Some people don't button up the house until caulking fails, wind
whistles in, and the first eye-popping utility bill of the
winter lands in the mailbox. But you can cut fuel costs, stop
air leaks, and prevent damage from water, ice and snow by
sealing the house before winter hits.  Here are some preventive
maintenance tips for siding, windows and doors to help prepare
for the big chill:  Caulking. This quick fix will bridge many
minor gaps in wood and masonry. To make a repair last, first dig
out old caulk, let the crack dry, and brush out debris. Then
apply a liberal bead of flexible, exterior-grade caulk, such as
silicone. Once silicone sets up you can easily trim off any
excess to create a neat finish.  Fixing split clapboards and
shakes. Fix a small split by prying open the crack slightly and
coating the mating edges with waterproof glue. Don't risk
another split by nailing a sliver. Instead, wedge it in place
with a board like a 2-by-4 angled down to the ground until the
glue sets.  Filling damaged wood.