Crawl space inspection — where the moisture starts.
Continuous vapor barrier, sealed-crawl protocol, joist condition, encapsulation feasibility, and sump performance — documented with moisture meter and thermal sweep across older Round Lake, Cedar Forest, and Mitchell-Lake-area builds.
Lake-adjacent moisture, mid-century crawls, vented-not-conditioned legacy.
A meaningful subset of Eden Prairie homes — older Round Lake cottages, Cedar Forest builds, additions across Mitchell Lake and Bryant Lake parcels — sit on crawl space rather than full basement. Most were built vented; in our humid summer that vent strategy delivers wetter air than the soil produces. The result is decade-on-decade moisture loading at the rim joist, surface mold on framing, rust at hangers, and compressed fiberglass batts that lose their R-value. The fix is rarely demolition — it's a properly sealed and conditioned crawl with a continuous vapor barrier and dedicated dehumidification.
What we map under the floor.
Six recurring failure modes in Eden Prairie crawl space construction — every one logged with moisture meter readings and thermal imagery.
Discontinuous vapor barrier
Construction-grade poly torn at every penetration, seams unsealed, no wall lap. Soil moisture drives unimpeded into framing.
Rim-joist condensation
Cold rim joist meets warm humid crawl air. Surface mold and elevated wood moisture at every bay.
Joist decay or split
Localized rot at plumbing leak, water-line drip, or grade-bearing condition. Sister or replace before finishing above.
Drooped fiberglass insulation
Moisture-loaded batts pulling free of joist bays. Effective R-value collapses; the batt now wicks moisture rather than insulating.
Sump pump fault
Float stuck, check valve failed, or discharge frozen. Water rises into the crawl. Documented with cycle test and discharge trace.
Foundation efflorescence
White mineral deposit on block foundation indicates active moisture migration. Map and monitor; usually a drainage and grading fix.
Vented vs conditioned — what fits your house.
For Minnesota climate the conditioned approach almost always outperforms the vented approach. The right path depends on existing condition, finished space above, and access for retrofit.
| Component | Vented (legacy) | Conditioned (sealed) | Recommendation |
|---|---|---|---|
| Vapor barrier | None or 6 mil | 10–20 mil reinforced, sealed seams, wall lap | Conditioned |
| Perimeter vents | Open | Sealed and insulated | Conditioned |
| Rim joist | Fiberglass batt | Spray foam or sealed rigid | Conditioned |
| Humidity control | Outdoor air | Dedicated dehumidifier or HVAC tie-in | Conditioned |
| Wall insulation | None | Continuous rigid at perimeter | Conditioned |
| Drainage / sump | Often missing | Perimeter drain to sealed sump basin | Required at lake-adjacent |
Three steps. Every joist bay accounted for.
Access & baseline
Hatch or perimeter access. Baseline temperature, RH, and ambient water-content reading. Vapor-barrier coverage photographed end-to-end.
Joist-by-joist with moisture meter
Wood-moisture readings at every joist bay, rim joist, sill, and subfloor near plumbing. Thermal sweep at the rim. Insulation condition and connection-hardware corrosion logged.
Encapsulation feasibility scope
Photographs, moisture map, joist condition matrix, and a feasibility-grade conversion scope a contractor can quote against. Sump cycle test and discharge documented where applicable.
Crawl-space home under contract? Get the moisture map before the offer.
Same-evening report. Joist bay matrix, vapor barrier audit, encapsulation scope.