No matter where you live or how old your home is, you will need to make it a point each year to ensure it’s ready for winter weather.And one of the easiest and most effective ways to do so is by making sure your exterior doors are thoroughly sealed against wind, rain, snow, and other outdoor elements. 

So the next, weather stripping is the best choice to seal a door gap.

It’s easy to install and doesn’t require any specialized tools and doesn’t require move the door from the door frame.

Firstly, you can see various weatherstripping on some website or the store,you can see many such as vinyl coated strips, foam or dense seals, just find available weather strip is ok.

Secondly, no matter what you choose, you need to cut it ensure it’s full length can along with entire the length of the door.

Third, cleaning the door frame and make it dry completely, then track the weatherstrip into place. Sometimes, some weatherstrip may also with adhesive backing that can help hold it in place. After finished install, open and close your door a few times to make sure it snug fit within the door frame and without any difficult to open and close.