The Most Common Household Molds in Spokane County and Coeur d’Alene (And What They Mean for Your Home)
If you live in Spokane County, Post Falls, Rathdrum, or the greater Coeur d’Alene area, you already know how our climate creates the perfect recipe for mold growth. Between snowy winters, wet springs, and humid summers, homes in the Inland Northwest often experience moisture issues, particularly in crawl spaces, attics, basements, and bathrooms.
Understanding the most common molds found in homes can help you identify problems early and protect your property from costly damage. Below is a breakdown of the four molds we most often find during mold inspections in Spokane and Coeur d’Alene homes, along with what makes each unique.
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1. Stachybotrys Chartarum (True Black Mold)
The most dangerous and most misunderstood mold in Inland Northwest homes.
Appearance:
Dark greenish-black or deep jet black
Slimy or wet when active; may turn powdery when it dries
Grows in thick circular or irregular patches
Common on cellulose-rich materials: drywall paper, OSB, wood, insulation backing, and cardboard—materials found everywhere in homes across Spokane and North Idaho
Smell:
Strong musty or earthy odor that often smells like wet soil or decaying leaves
Growth Conditions:
Requires constant moisture for 7–10+ days
Thrives in areas with slow leaks or chronic dampness
Less likely to grow on surfaces that dry quickly
Where we find it most often:
Crawlspaces with standing water, basements with seepage, roof leaks in Spokane’s older neighborhoods, bathrooms without ventilation, and flooded homes in Post Falls and Coeur d’Alene.
NEED A MOLD INSPECTION/REMEDIATION? REACH OUT TO US HERE.
2. Cladosporium
One of the most common molds found in Spokane homes, especially in drier, cooler spaces.
Appearance:
Black, green, or brown
Velvety, suede-like, or powdery
Common on painted walls, HVAC vents, carpets, and fabrics
Key Difference:
Cladosporium doesn’t need constant moisture the way Stachybotrys does. It grows even in cooler, semi-dry conditions—making it a frequent guest in Inland Northwest basements and attics.
Where we find it most:
HVAC systems throughout Spokane Valley, closets and carpets in older Coeur d’Alene houses, and bathroom surfaces with poor airflow.
NEED A MOLD INSPECTION/REMEDIATION? REACH OUT TO US HERE.
3. Aspergillus Niger
Fast-spreading and common in homes with airflow or HVAC issues.
Appearance:
Black or dark gray
Powdery, dusty, or fuzzy texture
Grows quickly on damp walls, food, or inside HVAC systems
Key Difference:
Unlike Stachybotrys, Aspergillus is more powdery and lightweight, spreading easily through airflow. In homes across Spokane County with older ducting or dirty filters, it’s extremely common.
Where we find it most:
HVAC systems, around furnace rooms, in damp basements, and on walls near moisture intrusion points.
NEED A MOLD INSPECTION/REMEDIATION? REACH OUT TO US HERE.
4. Alternaria
Very common around windows, showers, and anywhere condensation appears.
Appearance:
Dark brown to black
Woolly, furry, or soft texture
Often appears in streaks or lines instead of thick patches
Key Difference:
Alternaria grows in areas with intermittent moisture, not necessarily constant dampness. This makes it extremely common in homes near the Spokane River, Hayden Lake, and Lake Coeur d’Alene, where humidity fluctuates.
Where we find it most:
Window sills, showers, behind kitchen sinks, under bathroom cabinets, and in laundry rooms.
NEED A MOLD INSPECTION/REMEDIATION? REACH OUT TO US HERE.
Why Mold Is So Common in Spokane & Coeur d’Alene Homes
Homes in the Inland Northwest experience:
Heavy winter snow → melting moisture
Wet springs → saturation and flooding
High summer humidity → ideal mold conditions
Cold winters → condensation buildup
Older homes → poor ventilation
Crawlspaces with minimal insulation → dampness
These environmental conditions—combined with common aging home systems—create perfect mold growth environments year-round.
NEED A MOLD INSPECTION/REMEDIATION? REACH OUT TO US HERE.
Concerned You Might Have One of These Molds?
If you notice musty smells, dark patches on walls, condensation on windows, or discoloration around vents, it’s time for a professional mold inspection. Many Spokane and Coeur d’Alene homeowners don’t realize mold is present until it becomes severe, and by then, repairs can be costly.
Our certified team provides:
Mold inspection and testing
Emergency mold response
Mold remediation and removal
Water damage restoration
Crawlspace and attic mold cleanup
Preventative treatments for long-term protection
NEED A MOLD INSPECTION/REMEDIATION? REACH OUT TO US HERE.
Serving:
Spokane County • Liberty Lake • Spokane Valley • Airway Heights • Cheney • Mead • Deer Park • Post Falls • Rathdrum • Hayden • Coeur d’Alene • Athol and surrounding areas
