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Moisture Testing

Today's Media has been very good at informing the public of potential moisture problems in homes. The media is also very good at presenting only the worst or most extreme cases. While some cases can be very severe, we have also found many cases where moisture damage is easily repaired.

Homes built after 1988 seem to have an increased risk of containing abnormal moisture. Some studies suggest this risk may be as high as 90%. Certain types of siding material, especially stucco and EIFS (Exterior Insulated Finish System) together with methods of installation appear to be a major contributing factor. Poor assembly of wall and roof systems may be another cause.
Moisture testing will confirm the presence of or lack of abnormal moisture. This information can be extremely valuable to potential homebuyers and sellers. For others, the information may be used to direct the type of repairs needed, or it may simply provide peace of mind that no abnormal moisture was found.

If your siding appears to have stains, streaks, or discoloration, especially near windows, doors or roof edges, this may be a sign of potential moisture problems. If these signs are present, we strongly recommend that you investigate for moisture in walls. Seasonal changes can effect the amount of moisture in walls.

Moisture testing and evaluation requires the use of special equipment and is not part of a standard home inspection. There are many forms of moisture testing but only intrusive testing will confirm moisture level within a wall cavity. You should be wary of anyone who recommends ultrasonic or infrared testing to confirm the presence or absence of abnormal moisture in walls.

Intrusive testing involves drilling two small holes into the wall from the outside. Test probes are inserted into the wall to measure the moisture level. A moisture analysis report will describe the areas that are tested and digital photos will document the test locations. Moisture levels in walls will be measured at multiple depths and recorded in the analysis report. Typically, areas chosen for testing are based on visual evaluation of design features where elevated moisture levels may be expected. If we discover abnormal moisture in prime locations, we can expand testing to include other areas. If abnormal moisture is not discovered in prime locations a decision can be made to discontinue testing.

Moisture levels under 10 percent WME is considered to be normal although many homes may have readings between 10 and 15 percent WME.

Moisture levels between 16 and 19 percent indicate moisture intrusion and modification may be necessary to reduce moisture levels. This may include caulking or installing flashing. We recommend that you retest these areas six months after repairs have been made to confirm lower moisture levels. The retest can be performed using existing holes.

Moisture levels over 19 percent are considered to be excessive and may indicate structural damage. If moisture levels exceed 19 percent and/or wood sheathing is found to be soft or undetectable at test holes, the wall may need to opened and examined for structural damage. If a decision is made to open the wall, contractors will need to be involved to repair any damage.

Special permission must be obtained from the building owner prior to any intrusive moisture testing.

Since every home is different, we suggest that you give us a call to discuss your specific needs. We also suggest that you visit "A Brief Guide to Mold, Moisture, and your Home"
  Fred Comb
Home Inspections of Minnesota
190 Wildwood Bay Drive
Mahtomedi, MN 55115

Office: (651) 653-7111
Cell: (612) 840-0709

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