Where to Apply Caulk in a House

Exterior Trim and Siding:  Caulk all joints around window and door frames, don't forget to caulk under window sills.  Also caulk joints between siding and other trim strips or battens, such as corner molding, along eaves and gable ends, and between siding and base trim.  Use paintable, acrylic caulk for general purpose work.

Entry points:  Plug holes where pipes or wires enter the house.  Fill large hole with expandable foam.  smaller gaps can be filled with acrylic caulk or silicone seal.  When sealing around hose bibbs or bathroom doorways, squeeze tubes are usually easier to handle than a caulk gun.  Use extreme care around electrical work.

Foundation areas:  Fill gaps between the siding and foundation of your home.  Fill deep cracks with closed-cell foam backer strips or backer rope, then apply a high-grade masking caulk.  also caulk between the foundation wall and the mud sill if possible.  This step is done from the inside of a crawlspace or basement in most cases.  Use polyurethane caulk for this work.

Exterior wall-mounted vents:  Dryer vents, exhaust vents and other wall-mounted vents should be caulked.  Instead of running a bead of caulk around the outside of the vent, remove the vent, caulk around the opening in the wall and then reinstall the vent.  Wipe off any remnants with a rag.

Attic areas:  Seal joints between wallboard and the top plate of the wall; extend short beads of molding paste along both sides of the joist bottoms where they cross the joint.  Seal joints or gaps where vent pipes, ductwork, recessed bathroom fixtures and other areas exit through the ceiling.