Attic Wetness – Pattern of Condensation vs Pattern of Leakage

Posted by in Attic Ventilation, Roof, Simple Forensic Methods, Water Sources, Winter Concerns | April 21, 2014

We are often called to evaluate the source of moisture causing mold growth, water damage or wetting of building components.  These conditions may be in an attic, a living area, a crawlspace, a basement, a garage, etc.  The source of the moisture may be water supply line leakage, sanitary line leakage, plumbing fixture leakage, condensation of excessive airborne moisture, roof leakage, siding leakage, window leakage, etc.  One of the physical evidences that are helpful in evaluating these is the pattern of damage.

Leakage is generally evidenced by an isolated area of wetting, moisture/water staining, water damage, mold growth, etc.  (See Figure PCPL-1).  These limited areas of damage can usually be traced or reckoned back to a source, such as, breach in a water supply line, a sanitary line, a plumbing fixture leakage, roofing system, siding, window flashing, etc.  If the source of the moisture or water is allowed to continue for an extended period of time, the limited area may be large, but again it will trace or reckon back to the source.

PCPL-1 Isolated moisture staining on attic framing.

Condensation is generally evidenced by a widespread pattern of wetting, moisture/water staining, water damage, mold growth, etc.  (See Figure PCPL-2).  There may be limited areas of more severe damage due to areas of more concentrated, prolonged, or more repeated wetting from condensation.  These are generally in areas where air flow is more restricted.  In contrast, areas lacking wetting, moisture/water staining, water damage, mold growth, etc. from condensation are generally in areas where there is more air flow present, such as, near ridge vents, roof vents, fans, HVAC vents, etc.

PCPL-2 Widespread pattern of moisture staining in attic.