Overview
- Heat alone does not automatically constitute a rental defect, but sustained indoor temperatures above roughly 26–28 °C may justify a Mietmangel claim.
- Tenants are advised to log temperatures each day and submit a written defect notice while continuing to pay rent under reservation to secure future claims.
- Rent reductions of up to about 20 percent can be applied only for specific days when documented temperatures exceed the guideline values.
- German courts evaluate each heat-related rent-minderung case individually, with attic flats and older buildings generally expected to tolerate higher temperatures.
- Renters may install standalone monoblock air-conditioning units without landlord consent, but any fixed installations or structural alterations require landlord and co-owner approval.