Mold in the Attic, Bats in the Belfry

Why be Concerned about Mold in the Attic?

We frequently are asked to remove mold from a residential attic.  There is little doubt that it occurs under certain conditions.  Is it, however, a health hazard?

It is useful to remember the air dynamics of any building, including your home.  Warm air rises and you can try to stop it but you won’t.  Starting from the basement, air is heated, either by winter time heating or just plain hot weather, and moves upward.  This convection forces air out of the basement and eventually the air arrives in the attic.

The reason that we ventilate an attic is to release the air, and attendant moisture t
hat it has absorbed, so that it does not accumulate in the space.  Back in the day, this was pretty straight forward, since there were not many moisture sources in the home that added to the moisture load.  A couple of gable vents were usually sufficient to vent the air (and moisture).

Fast forward to the present and there are many more moisture sources to manage. Just a simple thing as replacing clapboard or asbestos siding with vinyl changes the whole ventilation dynamic of the home.  Vinyl is impermeable and the air that used to get to the home and attic does not.  The home no longer breathes the way it used to. [Read more…]

What I Consider a Mold Activity: The Primer

Clients frequently ask us, “How are you able to find mold problems when I don’t see anything and neither does anybody else.” Or a common variation on this theme, “I have a mold test but I don’t know what it means.” Our answer is, we follow the Sherlock Holmes investigative approach that has been described in virtually all of the published standards.

What does this mean? It means that you look for clues, which means you are looking for data. And you can’t really evaluate data unless you understand what it signifies. You need some basic understanding of the critter you are pursuing. Let us start at the beginning. [Read more…]

Mold Standards: Do They Exist?

We have stated that there are no accepted numerical standards for mold concentrations. Several previous attempts at suggesting numerical concentrations have failed due to the enormous diversity of the thousands of mold species that naturally occur, and to the wide variability in human responses to these species. Most professional doubt that we will ever have a set of exposure limits like we have for other indoor contaminants such as radon, asbestos and lead.

This does not mean, however, that there are no standards with which to conduct a competent assessment or remediation project. Numerous public and private agencies in the US have written standards for biological contaminants, starting with the Environmental Protection Agency (EPA) and the American Conference of Governmental Industrial Hygienists (ACGIH) in the late 1980’s. The body of professional standards has grown steadily since. A sampling of the evolution of professional industry standards is shown below. [Read more…]

Mold Remediation Procedures

We reference the industry standard Bioaerosols: Assessment and Control (1999), published by the American Conference of Governmental Industrial Hygienists (ACGIH). The ACGIH standard is the current authority on biological contamination, and is a practical guide for identifying and correcting suspected sources of microbiological amplification. Several other industry guides have been published in recent years, including:

  1. Environmental Protection Agency (EPA) Mold Remediation in Schools and Commercial Buildings, EPA 402-K-01-001, March 2001.
  2. Environmental Protection Agency (EPA) Guide for Building Owners and Facility Managers, ISBN-0-16-035919-8, published in December, 1999.
  3. Institute of Inspection, Cleaning and Restoration (IICRC), Standard and Reference Guide for Professional Water Damage Restoration, IICRC S500, 1999.
  4. New York City Department of Health (NYCDOH), Guidelines on Assessment and Remediation of Fungi in Indoor Environments, May 1993, Revised March 2004.
  5. American Industrial Hygiene Association (AIHA,) Field Guide for the Determination of Biological Contaminants in Environmental Samples 1996.
  6. American Industrial Hygiene Association (AIHA), Assessment, Remediation and Post Remediation Verification of Mold in Buildings, AIHA Guideline 3, 2004.

As described by EPA and ACGIH, and supported by publications by the American Industrial Hygiene Association and the National Institute of Occupational Safety and Health, the amplification of biological populations should not be tolerated in occupied buildings. The presence of amplification requires mitigation measures to remove the biological growth. Existing industry standards indicate the need to remove affected porous materials, clean affected non-porous materials, and thoroughly clean all surfaces in the area of the contamination. Caution is advised in the use of disinfectants, to ensure that building occupants are not exposed to chemical biocides that can be hazardous with uncontrolled use.

[Read more…]

Mold Inspection: How is it Done?

The inspection process includes a general understanding of the building, including age, number of stories, roofing and siding type, and presence of basements or crawlspaces.

The behavior of moisture in the structure is the critical component of the assessment. The grading around the building should be reviewed to ensure the water flows away from the foundation. This is especially important in the area of roof leaders and drains. Some grading issues are a challenge by definition. For instance, if a home has a walk-out patio door on one side of the basement and the rest of the basement is below grade, this implies that the grade slopes toward the house on the other side. [Read more…]