Cupping and Crowning Continued
In basement
construction, the soil drainage solution applies, but it may be necessary to dig
out and waterproof the exterior of basement walls, and install drainage near the
bottom of footings as well as intermittently up the side of the basement walls.
Because of the expense involved this should be considered only as a last resort.
Mechanical dehumidifiers in the basement plus summertime ventilation may ease
the problem enough to allow the subfloor and surface hardwood to dry.
The next step is to allow the floor and all underfloor construction to dry
thoroughly. The process by which hardwood floors take on moisture and expand
takes many weeks, unless water in liquid form has been in the picture. By the
same token, its removal may also take several weeks, or even months. Once a
program of drying has been set up, evidence that it is working can be seen
within a short time. Its progress should be monitored by taking moisture
readings on a bi-weekly or monthly basis, and no repairs should be attempted
until the readings have remained balanced between face and back for 30 days to
be sure that cupped floors have flattened as far as they are going to. (Floors
with a surface finish react much more slowly to moisture changes.)
WHEN THE FLOOR RE-FLATTENS:
If cupped floors flatten when
they have dried, new considerations of a complete repair may arise:
Fastenings
-- nail installation: The cupping action may have
loosened nails to some extent. If so, this will express itself by squeaks or
looseness when the floor is walked on. Face nailing or fastening from underneath
with wood screws will correct the problem.
Adhesion
-- mastic installation: Some types of wood floor mastic
have re-tack properties which will allow the mastic to re-adhere even after the
floor has been pulled loose and reset. If walking on the floor produces popping
sounds, or the floor sounds "hollow" when tapped, adhesion has probably been
lost. In this event the affected parts of the floor must be removed and replaced
to accomplish an effective repair.
If an asphalt cut-back mastic was used originally, the dried-out floor can be
removed and replaced (a few pieces at a time), as the mastic can be reactivated
with a light spray of kerosene. Headless pins of hardened steel can be used also
where mastic adhesion has been lost. These pins can be driven into either wood
or concrete subfloors.
Once fastenings are secure, the floor can be filled where cracks exist, and
either given a new coat of finish, after screening, or buffed with No. 00 steel
wool, cleaned, and re-waxed. If the original finish was a surface type (i.e.,
Polyurethane), it can be re-coated only if it has not been waxed.
WHEN THE FLOOR REMAINS CUPPED
after thoroughly drying it has
most likely set new stresses and most boards will remain cupped indefinitely. In
this case the only practical repair is a complete resanding and finishing job.
Cracks should be filled as a normal part of the finishing process and fastenings
checked and repaired before sanding.
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