If you've lived in Boise for any length of time, you know we're not like other cities. We're a high desert that floods its land with irrigation water half the year. This creates a unique "wet/dry" cycle that's absolute murder on crawl spaces—and most national contractors don't understand it.
📷 Photo: Moisture damage in Boise crawl space
The Boise Crawl Space Problem
Most crawl space advice is written for humid climates like the Southeast. Boise is different:
- Irrigation Season (April-October): Water table rises dramatically. Standing water appears in previously dry crawl spaces.
- Dry Season (November-March): Water table drops. Soil shrinks. Humidity drops to near-desert levels.
This cycle creates unique problems that don't exist in consistently wet or consistently dry climates.
Why "Traditional" Vented Crawl Spaces Fail Here
Building codes historically required vents in crawl spaces, thinking outside air would dry them out. In Boise, this backfires spectacularly:
Summer Condensation Problem
In summer, outdoor air is 90°F+ and relatively humid (monsoon moisture from the Southwest). Your crawl space is 60-65°F—cooled by the earth. When hot, moist air enters the cool crawl space, it condenses.
Result: Water droplets on cold surfaces (pipes, floor joists, ductwork). Mold grows within 48-72 hours.
Winter Freezing Problem
In winter, vents let freezing air into your crawl space. Now you have:
- Frozen pipes (burst pipe risk)
- Cold floors above (comfort issues)
- Increased heating bills (you're heating the ground)
The Irrigation Factor
What makes Boise truly unique is our canal system. When irrigation starts in April:
- Fields flood across the valley
- Water percolates into the aquifer
- Water table rises by 3-8 feet in many areas
- Suddenly, crawl spaces that were dry all winter have standing water
This happens fast. We get calls every April from panicked homeowners: "I never had water before!"
Signs Your Crawl Space Is Failing
- Musty smell in the house: Air rises from the crawl space into your living areas (the "stack effect")
- Bouncy or cold floors: Moisture weakens joists; poor insulation = cold feet
- High humidity indoors: Especially in summer. Crawl space moisture migrates upward
- Visible mold or mildew: On furniture, in closets, or on lower walls
- Pest activity: Rodents, spiders, and insects love dark, damp spaces
- HVAC problems: Condensation on ductwork, reduced efficiency
The Solution: Sealed (Encapsulated) Crawl Space
Building science has evolved. The modern solution for Boise crawl spaces is encapsulation—sealing the crawl space off from outside air and the ground.
What Encapsulation Includes
- Drainage first: If water intrusion exists, we install a French drain and sump pump
- Heavy vapor barrier: 20-mil reinforced liner covers floor and walls
- Vent sealing: All foundation vents closed permanently
- Wall insulation: Spray foam or rigid board on walls (not between joists)
- Dehumidification: Commercial-grade dehumidifier maintains 50% RH year-round
Results
- Stable humidity (no seasonal swings)
- Warmer floors in winter
- Lower HVAC bills
- No more musty smell
- Protected structure (no rot or mold)
Free Crawl Space Inspection
Not sure what's happening under your house? We'll crawl in, assess the conditions, and show you photos of what we find—no charge.