I.        GENERAL

With the ever-increasing concerns over indoor air quality, building owners and tenants are becoming increasingly aware of mold and mildew problems and related consequences.  Insurance companies are now excluding mold and mildew remediation from hazard insurance and attorneys are pursing exposure litigation. 

In real estate negotiations for existing facility to be reused by our clients, it is preferable to require the Seller, Landlord, or Developer to deliver a “clean” facility, free of mold and mildew, as evidenced by an investigative or remediation report from a Certified Testing Agency.

If the real estate negotiations excluded this provision CASCO recommends the Client retain a Certified Testing Agency to investigate, and if required, remove all mold and mildew prior to the start of remodeling operations.

In addition, the Contractor should be charged with controlling factors that stimulate mold growth and with protecting components during construction and  the responsibility of retaining a qualified and licensed specialty company to remedy any and all mold or mildew discovered during (or within the warranty period after construction). 

Attached to this Bulletin is a set of drawing notes which CASCO recommends be placed on the drawings for all projects, new and remodel.  CASCO also recommends these notes, or a customized version, be added to all Client prototype documents.

After construction is completed, the Client’s maintenance program should include proactive procedures to prevent moisture intrusion and other conditions favorable to mold growth.  Mold is a naturally occurring environmental condition that cannot be entirely eliminated; however, with good maintenance practices the hazards can be minimized.


Air conditioning systems which are initially free from mold and mildew can develop chronic air quality problems with improper and inadequate maintenance procedures.  Owners and Tenants responsible for HVAC maintenance should insure that mold and mildew concerns are properly addressed by their maintenance program.

Although much has been published regarding HVAC criteria and indoor air quality, there are currently no Code provisions related to humidity specifically for the prevention of mold and mildew.

Air conditioning systems improve human comfort by reducing temperature and humidity.  However, most ordinary air conditioning systems are controlled only by thermostats  . . . and thermostats control only temperature.  They do NOT directly control humidity.

While air conditioning tonnage selection takes humidity into account, it is usually a secondary factor.  The Engineer’s ability to select air conditioning equipment to satisfy both temperature and humidity criteria under all possible combinations of occupancy and cooling load is virtually impossible with most ordinary air conditioning equipment.  Practical limitations on zoning control also contribute to humidity variations.

Special HVAC equipment is available which can directly control both temperature and humidity.  However, such systems have higher initial costs and greater operating costs.  If you feel your facilities require such control, or if you wish further guidance, contact your Engineer . . . . .  or call CASCO.   


  1. The following requirements shall apply to all new and remodel construction projects.
  2. In the event the Contractor discovers, at any time during demolition, construction, and/or remodeling operations, existing conditions that could include the presence of mold and/or mildew, the Contractor shall immediately notify the Owner’s Representative and the Architect/Engineer of Record, in writing, of the concerns and/or suspicions.
  3. Concurrently, the Contractor shall be responsible to retain a mold and mildew Certified Testing Agency to perform an investigation and testing as required to evaluate the nature and extent of the problem.  If the Testing Agency confirms hazards, the Contractor shall be responsible to obtain a minimum of two (2) bids from companies qualified and licensed to perform all necessary remediation work, complying with all local, State, and Federal environmental regulations, codes, and statutes.       
  4. Once discovery or suspicion of mold and/or mildew is made, the Contractor shall take all reasonable and practical precautions to protect all construction personnel and the public from exposure to mold and/or mildew, and such precautions shall remain in place until such time as the Owner or Health Authority directs otherwise.  Construction operations shall not be stopped or curtailed, except in the area of mold/mildew concern, due to these required precautions.
  5. The Contractor shall make all reasonable efforts to avoid conditions favorable to the development of mold and mildew, especially in voids which will be concealed and not ventilated. In all cases, interior spaces and interior finished construction shall be maintained in dry and well-ventilated conditions.
  6. The Contractor shall comply with Federal environmental and OHSA regulations and all local and State Health Department requirements and recommendations regarding mold and mildew.
  7. All penetrations shall be sealed water-tight to prevent moisture migration from entering the building or wall cavities.
  8. All condensate drain pans shall be cleaned and kept free from debris until and when the facility is turned over to the Owner or tenant.  Insure positive drainage at all drain pans.  Insure that all “cold” surfaces are insulated and covered with a fully sealed and continuous vapor barrier.  (“Cold” surfaces include, but are not limited to, domestic cold water piping, chilled water piping, interior rain leaders, outdoor air intakes, and ductwork carrying air conditioned supply air.)
  9. Insure that there are no water leaks in concealed plumbing chases. Return air paths and plenums shall be kept dry.  All existing supply air paths and all existing ductwork to be re-used shall be cleaned and treated as required to remove the potential for mold and mildew.   All damp areas shall be dried thoroughly prior to enclosure.

Back to Top