Dry Rot and Structural Repairs
DRY ROT - WHAT IS IT ?
The term "dry rot" is actually inaccurate. Generally, it is used to describe wood decay. More accurately,
it is the decay of wood, caused by fungi capable of carrying water into the wood it infests. In late stages, the wood becomes
crumbly and powdery, losing all of its structural integrity. Unless the avenue of moisture infiltration is sealed off and
the infected wood and water concentration removed, the deterioration continues. California has enough moisture throughout
the year for this fungus to grow and continue its attack. Areas of dry rot often begin at end cuts of wood and spread outward
from the point of origin. Roof eaves, trim boards and siding are common areas of exterior infiltration.
DRY
ROT - WHY IS IT A PROBLEM ?
First, dry rot is almost invisible to the untrained eye until it’s
late stages. Second, most owners have no way of determining if poor construction techniques were utilized during construction.
Third, seismic movement, settling of the structure and even the wind can make a building susceptible to water infiltration.
Finally, simple old aging should not be ignored. If left untreated, rot will continue to spread to the adjacent wood members
and can cause complete areas of a structure to be removed and replaced.
DRY ROT – HOW TO IDENTIFY
THE SOURCE
The most important thing to do once dry rot is discovered is to determine where the water is coming
from. The following is just a sample of the areas to inspect. Check the attic for roof or plumbing leaks. Inspect for damaged,
punctured or missing flashings. Are the rain gutters damaged, full of debris or even missing? Peeling and blistering
of interior or exterior paint can be a sign of inadequate interior ventilation. Water staining on the framing members and/or
sheathing at inside walls can suggest condensation problems. Once the water source has been identified and corrected, the
removal of damaged wood must be performed.
DRY ROT - STRUCTURAL REPAIRS
The correct replacement
of damaged / dry rotted building components is especially important when dealing with load bearing members such as ceiling
and floor joists, rafters, girders, columns, interior and exterior bearing walls and other critical components whose ability
to bear a significant load may have been compromised. There is no known way to determine accurately the remaining strength
of damaged wood left in place. If, in rare cases a partially damaged structural component can't be replaced, it may be
possible to augment or reinforce it utilizing a repair technique called a "Sister".
“Sistering” is a repair which first cuts back the rotted member to sound wood. Next,
a component of equal or greater load bearing capacity is anchored to the remaining sound wood. Always keep in mind that the
full extent of dry rot can be difficult to determine until the demolition phase is complete and may extend well beyond the
visibly rotted areas.
