions will result in a legally material impairment of other condominium owners.
No Concerns Regarding Noise Disturbance
That was not the case here. Split air-conditioning units approved for the German market may generally be assumed to be capable of complying with the applicable noise-control requirements. Mere concerns about potentially disruptive noise are therefore insufficient to prevent the installation.
Another decisive factor is the temporal distinction between the structural alteration and the subsequent use of the unit. Permission to install the unit does not mean that the condominium owner concerned may subsequently operate it without restriction and without regard for the interests of their neighbours.
If unreasonable noise emissions actually arise after installation, the affected condominium owners may still assert the corresponding claims for injunctive relief. Where appropriate, the community may also subsequently adopt rules governing use. It is therefore unnecessary to settle conclusively every conceivable conflict regarding use as part of the permission resolution.
The relevant benchmarks for determining reasonableness are the guideline values under the TA Lärm (German Technical Instructions on Noise Abatement). The BGH assumes that the unit approved for the domestic market is generally capable of complying with the TA Lärm and that the nearest bedroom window is several metres away from the claimants’ balcony. If operation nevertheless breaches these guideline values, the neighbours’ right to seek legal protection remains unaffected.
According to the BGH, the same applies to the anticipated waste heat and any possible condensate leakage. Any unacceptable impairment in this respect may likewise be challenged subsequently. Under § 21(1) WEG, the condominium owner wishing to carry out the work must bear any consequential costs.
BGH Finds No Loss in Value of Neighbouring Condominiums
The community’s other objections likewise failed to persuade the BGH. No material adverse effect on the overall appearance of the building had been demonstrated. The outdoor unit was to be installed on the balcony and additionally screened from view. Nor was there any specific evidence that the installation could reduce the rental or sale value of neighbouring condominiums.
Finally, the BGH did not consider the absence of express requirements for a prior structural calculation to be problematic. The court-ordered permission already stipulated that the installation had to be carried out by licensed specialist contractors in compliance with the statutory provisions and generally accepted engineering standards. Any necessary structural calculations were therefore adequately covered.
Conclusion and Practical Significance of the Judgment
The BGH judgment of 17 July 2026 strengthens the position of individual condominium owners vis-à-vis their community where they seek to make a structural alteration to the common property.
The decision makes clear that the mere possibility of future impairment is insufficient to reject an entitlement to permission under § 20(3) WEG. Instead, there must be specific circumstances on the basis of which other condominium owners could reasonably consider themselves adversely affected according to generally accepted standards.
Particular emphasis should be placed on the distinction between the structural installation of an air-conditioning system and its subsequent operation. The community may not refuse the installation solely because it fears possible future conflicts over its use. Any unreasonable emissions that actually occur may still be challenged through legal action after the event.
However, the judgment does not establish an unrestricted right to install an air-conditioning system. The specific structural and local circumstances remain decisive. In particular, material adverse effects on the building’s appearance or unreasonable emissions that are already certain to occur may still preclude permission.
Overall, with this decision, the BGH continues the approach under condominium law of giving greater consideration to individual interests in modernisation and use, without losing sight of the legitimate property interests of the other condominium owners.
MTR Legal Rechtsanwälte advises condominium owners and communities of condominium owners on legal matters; further information is available under legal advice on real estate law.
