4.505.3 Moisture content of building materials. Building materials with visible signs of water damage shall not be installed. Wall and floor framing shall not be enclosed when the framing members exceed 19 percent moisture content. Moisture content shall be verified in compliance with the following:
1. Moisture content shall be determined with either a probe-type or a contact-type moisture meter.
Equivalent moisture verification methods may be approved by the enforcing agency and shall satisfy requirements found in Section 101.8 of this code.
2. Moisture readings shall be taken at a point 2 feet (610 mm) to 4 feet (1219 mm) from the grade stamped end of each piece to be verified.
3. At least three random moisture readings shall be performed on wall and floor framing with documentation acceptable to the enforcing agency provided at the time of approval to enclose the wall and floor framing.
Insulation products which are visibly wet or have a high moisture content shall be replaced or allowed to dry prior to enclosure in wall or floor cavities. Wet-applied insulation products shall follow the manufacturers’ drying recommendations prior to enclosure.
COMMENTARY
Purpose:
The purpose of this section is to provide additional protection against growth of mold or other biological growth in moist enclosed areas. This section requires field verification of moisture content and prevents enclosure of wood framing members exceeding 19 percent moisture content. This section also prevents the enclosure and use of wet or moist insulation products.
Examples of Acceptable Methods of Implementation and/or Compliance:
Cover building materials to protect from rain and moisture.
Ensure building is weather-tight before insulating.
Use other precautions necessary to ensure building materials are kept dry.
Test for moisture levels of building materials.
Moisture sensors are available for purchase and range from $80 to $200.
To comply with the requirements of this section, moisture readings must be properly taken and recorded and made available for review by the enforcing agency. The code also allows equivalent methods of moisture verification as allowed by the local enforcing agency.
Background:
Wood construction is the most commonly used form of building construction in single-family and multi-family homes today. Freshly cut wood often displays moisture content levels of 30 percent and higher. Levels of this magnitude, especially when enclosed and prevented from drying, could cause serious problems with constructability as well as long-term building and occupant health.
Commonly used by building inspectors as a criteria for serviceability and performance of wood products; the maximum allowable 19 percent moisture level is the performance threshold for kiln- drying for many building codes. Section 4.505.3 details the requirements and methods to insure that the supplied building materials are safe for installation
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