Crawlspaces – A Primer.
Most houses built in the Puget Sound are constructed over a ventilated crawlspace. Basements are more common in older, urban homes. Sealed crawl spaces are typically only found on high-end, energy efficient homes.
Constructing homes with crawl spaces brings a number of benefits. Installation of HVAC ducting and plumbing lines is much easier. However, crawlspaces also bring their own set of problems. Much of these issues are due to the fact that crawlspaces operate outside the conditioned (heated) air space of the home, yet lie within the building envelope. This means that crawlspaces exist in an in-between zone where they don’t benefit from indoor heating and ventilation, but must remain cleaner than the exterior of the building.
What are the most common sources of crawl space problems in Seattle?
- Missing vapor barrier
- Poor drainage / flooding
- Broken sump pump
- Inadequate perimeter ventilation
- Rodent infestations
- Saturated framing during new construction
Example Crawlspace Mold Remediation Report
Work #: 202026
Project Background Information
- No significant mold growth observed on inspection.
- Crawlspace insulation installed within the belly of the manufactured home. Visible portions of insulation appear to be in adequate condition.
- At the time of inspection no increased moisture content was noted in the framing or subflooring.
- Standing water noted in portions of the crawlspace.
- Large amounts of standing water (up to 6” deep) was noted below the vapor barrier. The foundation drainage, sump system, and crawlspace grading must be addressed to prevent future water intrusion.
- No obvious plumbing leaks were observed on inspection of the crawl space. Environix is not a professional plumbing contractor and cannot guarantee the condition of any plumbing.
- Intact- Vapor barrier is intact and provides adequate coverage to all soil.
- Current ventilation is adequate to exhaust normal amounts of humidity.
- The HVAC ducting along the back side of the home is not adequately insulated allow excessive heat loss through ducting walls.
- All HVAC ducting in unconditioned space must be well insulated.
- The flexible crossover duct appears to be laying in standing water and should be replaced. This ducting should be replaced with rigid metal ducting, hung above the ground, sealed, and insulated.
Trash and Debris:
- The crawlspace is currently free from excessive amounts of trash and construction debris.