Darin, I agree with CDJr on the air infiltration. I always insist that people address this first before adding insulation, especially in walls. I know you said your attic has insulation but check to see if there are gaps or voids around lighting fixtures, chimneys, bathroom fans etc. Wire/plumbing runs can be sealed with spray foam, larger gaps can be filled with fiberglass batt. Do the same thing in your basement, garage, exterior. Seal around the switches/outlets on exterior walls and around your attic access door. Also check for drafts around exterior doors. Your attic should feel very cold in this weather. If not, you may need to add insulation there also but def. address the air infiltration first. Let me know if you need any supplies although all this stuff is available at the big box stores
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