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Making
Waves
by
David Barkstedt
Elite
Consultants Inc.
I received a phone call from a
consumer who commissioned me to
inspect her prefinished solid wood
floor. The floor had been installed
last winter and since then had
become “wavy” across the width of
the boards. The consumer first
noticed this condition during the
summer. The wavy appearance she was
describing was actually cupping.
The
Procedure
The
floor was installed over a wood
subfloor in the living room and
hallway during the previous winter.
The subfloor in the living room and
foyer were installed over a
crawlspace with no vapor barrier and
no ventilation. The subfloor in the
hallway was installed over an
existing basement with a concrete
floor. From a conversation with the
installer, I discovered that he had
not performed any pre-installation
moisture testing and had not
examined the conditions over which
the subfloor was installed. The
installer also had not acclimated
the flooring prior to installation
(as required by the flooring
manufacturer). I carefully examined
the floor and tested for moisture
using a non-invasive moisture meter
and a pin-type moisture meter. I
used a probe-type moisture meter
that measures electrical resistance
across the opposed sets of pins that
are pushed into the wood parallel
with the grain. I then used a
pin-less dielectric moisture meter
with a signal penetration up to
1inch that can give a moisture
reading indication of the subfloor.
These two tests revealed moisture
imbalances between the wood floor
and the subfloor. There was a
moisture imbalance of greater than 4
percent, giving cause for concern.
The
Cause
The
moisture imbalance allowed the
boards to cup or, as the consumer
stated, become wavy. As humidity
levels increased during the summer
months, moisture from the crawlspace
migrated up through the subfloor
into the wood floor.
How to
Fix the Floor
The
first item to address was the origin
of the significant moisture. A vapor
barrier was installed in the
crawlspace, as well as adequate
venting to allow for cross
ventilation. Once that had been
done, the moisture levels between
the subfloor and wood floor had to
equalize. In situations such as
this, the time needed to allow the
moisture to become balanced through
the wood floor and subfloor could be
up to a year or through a complete
heating and cooling cycle. After the
moisture imbalance is stabilized, it
may be necessary to sand the floor
flat and refinish. Sometimes after
stabilization has occurred, the wood
floor returns to an acceptable
appearance and/or condition.
Unfortunately, in this particular
floor, the boards did not flatten to
an acceptable appearance through
stabilization of the moisture
conditions. There were additional
installation concerns, and the
consumer currently is proceeding
with legal measures against both the
installer and the retailer..
In the
Future
The
installer/retailer is responsible
for checking to see if the job-site
conditions are acceptable for a
solid wood floor installation. These
checks should be done long before
the installer arrives on the job
site to start the installation. In
this case, a quick inspection when
the job was estimated would have
revealed that the crawlspace was
unacceptable, and therefore the job
site was not ready for a wood
flooring installation. Current
guidelines for crawlspaces are that
they must be dry (no apparent
moisture or standing water) and must
be covered 100 percent by a vapor
retarder of 6-mil black
polyethylene. Crawlspaces also
should have 1.5 percent of open
venting per 1,000 square feet (92.90
square meters) of floor area, and
the venting should be properly
located to foster cross ventilation.
In addition to these guidelines,
installers must check and follow
local building codes.
In this
case, not checking the crawlspace
was the worst problem, but it was
far from the only problem. Moisture
meters can be an installer’s best
friend. Moisture content readings
should be done on different areas
throughout the subfloor. Adequate
acclimation of solid wood flooring
prior to installation is a must, and
moisture content readings of the
flooring must be within 4 percentage
points of the subfloor moisture
content before installation can
begin. Hygrometer and thermometer
readings must show that the job site
is at acceptable temperature and
relative humidity levels. In this
case, none of these readings were
taken. This also means that the
manufacturer’s directions were not
followed. Installers may get away
with ignoring these requirements on
some jobs, but eventually a job like
this one will cost them, just as
it’s about to for the installer on
this job.
Dave
Barkstedt is senior
consultant/inspector at
Saugerties, N.Y.-based Elite
Consultants 845 246-4414
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