Weather-Stripping the Bottom of The Door (A bit trickier)
There are four main ways that doors are sealed on the bottom. These are: door sweeps, door shoes, gasketted thresholds and interlocking thresholds.
Door sweeps are fastened to the bottom of the door They may be attached to the inside or to the outside of the door. A sturdy mounting strip is attached to the bottom of the door and a brush or plastic strip touches the floor, or buts against the threshold. You don’t have to remove a door from its hinges in order to install a door sweep. An uneven floor surface or gap could make installing a floor sweep difficult. A door sweep may have to be replaced every couple of years in some cases due to wear and tear. So, if you do have a door sweep, make sure to check it every year at least to see if it needs replacement.
Door shoes are foam or vinyl gaskets which are applied to the bottom edge of a door by nailing or screwing the shoe in place. Door shoes tend to last longer than sweeps do, they have a five year life expectancy. However they require that the door be removed from its hinges in order to install them.
A gasketted threshold is applied not to the door, but rather, it is applied to the threshold. The gasketted threshold provides a vinyl hump at the threshold which is compressed when the door closes thus creating a good seal. You must measure carefully before installing so that you may be sure that the gasket makes good contact with the door, and provides a tight seal. An even space beneath the door would be needed.
An interlocking threshold combines a door shoe (applied to the door) and a metal attachment (applied at the threshold and which increases the effectiveness of the door shoe). This is weather-stripping technique requires the most skill in installing.