Far better opportunities to reduce air leaks in a house are found in the attic. Typical culprits are chimney and plumbing chases. They can actually have gaps that add up to several square feet. Any kind of ceiling discontinuity is also suspect. Multilevel, sloped and plank ceilings can produce 4 sq.
Recessed lighting can also spew huge volumes of warm air into the attic.
Finally, smaller air-sealing opportunities, such as drywall gaps and wiring penetrations, lurk along the tops of every interior wall. Seal every hole you find as tight as a tire. Use sheet metal, expandable foam and caulk. And don't forget to close the fireplace damper if you haveone. Every bit of exfiltration you fix will produce an instant reduction of drafts throughout the living areas of your home.