Fitting a door number or door numbers is one of the easier DIY jobs.
There are 2 types of door number, those that stick on and those that are screwed to the door. Diy Doctor has seen, and used, another type which has bolts on the reverse which slot through purpose drilled holes in the door. These are used in busy City areas sometimes to stop theft but are very uncommon in a domestic situation.
Firstly the Screw on Type
Place the door numbers where you want them. There are no rules for this and if it looks right, it is right. Usually people prefer to have the number or numbers in the middle of the door so take a tape measure and mark the centre point of the door at the height you want the number.
If your house is a double or treble digit number, place a spirit level on this mark and mark a short faint line across an equal distance from the centre point. The bottom of the numbers can sit on this line and you can be sure it will be level.
Place the numbers on the line and mark the screwholes. Using a small drill bit, drill pilot holes for the screws. Make sure the drill bit is smaller than the diameter of the screws. The need for a pilot hole is that most door number and indeed, most door furniture of all types, uses small brass screws, even hinges. Because brass is not the strongest of metals, if the timber is particularly solid, as with Oak front doors for example, it is easy for the brass screw to snap off leaving the threaded section in the door. This is next to possible to remove without damaging the door so 2 minutes spent making a pilot hole can save you a whole day.
Screw the numbers to the door and rub out any remaining pencil lines.
Next the Adhesive Numbers
Sticking numbers on doors is a very easy job but because of the effectiveness of the adhesive you only get one chance to get it right! Make sure, using the method above, that you have marked the exact position you want the numbers.
Peel off the backing strip and apply the numbers carefully from one side, almost "rolling" them onto the surface. Once they are stuck, they are stuck but if you do get into difficulties and have placed one on incorrectly it can be removed by sliding (some force is necessary) a wide bladed paint scraper up behind the number. This may leave some adhesive on the door and this needs to be wiped off using a rag dipped in solvent thinners or white spirit.
The number can then be re-stuck using a strong adhesive.