Found Mould in Your German Apartment? Here's Exactly What to Do — Step by Step
If you've found mould (Schimmel) in your apartment in Germany, the process for dealing with it involves documenting the problem, notifying your Hausverwaltung, requesting a professional inspection, and understanding your rights as a tenant under German law. This guide walks you through exactly what to do.
Step 1: Document Everything First
Before you contact your landlord or property management, gather evidence. Your documentation is your foundation—it proves you took the problem seriously from day one.
Take dated photos with scale: Photograph the mouldy areas with something for size reference (a coin, ruler, or hand). Use your phone's natural lighting. Take photos of the full wall, close-ups of the mould, and any discoloration spreading nearby. Date-stamp every photo.
Record humidity levels: Buy a digital hygrometer (€10–€15 from Amazon). Measure and record room humidity every morning and evening for at least one week. Note the room temperature too. This data is essential—Lüftungsverhalten disputes almost always turn on humidity readings.
Note ventilation habits: Document when you open windows (Stoßlüften—short bursts of complete window opening, not cracking them). Record duration. If you're ventilating correctly and humidity is still high, that's evidence of a building defect.
Why this matters: Your Hausverwaltung will immediately claim you're not ventilating enough. Having documented humidity readings and ventilation habits neutralizes that excuse before they make it.
Step 2: Monitor Before You Escalate
Patience at this stage saves months of later disputes. Monitor actively for 2–4 weeks before escalating formally.
Understand normal humidity: Comfortable indoor humidity is 40–60%. Above 65% regularly, mould risk increases significantly. Above 75%, it's almost certain without active remediation. Track your apartment's pattern.
Create a Lüftungsprotokoll: A Lüftungsprotokoll (ventilation log) documents your ventilation schedule and humidity readings. It's a simple table: date, time, humidity reading, window open (yes/no), duration. Keep it for 3–4 weeks minimum. This document carries legal weight—if you present it to your Hausverwaltung showing 45–60% humidity with proper Stoßlüften, they cannot blame you.
When is it a building defect? If you're ventilating properly (multiple times daily, 5–10 minutes per window) and humidity remains high, or if mould returns repeatedly in the same spot despite ventilation, it's a Baumangel (building defect). This is their responsibility under German law.
Step 3: Notify Your Hausverwaltung or Vermieter
Once you have evidence, notify in writing. Always written, never verbal or email alone—send it by registered mail (Einschreiben).
Write a Mängelanzeige: This is a formal defect notification. Include:
- Date and location of mould (room, wall corner, specific spot)
- First date you noticed it
- Photos attached (numbered and referenced)
- Humidity readings from your logs (attach the log)
- Description of ventilation habits
- Your request for inspection within a reasonable timeframe (typically 2 weeks)
- Statement: "This is a formal defect notification under BGB § 536."
Template language: "I am writing to notify you of a mould problem (Schimmelpilzbefall) in [room name] of my apartment at [address]. First observed on [date]. I have maintained proper ventilation (Stoßlüften daily, 5–10 minutes) and documented humidity readings of [range]%. Despite proper ventilation, the mould persists. This indicates a structural defect. I request a professional inspection within 2 weeks. Documentation attached."
Deadlines: German law requires property managers to respond within an "angemessene Frist" (reasonable timeframe). For mould, 2 weeks is standard. If they ignore you, that strengthens your legal position later.
What if they ignore you? If 2 weeks pass with no response or inspection scheduled, you may reduce your rent (Mietminderung). But be careful—mould damage typically justifies 10–20% reduction only if it's significant. Document the reduction in writing to them before executing it, and keep the amount conservative.
Step 4: When to Get an Independent Expert
If the Hausverwaltung sends their own "expert," that expert is usually paid by them. They work for property managers, not tenants. An independent expert changes everything.
Why independent inspection matters: A certified Sachverständiger (expert) produces a legally binding report. German courts give this document significant weight. It removes ambiguity—either there's a building defect or there isn't. Hard data (thermal imaging, moisture readings, air quality) replaces argument.
What our inspection covers: Thermal imaging (FLIR cameras detect hidden moisture behind walls), calibrated moisture meters, visual inspection for patterns (rising damp vs penetrating damp), ventilation assessment, and cause analysis. We produce a comprehensive report in English with photos, thermal images, readings, and recommendations.
Cost: A Feuchtigkeitsgutachten (moisture report) typically costs €450–€750 in Berlin, depending on flat size and complexity. This is your insurance policy against months of disputes.
How it helps: Armed with an independent report, your Hausverwaltung either repairs the problem or faces liability. If rent reduction is justified, your report provides legal evidence. If it escalates to a lawyer or court, your independent expert testimony is invaluable.
Step 5: The Resolution Process
Once you've documented, notified, and possibly obtained an expert report, the outcome typically follows one of three paths:
Path 1: They repair it. The Hausverwaltung identifies the cause (leaking pipe, rising damp, poor ventilation design) and fixes it. This is ideal. Timeline: 4–12 weeks depending on severity.
Path 2: Rent reduction. If repairs are delayed or mould persists, you reduce rent proportionally. Document the reduction in writing. This forces their hand—they either repair or lose rent indefinitely.
Path 3: Escalation. If unresolved, you may hire a lawyer (Anwalt) or contact a tenant protection organization (Mieterschutzbund). Your documented Lüftungsprotokoll and independent expert report are critical here.
Timeline expectations: Simple cases (poor ventilation identified and improved): 2–4 weeks. Structural repairs (rising damp, roof leaks): 8–16 weeks. Legal disputes: 3–6 months or longer. Start early to avoid disputes during your tenancy.
If you're moving out: If mould causes you to break your lease early, keep your Kaution (deposit) safe—don't let the landlord use it to cover repairs they should have made. An expert report proves they're liable, not you.
Common Mistakes Expats Make
Painting over mould: This traps moisture and spreads the problem. Don't do it. Mould must be removed, not covered.
Using only surface spray: Schimmelentferner (mould remover) spray kills surface mould but not root causes. If you use it, follow with proper ventilation and monitoring.
Not documenting: Expats often don't document early because they assume landlords are reasonable. In Germany, everything is governed by formal processes. Document from day one.
Accepting "you need to ventilate more" without checking: Many expats buy this excuse. If your humidity is 45–60% and you're ventilating daily, the problem isn't user behavior. Trust your data, not their claims.
Reducing rent without legal process: You can't just stop paying. You must notify formally first, give them time to repair, then reduce rent and document it. Otherwise, they'll sue for back rent.
FAQ: Mould in Your German Apartment
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