My garage smells musty or feels damp. Who do I call?
Usually, start with
Building moisture / water-intrusion professional
If the garage persistently smells musty or feels damp and the source is not obvious, a water-intrusion or moisture professional can evaluate moisture patterns and help identify whether water entry, humidity, or another building condition is involved.
Change course if
You can see active water entry during rain
Drainage or waterproofing expertise may be relevant when an exterior water path is observable.
The garage is very humid but no surfaces appear wet
An HVAC or building-performance professional may be relevant to evaluate ventilation, temperature, and humidity conditions.
The odor is localized around a drain, plumbing fixture, or appliance
A plumber may be relevant when the source may be plumbing-related.
Who handles what
Water intrusion / moisture
Evaluates unexplained dampness, moisture patterns, and potential water pathways.
Drainage / waterproofing
Evaluates exterior water movement and water entry through the building enclosure.
HVAC / building performance
Evaluates humidity, ventilation, and temperature conditions that can contribute to persistent dampness.
What might be happening
A musty odor or damp feeling indicates a moisture-related condition may be present, but it does not identify the source. Liquid water entry, elevated humidity, condensation, wet materials, and plumbing conditions can overlap or produce similar observations.
Useful things to notice
Where the odor or dampness is strongest
Walls, corners, stored materials, floor areas, or plumbing locations can help narrow the area a professional evaluates.
Whether weather changes it
A pattern after rain or during humid weather is useful context.
Whether materials show visible moisture effects
Staining, swelling, surface growth, peeling finishes, or damp cardboard and wood are useful to document without assuming a cause.
Before you call
Note how long the condition has been present, whether it changes with weather, and where it is strongest. Photograph any staining or visibly damp areas and avoid discarding affected materials until useful conditions have been documented.
Before you fix the visible symptom
Painting, deodorizing, or covering a damp surface can make the symptom less visible without identifying the moisture source. Establishing where the moisture is coming from first can help a professional determine the appropriate next step.
References
U.S. Environmental Protection Agency. Mold Course, Chapter 2: Moisture Problems.
U.S. Environmental Protection Agency. A Brief Guide to Mold, Moisture and Your Home.
U.S. Environmental Protection Agency. Moisture Control Guidance for Building Design, Construction and Maintenance.