Delmhorst Instrument BD-10 - Manual (Page 7)

6
USING THE 0-100 REFERENCE SCALE
Testing Concrete Slabs for Flooring
Applications
Moisture meters are an effective tool to check moisture in
concrete. They can tell you where there may be excess moisture
and help determine if you need to conduct further testing.
It is important to test both the surface and mid-section of the
slab, especially if the slab is on or below grade. This will help
determine if there is continuous moisture migration toward the
surface. If this condition exists, the moisture movement may
be so slow that once it reaches the surface, moisture evaporates
and causes a “dry” reading when a surface test is made.
However, if a sub-surface test is made, the meter may read
“wet” indicating the presence of moisture. When the slab is
covered and the upward movement of moisture continues, moisture
will move into a hygroscopic (wood) floor, or build-up pressure
under a non-breathing synthetic floor, causing delamination.
Taking a Surface Reading:
hDrive two hardened-steel masonry nails about 3/4”
apart into the finish coat of concrete floor. Drive them
about 1/8” deep so they make firm contact with the
concrete and do not move when touched.
hTouch the nails with the contact pins
%
.
hPress read button
!
and read the reference scale
$
.
If the meter reads in the red or “wet” area, it shows the
floor is not satisfactory for covering. If meter reads in
the green or “dry” area, the surface is dry. However,
subsurface tests should be made to verify if the slab is
dry throughout.
Subsurface Test:
hDrill two 1/4” holes, 3/4” apart and 1/2” to 2” deep.
hDrive the masonry nails into the bottom of the holes and
make the tests as described above. Nails must not touch
sides of drilled holes.
➝
➝
➝
➝
➝
6” nails 1/8” into
concrete
Drilled holes 1/4” diameter.
Nails 1/8” into concrete at
bottom of holes.
2-3” approx.
slab
electrode
subsurface