NEW BUILDINGS AND MOLD
Since the energy crisis of the 1970”s, “energy efficient” construction techniques have contributed greatly to mold problems by reducing fresh air exchange and diminishing a building”s ability to shed excess moisture.
The problems are caused by:
- Thermal insulation
- Tight building enclosures
- Recirculated forced air heating and cooling
- the elimination of chimneys
Thermal insulation reduces the drying potential of a building enclosure. It limits the flow of heat and air through building assemblies, diminishing their ability to dry if/when they get wet from interior or exterior sources. This problem has nothing to do with climate.
“Tight” buildings have led to increased moisture that can result in mold and mildew. Some suggest that buildings build in the 1990”s were nearly twice as tight as those constructed in the 1950”s. While buildings were getting less airflow efficient, new chemical compounds were being introduced to interior air. Low air change rates began increasing hte potential for mold, mildew and indoor pollution from the new chemical compunds, materials and products.
Recirculated foced air heating and cooling within a tight building have let to health, safety, durability and operating cost issues.
Chimneys acted like exhaust fans that extracted large quantities of air from the conditioned space, resulting in frequent air changes and dilution of interior pollutants. Their elimination has added to air quality problems.
These “improvements” were meant to conserve energy while making homes more comfortable. Instead, they”ve contributed to structural deterioration, insurance problems and comfort, health and safety concerns.
Construction materials have also changed in recent years. They have shifted from substances that discourage mold or bacteria to materials that invite problems.
Builders have gone from plaster on cedar lath (with a lime coat that was to oalkaline for mold and bacteria) to drywall, which holds moisture. Pipes have gove from iron to copper to plastic – which is more likely to leak. Outer walls and shower stalls may leak into unventilated cul-de-sac wall spaces.
Adding to the problem – today”s air conditioning ducts are poorly insulated and depend nearly exclusively on ducted air.
As mold develops on a surface, it produces enzymes to digest orgainc materials, such as wallboard, wood, carpet backing, paper and personal items, etc. Some are especially fond of cellulose materials like wood, wallboard and ceiling tiles; these molds can cause health and structural problems.
These properties require professional mold remediation in order to be brought back to normal fungal ecology.
Remediation involves:
- Reversing conditions that favor fungai growth
- Correcting defects in construction and services
- Reducing or isolating available nutrients
- Monitoring the building to prevent conditions that favor fungal growth
