I have a 500sqft uninsulated garage that shares an attic with the 400sqft main floor in my house. the attic only has insulation over the main room. If I insulate the rest of the attic will it help insulate the main floor? Or should I instead insulate the the crawlspace thats underneth the main floor better? I was thinking of adding those plastic bats that are designed for foundations ect. Some of the bats stuffed in and around the sill plate are missing or falling down. not to mention my gas furnace is loacted in the crawl space with all the forced air ducts. Would should I do first that will be the most effective?