The preceding description of a window repair job focused on
a unit which was operationally sound. Many windows will show
some additional degree of physical deterioration, especially
in the vulnerable areas mentioned earlier, but even badly damaged
windows can be repaired using simple processes. Partially decayed
wood can be waterproofed, patched, built-up, or consolidated
and then painted to achieve a sound condition, good appearance,
and greatly extended life.
Three techniques for repairing partially decayed or weathered
wood are discussed in this section, and all three can be accomplished
using products available at most hardware stores.
One established technique for repairing wood which is split,
checked or shows signs of rot, is to:
- dry the wood,
- treat decayed areas with a fungicide,
- waterproof with two or three applications of boiled linseed
oil (applications every 24 hours),
- fill cracks and holes with putty, and
- after a "skin" forms on the putty, paint the
Care should be taken with the use of fungicide which is toxic.
Follow the manufacturers' directions and use only on areas which
will be painted. When using any technique of building up or
patching a flat surface, the finished surface should be sloped
slightly to carry water away from the window and not allow it
to puddle. Caulking of the joints between the sill and the jamb
will help reduce further water penetration.
When sills or other members exhibit surface weathering they
may also be built-up using wood putties or homemade mixtures
such as sawdust and resorcinol glue, or whiting and varnish.
These mixtures can be built up in successive layers, then sanded,
primed, and painted. The same caution about proper slope for
flat surfaces applies to this technique.
Wood may also be strengthened and stabilized by consolidation,
using semirigid epoxies, which saturate the porous decayed wood
and then harden. The surface of the consolidated wood can then
be filled with a semirigid epoxy patching compound, sanded and
painted. Epoxy patching compounds can be used to build up missing
sections or decayed ends of members. Profiles can be duplicated
using hand molds, which are created by pressing a ball of patching
compound over a sound section of the profile which has been
rubbed with butcher's wax. This can be a very efficient technique
where there are many typical repairs to be done. The process
has been widely used and proven in marine applications; and
proprietary products are available at hardware and marine supply
stores. Although epoxy materials may be comparatively expensive,
they hold the promise of being among the most durable and long
lasting materials available for wood repair. More information
on epoxies can be found in the publication "Epoxies for
Wood Repairs in Historic Buildings," cited in the bibliography.
Any of the three techniques discussed can stabilize and restore
the appearance of the window unit. There are times, however,
when the degree of deterioration is so advanced that stabilization
is impractical, and the only way to retain some of the original
fabric is to replace damaged parts.