Delmhorst Instrument Moisture Check - Manual (Page 22)

Copyright  2005, Delmhorst Instrument Co.
Page 22 of 29
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To take a reading, align the contact pins parallel to the grain and push them to their full
penetration into the wood, if possible. Insulated pins read only at the tip and can be driven to
the desired depth.
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Press the SELECT button and read the moisture content on the meter scale. The meter
displays the %MC for two seconds.
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To add a reading to the previously stored readings, release the SELECT button if you are in
triggered mode. If you are in continuous mode, the meter will not store a new reading until
the SELECT button is pressed and released again during the reading cycle.
NOTE: MC RANGE AND VALID READINGS
Readings below 5% or above 60% are displayed as LOW or HIGH, respectively. However,
since the resistance of the wood also depends on the species and temperature of the wood, the
meter may not always be able to read down to 5%. For different species and different wood
temperatures, there is a minimum %MC limit below that the meter can not read. All readings
below this “lowest limit” are displayed as LOW, and are not stored. These readings are not
considered valid readings and are not used by the meter in any statistical calculations.
PAINT FAILURE AND MOISTURE
Moisture is by far the most frequent cause of paint failure. The key to preventing paint failure is to
insure that moisture is not absorbed through the wood to the back of the paint film. So, in order to
insure quality paint jobs, wood must remain dry after the application of paint.
Outdoor wood can be safely painted without danger of peeling if the %MC is 15% or less. In drier
climates, the maximum reading should be 10% to 11%. Indoor wood should be between 7% and
8% prior to painting.
The following conditions may cause high moisture content in wood:
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Leaky gutters and down spouts
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Leaky pipes or condensation on cold water lines in attic or hollow walls
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Faulty flashing around windows, doors and where porch and dormer roofs meet sidings
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End-grain wood that is not sealed with paint at all joints around windows, corners, and butt
joints
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Porch columns that do not have good drainage and ventilation where they rest on porch
floors
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Siding or any other wood that is in contact with the ground may absorb moisture
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Siding and shingles without sufficient lap so that water is forced up through cracks by wind
pressure
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Ice dams
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Condensation of vapor within hollow walls
EIFS (Exterior Insulation & Finish Systems) *
Moisture intrusion problems in EIFS (also known as synthetic stucco) stem from leaking window
frames, improper use of or lack of sealant, and faulty installation of flashing.