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Chapter 2 - Why and Where Mold Grows

Lesson 6 - Crawl Spaces

Chapter 2 - Why and Where Mold Grows

Lesson 1
Introduction to Mold Growth

Lesson 2
Moisture Problems

Lesson 3
Humidity

Lesson 4
Ventilation Humidity Problems

Lesson 5
Structural Integrity and Mold Growth

Lesson 6
Crawl Spaces

Lesson 7
Floods

BEGIN KNOWLEDGE TEST

Pooled water under plastic sheeting used in crawlspace.
Click image for larger version

Crawl spaces where relative humidity (RH) is high are common sites of hidden mold growth, particularly if the crawl space has a bare earth floor. The soil will wick moisture, through capillary action, from moist to dry areas. The relative warmth of the crawl space will dry the soil by evaporation, adding this moisture to the air in the crawl space where it can cause mold to grow. Also, in areas where the water table is high and weather conditions are suitable, ground water may enter a crawl space.

The moisture that accumulates in a crawl space may also enter another part of the building and contribute to mold growth there. Moisture can pass from a crawl space into a building through cracks in walls, floors, and ceilings.

Crawl spaces should be designed specifically to avoid moisture problems. For information on constructing crawl spaces and other building features, see the Resource List.

Drying Buildings, Building Materials, and Furnishings

Drying a carpet with a commercial specialty blower with built-in heater.
Click image for larger version

Buildings and building furnishings will often get wet. They must be dried or "allowed to dry" quickly (within 24-48 hours) in order to avoid mold growth. In general, increasing air circulation and temperature will increase the speed of drying.

Commercial firms that do mold remediation work or work on water- and fire-damaged buildings often use large fans, dehumidifiers, and other equipment to dry wet buildings and items quickly before mold has a chance to grow. This action can save money in the long run, because if the building or furnishings are dried completely and quickly, mold will not grow, and a mold remediation will not be needed.

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