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Building Health Sciences - Healthy buildings, healthy people, healthy business

Residential Crawlspaces

Residential crawlspaces are one of the most complicated, dynamic and geographically-influenced assemblies in residential construction. In addition, they are intimately associated with the indoor living environment’s performance. However the crawlspace assembly is frequently overlooked and under-estimated as a source of contaminants, moisture and pathway for cross-contamination of living spaces. The happenstance discovery of fungal contamination in the crawlspace by a pest control inspector led to the builder’s immediate response to the notification of mold. The customer service department .engaged local professionals: a mold and moisture specialty contractor to investigate, resolve and eliminate the contamination; an environmental consultant; biological laboratory to investigate and direct resolution of the homeowner’s health effect fears attributable to the fungal contamination on the wood building materials of the crawlspace assembly and, finally, its own forces to correct construction deficiencies.


Remediation had started of the first 65 homes. Costs skyrocketed as homeowners were being unnecessarily re-located for up to 35 days during remediation and final clearance. Legal action loomed on the horizon fed by unfounded health concerns, homeowner inconveniences and intrusive program protocols. The builder’s frustration escalated as did homeowner outrage.

BHS was engaged by the Builder to offer a second opinion on the program in place and quickly become deeply involved in a situation analysis and re-definition of the overall approach and program parameters. Remediation and clearance protocols were excessive. The original team was replaced entirely.

BHS was challenged by the builder to create a viable, cost-effective, manageable program. Marriage of construction expertise, ingenuity and understanding the work process, in association with physician-led oversight, public health driven parameters, individual pre-remediation risk communication along with checks and balances for remediation quelled the homeowner rebellion. Quantifiable results confirm the plan’s success. BHS’ continuous monitoring of occupied space and a full time, on-site, representative insured homeowners could safely remain in their residence (90% did) while remediation time was shortened to a five day turnaround – a 85% time reduction with no homeowner displacement. This was accomplished with sufficient forces to allow five homes per week to be remediated. Finally, the builder’s forces retrofitted and upgraded the crawlspace assembly, upon remediation completion. Over 95% of the first 65 remediated residences had to be re-done upon failing the first of four quarterly re-inspections pursuant to BHS’ quality assurance protocol.

Lessons Learned

Through BHS’ restoration protocols proper installation of new vapor barrier, cold joint caulking and removal of construction debris, integrity of the crawlspace’s contribution to the building envelope was returned. New home construction procedures were amended to prevent recurrence in new homes under construction. These would alleviate certain building material moisture control inadequacies, workmanship challenges and trade sequencing in the crawlspace. Homeowner contributions to additional crawlspace moisture were addressed through BHS-developed exterior inspection protocols shared with the homeowner. Post remediation inspections – quarterly for one year – revealed no subsequent fungal re-growth after implementation of the BHS remediation protocols.

Moreover, customer service departments cannot afford to treat a homeowner’s complaint, with a health component, as a standard warranty service call. The intensity and consequences of a health complaint transcend fixing the problem and are charged with emotion. Builders need to re-assess their understanding of the crawlspace’s potential to impact indoor air quality negatively.