Wood Is Rotting
Problem: Excessive moisture is
causing wood in home to deteriorate.
Background: Decaying wood is more permeable to
moisture, and therefore, is more subject to further damage
and decay. Discoloration on wood may be mold (see
and Mildew Inside Home); however, symptoms of wood
decay are also often recognized by color. Both white and
brown rot are serious and deserve treatment or war rant
replacement of the wood.
White rot, the most difficult damage
to recognize, is probably the worst form of wood decay.
Wood with white rot appears somewhat whiter than normal,
and sometimes has dark lines bordering the light
discoloration. Though affected wood doesn’t always shrink
or collapse, in advanced stages, some cracking occurs
across the grain.
Brown rot appears as a brown color or
brown streaks on the face of the wood or end grains. In
advanced stages, the wood looks very damaged, with the
surface shrinking and collapsing and with cracks across
Soft rot and blue stain are less
damaging, slower-acting forms of wood decay that tend to
be more active on the surface. With soft rot, the wood
surface appears soft and profusely cracked, resembling
driftwood in color. A blue stain indicates somewhat
weakened wood, with blue, brownish black, or steel gray
staining. The discoloration is not a surface stain; it
penetrates the wood cells.
What to do: The most common
method of detecting external decay is the pick test, using
a sharp, pointed metal tool. An icepick, small chisel, or
small screwdriver can be jabbed into wood and used to pry
or lift wood slivers. A splintering break of wetted wood
indicates sound ness, while a sharp break across the wood
grain suggests decay. Decayed wood breaks out with less
resistance, is easily penetrated by a pick, and may have a
rough or fibrous surface. When cut with a saw, wood
affected with even early stages of decay produces a
rougher finish cut than wood that is not infected. When
jabbing wood with a pick, start at ground level or below
and work up. Check whether areas that look soft have other
symptoms of decay, such as color and texture changes.
Special advice: Another test is to tap the wood’s
surface; good, dry wood produces a sharp, clear, almost
ringing sound and wet or decaying wood produces a dull,
dead, soft sound.
Helpful hint: If you
detect wood rot caused by excess moisture, try to correct
the source of the problem, whether it is moisture from
inside the house or moisture leakage into the house. You
also may need to take steps to reduce humidity movement by
stopping air leakage into wall, ceiling, and window
cavities and by reducing high humidity with ventilation
and membrane vapor retarders installed in crawl spaces,
below ground walls, and basement areas.