The short answer
Moisture Is the Primary Culprit
That persistent musty smell often points directly to hidden moisture. Water can wick up drywall from a damp concrete slab or seep in from a leak behind baseboards. The bottom foot of a wall is especially vulnerable to spills, overwatering plants, or minor flooding that goes unnoticed.
Once wet, the drywall's paper face and gypsum core act like a sponge, holding water. In a semi-arid climate with hot dry summers and cold winters, this trapped moisture creates a stark contrast to the dry indoor air, fueling the odor. The lack of airflow at floor level prevents it from drying naturally.
How Mold Contributes to the Odor
A damp environment is ideal for mold growth, which produces microbial volatile organic compounds (mVOCs). These compounds are the source of that strong, earthy, or stale smell. You might not see visible mold immediately, as it can grow inside the wall cavity or on the back of the drywall.
The smell itself is a warning sign of a potential mold issue. If you detect a persistent odor, it's wise to investigate for hidden moisture promptly. Ignoring it can allow mold colonies to expand, which may require more extensive remediation later.
- Musty, earthy odors from microbial activity.
- Growth often hidden behind baseboards or panels.
- Spores can spread through the home's air.
- Poses a risk to indoor air quality.
- Damp cellulose (paper) is a food source.
- Requires professional assessment for safe removal.
Steps to Take When You Smell It
Your first step is to stop any active water source. Locate your main water shutoff valve. If you live in Meridian, keep your shutoff valve location written down. Then, move furniture away from the wall and pull back any carpet or flooring edges to inspect and promote drying.
Increase airflow with fans and use a dehumidifier in the room. However, if the drywall feels soft, shows staining, or the smell persists after 48 hours, the moisture is likely deep inside. At that point, the wall may need to be opened for proper drying or replacement.
When to Involve Water Damage Professionals
Local water damage pros have tools like moisture meters and thermal cameras to map the extent of wetness without destructive guessing. They can determine if drying is possible or if materials must be removed. They follow industry standards for structural drying to prevent secondary damage.
This work often involves removing baseboards and sections of drywall to dry the framing and insulation. The pros can also identify and stop the water source. If mold is found, they can contain the area and recommend a qualified mold professional for safe remediation.
- Accurate moisture mapping behind walls.
- Industrial-grade drying equipment for deep cavities.
- Assessment of structural integrity and material salvageability.
- Identification of the complete moisture pathway.
- Proper containment if mold is present.
- Documentation useful for an insurance claim.
Water damage does not wait
Every hour counts once water gets into floors and walls. One call starts the response.
Call Now (208) 537-2633Frequently asked questions
Can I just paint over the smelly drywall?
Painting over it will seal the odor and moisture inside, which will likely cause the paint to bubble and peel. The underlying mold or decay will continue. The wet material must be dried or removed first to solve the problem permanently.
Will my homeowner's insurance cover this repair?
Coverage depends on the source of the water. Sudden, accidental leaks like a burst pipe are often covered, while damage from long-term seepage or maintenance issues may not be. Policies vary, and your insurer decides what is covered. Document everything and check your policy.
How long does it take for mold to grow after water damage?
Mold can begin to grow within 24 to 48 hours on damp porous materials like drywall. The smell often appears around this time as the microbial activity increases. Acting quickly to dry the area is the best way to prevent a major mold issue.