12
Testing Brick or Concrete for Paint Application
Brick, stucco, or concrete surfaces must be dry at the time of
application and must remain dry after paint is applied or failure
of the paint film may occur. These materials are frequently
exposed to unusual moisture conditions that allow them to absorb
moisture through some exposed surface or some structural defect.
This is why it is important to check the moisture levels of the
brick or concrete when it has been exposed to conditions that
permit it to absorb moisture.
Procedure:
h
Drive two hardened steel masonry nails
about 3/4” apart into
the brick or concrete. Drive them about 1/4” deep so they
make firm contact and do not move when touched.
h
Touch the nails
with the contact pins
^
.
h
Press read key
!
and read the meter.
Normally, dry concrete or brick will read in the green or “dry”
portion of scale, indicating a safe condition to apply paint.
Meter readings should be evaluated in relation to other factors —
knowledge of the structure, type of paint used, expected weather
conditions in the near future, etc. Paint should not be applied if
readings are in the red or “wet” portion of the scale.
Do not be misled by surface appearance of masonry materials.
Short exposure to rain may thoroughly wet the surface while
the interior is still dry. In this instance, we recommend repeating
the test on the masonry
below the surface
as mentioned above.
Key Areas to Check:
h
The rear side of brick parapet walls —
generally are not
waterproof above the flashing line and frequently absorb
moisture during rains.
h
Painted concrete floors on grade —
subject to peeling as
they absorb moisture from the earth, unless an effective
vapor barrier has been installed.
Tests on these materials should be made a day or so after they
have been exposed to rain or other high moisture conditions to
verify to what extent they absorb moisture.
Tracing Leaks
The BD-2100 can help trace leaks in masonry material.
Normally, dry plaster, brick, or concrete will contain so little
moisture it cannot be detected by the meter. If the meter
indicates the presence of moisture you can trace the moisture
to its origin.
To trace the origin of a leak:
h
Drive a nail into an area that is known to be wet
and attach an
insulated wire between the nail and one of the contact pins
^
.
h
Apply the other pin to various parts of the wall
where you suspect
the leak originates. If the meter indicates red or “wet”, the material
is wet between the points of contact. If the meter reads green or
“dry”, the material along this line is not in the path of a leak.
To confirm if a brick wall is waterproof:
Perform the following procedure after storms to verify if a brick wall
is waterproof, or if waterproofing repairs have been properly performed:
h
Drive pairs of nails into the brick
wherever it is necessary to
make the tests and leave them in place until after all the tests are
completed.
h
Take readings after each storm,
and record the readings. The
pattern of these readings will indicate if the brick is gradually
drying out or is moistened again by each storm.
Detecting Moisture in Insulation
Use the
BD-2100
with the
#21-E Electrode
and
#608
insulated pins
to detect moisture in insulation. These pins
penetrate 3 1/4" and are insulated, except at the tips. Only
the uninsulated tips make contact with the material,
providing information as to the depth at which moisture is
present. Also available - #608/001 insulated pins with 6"
penetration.
Procedure:
h
Drill two 3/16" diameter holes,
one inch apart through
the siding or drywall.
h
Using the #21-E,
insert the #608 contact pins into the
holes so that you make contact with the insulation.
h
Press the read key
!
and take a reading. Take readings at
various depths of penetration to determine the location of
moisture.
h
Seal holes with an appropriate filler
at the conclusion
of the test.
Meter readings provide a qualitative indication of the
presence of moisture. Meters are not calibrated to read the
percentage of moisture content in the insulation. The meter
may also help identify the pattern of distribution to help
you determine if moisture is due to condensation or
leakage.
13
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