Fixing a door threshold requires two people working together. Once the decision has been made about the door threshold (usually based on the fact the floor is left clear while the benefits of a threshold are still enjoyed) and the appropriate threshold obtained, fixing it is heavy work but quite simple.
The only tools you will need will likely be a screwdriver or two.
Step 1 - Check the Threshold
Present the threshold to the underside of the door and make sure it does not restrict the movement of the door and is long enough for the bottom of the door but not too long to prevent the door from closing properly.
Step 2 - Remove the Door
To fit the door threshold, it is necessary to remove the door. With an open hinge, it is sometimes possible to lift the door off the hinges. If the hinges have removable pins, the pins can be removed and the door removed. It is important to make sure you do not damage the hinges during this process. If the hinges are sealed, then you have to unscrew the hinges from (usually) the doorpost.
To do this right, support the door underneath so it can’t fall downwards or outwards – which is why two people are necessary. It is probably better to remove all but one screw from each of the hinges and then remove the final screws, starting at the bottom of the door and then move the door away from the post.
Step 3 - Check the Door
The bottom edges of doors are seldom painted, and you should check to ensure the wood is still sound. A common problem with doors is the bottom edge gets damp and starts to rot. If the door is sound and not painted, it would be wise to paint it now.
Step 4 - Fit the Threshold
Most door thresholds are fitted using short screws in pre-punched holes, and none of these holes should be too close to the edge of the door, so they don't cause a split. It would help if you fit the threshold, so it's centered on the door bottom.
Step 5 - Re-Fit the Door
Putting the door back is the reverse procedure of removing it. The hinges will be quite vulnerable, so it is important to make sure you do not damage them. The hinges with removable pins are particularly vulnerable, and you should not try to pin one hinge and use that to locate the others – that way, you will almost certainly distort the pinned hinge. Replacing the sealed hinges is also difficult, but usually, the hinges are fitted into recesses cut into the doorpost, so as long as the door is properly supported, it should not be too difficult.
Step 6 - Test
Once the door is re-hung, it should be tested to ensure the threshold is not restricting its movement and is not preventing it from opening and closing properly.
Door thresholds leave a clear run and are especially useful if wheeled items regularly move through the door. They might be a little more difficult to fit but worth the effort.