Allergy Alert for Champaign, Illinois

CASE HISTORY: Crawl space work

 

Introduction Dr. Michael H. has a thriving practice in an east central Illinois community. Dr. H. purchased the current 6,000 sq ft building new approximately 20 years ago.

Dr. H. approached us about strong musty odors infiltrating into the occupied area of his building. A faint musty odor had been observed before, but the origin off the odor was unknown. Recent work in his crawl space by a local service contractor resulted in strong musty odors permeating throughout the entire building. Due to the nature of his practice, the situation became urgent quickly, but at last the source of the odor was known.

There were two sump pumps located in the crawl space with plastic sheeting on the crawl space floor overlay with 2-3 inches of pea gravel. The crawl space was damp and very humid with a strong musty odor.

 

Initial Problem and Complaint
  • Strong musty odor emanating from the crawl space
             

  

 

                                                                                                      

Inspection Results
  • Damp, very humid crawl space
  • Relative humidity excessive at 82% (should be  <60%)
  • Condensation dripping down the crawl space walls
  • Insulation wet from condensation on band joists
  • Early stage mold growth and wood decay
  • Water pooled on one end of crawl space
  • Plastic sheeting below pea gravel trapping water
  • One sump pump on each end of building ineffective at keeping crawl space dry
  • Musty odor originating from mold in dirt and pea gravel
     

    

                    Condensation forming on crawl space walls                                

 

                        Unsealed dirt crawl space (Left) and moisture intrusion along crawl space wall (Right)

 

 

When wet insulation in bandbox area was removed (A), saturated wood components (B), dripping condensation (C), and early stage wood-rot and mold growth were revealed.

 

Corrective Measures
  • Remove wet fiberglass insulation from band joists
  • Install drainage tile to channel incoming water into sump pumps
  • Apply 2 inches polyurethane foam insulation to band box area (thermal and air barrier)
  • Encapsulate crawl space 12 mil scrim reinforced vapor barrier
  • Install two commercial grade dehumidifiers

          

 

Band joists coated with a polyurethane foam insulation (left and right), and sealed crawl space vent (right).

                   

 

Before and after pictures of crawl space encapsulation.

 

Sump pump drainage outside building. Trench dug for PVC drain pipe, and trench filled in.

 

 

 

Encapsulated crawl space with dehumidifier to maintain RH <60% (left).

 

 

 

 

 

 

 

Clean and dry environment after encapsulation in crawl space.

Conclusions
  • New drainage tile effectively channeling incoming water to sump pump
  • No more standing water
  • Encapsulation effectively keeping mold, odors, and moisture out of crawl space
  • Musty odor eliminated and building smelling fresh and clean
  • Relative humidity decreased to <60%