Most people are unaware of certain environmental conditions that can actually lay the foundation for the growth of mold in a home or building. These existing conditions often are seen in areas near large bodies of water, as is the case with the City of Oakland in California.

The specific conditions necessary for mold growth to occur are as follows: Temperature range above 40°F and below 100°F, existing mold spores, a nutrient base, and moisture. In an area with a moderate climate like Oakland and much of the San Francisco Bay Area, all these conditions are met and it is very important to know if mold is present and how it can be prevented.

For mold growth to occur moisture is necessary and this can result from stagnant water, as well as areas of high relative humidity. High relative humidity of a given material demonstrates how much water it can actually absorb or hold. If a room has a temperature of about 70°F and there is a part of the room that has a lowered temperature (at or below the dew point) this can mean several different things: there could be a gap in the insulation, unsealed windows located at a wall joint, etc. It is at these cold spots that condensation can occur and mold can begin to spread. This spot is referred to as the “first condensing surface.”

Since moisture is necessary for mold to be present, it should be known that water can enter a building as a liquid and as water vapor. Generally speaking, water can be found in places that have a running water source, such as a bathroom, laundry room, or kitchen, but can also be the result of a leak.


Water vapor can make its way into a building through the HVAC system, via openings in windows, doors, and wall insulation. It should be noted that even though moisture content is lowered in a home or building, inactive mold spores are still present, and when water is reintroduced, they will begin to cultivate again.

Some of the ways to eliminate the possibility of moisture intrusion, either as liquid or water vapor, is as follows: maintaining a Relative Humidity (RH) that is below the dew point, proper ventilation, or increasing the temperature of a room or entire building. Some tips to minimize the factors involved in mold growth in areas near the coast are:

Maintain humidity levels below 60-70% depending on location, as living near the coast may result in re-occurring problems.

Allow outside air into the home.

Make sure there are no gaps in the insulation, as this can lower surface temperature.

Install vents in closets or confined spaces in a home to help circulate air.

Use dehumidifiers if high humidity is present.

Make sure that caulking in rooms with a running water source is in good shape.

Clean bathrooms regularly and ventilate during and after showers.

Reduce clutter in closets and rooms.

Coastal regions, as stated above, can be a prime environment for mold to grow and rein havoc. For example, Oakland’s historic town hall has had known mold issues since 2009 and Lisa Waldron, the administrative services director of the building has been attempting to quash the growing problem ever since. “Moisture has permeated the north side wall and the space between the historic vault and the outer wall,” Waldron said. The mold had begun to grow in this historic building due to leaks in the air-conditioning unit and also the roof. The continued intrusion of water into the structure due to cracks in the exterior, have allowed for mold to continue growing there, and the costs to repair the issue have continued to rise.

It is very important to identify the issues in a structure that may allow for moisture intrusion, especially in a coastal climate, or problems concerning mold growth will continue. It is also important to note that if such issues are not resolved, the structural integrity of a building can be damaged, as well as the health of the inhabitants within the dwelling. If mold growth is present it is necessary to have a certified inspector test any areas of concern. If problems are found, professional remediation of those areas affected should be conducted.