Moravian Preservation Master Plan.indb - Society for College and ...

Moravian College • Preservation Master Plan
Termites typically are found in basements and crawl
spaces and in situations where wood is in direct
contact with soil or mulch. They have been known
to enter slab-on-grade buildings through tiny
cracks in the slab. Their constant traffic results in
mud tunnels and passageways on vertical building
surfaces, usually at-grade or slightly below grade.
Tiny specks or piles of sawdust are also telltale
signs of termite activity.
Carpenter Ants
Like termites, carpenter ants usually attack a
building from a crawl space or basement and are
they are attracted to moist wood. Carpenter ants are
a natural resident of our surrounding woodlands
and so are frequently present around historic
buildings. Their nests can be extensive and cause
serious damage to a structure.
Carpenter Bees
Carpenter bees swarm in the spring and bore
holes into vertical wooden elements. These bees
are substantially larger than the honey bee and
produce sizeable holes up to ½ inch in diameter
in which to lay their eggs. Breaking the cycle is
therefore important and professional treatment
is recommended. They can be very destructive
and are attracted to the type of thick framing
members typically found on log structures. Other
buildings are not immune however: large wooden
architectural features, such as exposed rafter ends,
solid wood columns, and half-timbering, can host
carpenter bees.
Beetles
Powder post beetles are attracted to wood that
has already been softened by rot or fungal attack.
Preventing moisture penetration, repairing
deteriorated wood features, and fungal removal
are effective preventive maintenance techniques
for beetles.
Old house borer beetles in their larvae stage cause
damage to wood, especially in moist wood found in
unventilated attics or in areas of water penetration.
They inhabit timbers that are more than one inch
thick. Old house borer beetles may be introduced
when modern infested wood is installed in existing
buildings. New wood may be infested in the
lumberyard, especially if it has not been kiln-dried.
The best prevention is to always use lumber that
has been kiln dried and, possibly, treated with a
borate spray.
Wood Repair
Repair work should be carefully planned to have
the least physical impact on historic wood. Any
cleaning should be undertaken using careful,
non-abrasive techniques. High-pressure blasting
using either water or abrasives is very damaging
and should never be used. If the exterior woodwork
requires painting or caulking, this will serve as
its primary protection from weathering. Painted
surfaces should be well-maintained. In general,
use an alkyd primer coat and two coats of latex
finish paint on wood surfaces, according to the
manufacturers’ instructions.
As with all historic material, damaged sections
should be replaced in-kind to match the historic
in all visual and physical qualities. Rotted wood
should be removed and replaced, especially if it
is structural. It is usually not necessary, however,
to remove an entire wood element that has limited
areas of rot. The deteriorated portion of the wood
element can be selectively removed and a wood
dutchman installed as a patch in the original
wood feature. For structural elements, a structural
engineer should be consulted to determine the
nature and extent of the repair required. In areas
of significant or ornamental wood elements,
commercially available epoxy consolidants can
be used to give strength to the existing wood.
Consolidants can also eliminate the need to remove
original historic wood elements.
Decay and Infestation Prevention and
Remediation
Remove invasive plants on or near wood and
address fungus or insect infestation problems
promptly. The best prevention of termite infestation
is to avoid direct contact between wood and the
ground and eliminate building water penetration.
Mulch piled against building foundations attracts
termites and should be pulled back from the
walls. Likewise, raised landscape beds that come
in contact with a building are problematic. Beetle
infestations can be prevented by preventing
moisture penetration, repairing deteriorated wood
features, and removing fungal growth. Carpenter
ants can be controlled with soil-applied fumigants
applied along the perimeter of the building. In the
case of carpenter bees, professional pest control
John Milner Associates • October 2009 • Chapter 9 • Building Guidelines • 296