Most research efforts that test the effects of moisture exposure on wood building products evaluate the effects of water vapor — in other words, the relative humidity (RH) — rather than exposure to free water. In the insurance industry, investigating and defending the duration of loss are fundamental tasks in every water-related property claim. Interviews with the insured and third parties, examination of the source and extent of damage, documentation of the condition and degree of deterioration, and the presence and extent of microbial growth all contribute essential elements to make this determination.

The interpretation of a water loss is often based on the investigator's experience and comparisons to similar losses. Quantitative research comparisons are not generally conducted. This study reports that the behavior of water by capillary attraction is both predictable and useful in refining estimates about the duration of a water loss. Capillary attraction is the movement of a liquid along the surface or a solid caused by the attraction of molecules of the liquid to the molecules of the solid.

This study examined water absorption via capillary attraction on common building materials by measuring changes in moisture content and dimension over a month (34 days) period. One month was chosen because it represented twice the typical covered loss period in most policy limit provisions that state, “Loss of damage caused by or resulting from continuous or repeated seepage or leakage of water, or the presence of condensation of humidity, moisture or vapor, that occurs over a period of 14 days or more.”