Damp & humidity at home in Luxembourg : the complete 2026 guide

In Luxembourg, many homes show lasting signs of humidity : black mould patches, condensation on windows, saltpetre, blistered paint or a musty smell. Before treating, you must identify the exact type of humidity, otherwise the works will not last. This guide covers the 8 cases the sworn experts mandated by HUMINUS encounter on site, with a full methodology for an accurate diagnosis.

Why is humidity an issue in Luxembourg ?

Luxembourg's climate combines damp winters (outdoor humidity above 85 % from November to February), driving rain on south-west facing facades and increasingly airtight homes. The result : water vapour produced by occupants (about 12 litres a day for a family of four) no longer escapes naturally.

Without effective ventilation, this humidity condenses on cold surfaces, saturates materials and ends up favouring mould. Long-term, humidity damages the building, lowers property value and can affect respiratory health.

The 8 humidity types diagnosed in Luxembourg

1. Rising damp : water rises from the ground via capillary action. Signature : horizontal stain at 1–1.5 m, powdery saltpetre.
2. Condensation : indoor vapour deposits on cold surfaces. Signature : morning droplets, black corners, fogged windows.
3. Lateral infiltration : water enters through a leaky facade or roof. Signature : sharp localised stain after rain.
4. Driving rain : wind-driven rain soaks an exposed facade. Signature : diffuse patches, slow inward spread.
5. Hygroscopic humidity : salts trapped in masonry attract air moisture. Signature : recurs after every repaint.
6. Thermal bridge : insulation discontinuity creates a cold spot. Signature : geometric stain (square, line) at the same place every winter.
7. Ventilation / MVHR defect : blocked vents, insufficient airflow. Signature : general musty smell, heavy air, blackened vents.
8. Accidental water damage : leak, burst pipe, overflow. Signature : sudden onset, sharp outline, stagnant water smell.

Sworn-expert methodology coordinated by HUMINUS

1. First contact : phone qualification of symptoms, age, configuration.
2. On-site visit : room-by-room visual inspection, before-photos.
3. Technical measurements : air RH, surface RH, infrared thermography, calcium carbide method (CM).
4. Analysis : cross-checking measurements, identifying one of the 8 types.
5. Expert report : signed PDF, photos, plans, prioritised recommendations, independent cost estimate.

How much does a humidity assessment cost in Luxembourg in 2026 ?

HUMINUS, your sworn humidity expert in Luxembourg

HUMINUS is the only Luxembourg provider combining professional MVHR maintenance with independent sworn humidity assessment. Our report is admissible by insurers and courts. Nationwide service, quote within 24 working hours.