When preparing for a replacement door knocker installation, be sure to check the bolt center dimension of the existing door knocker before buying a replacement.
A replacement door knocker installation that is a through the door mounting method, the bolt center dimension has added meaning. You will probably want to use the same drilled holes that are already in the door. If so you will have to find a new door knocker with the same bolt center dimension as the previous one.
The bolt center dimension is the measurement from the center of one bolt hole to the center of the other bolt hole. We have shown this dimension on our door knocker comparison page.
The new door knocker must match the old door knocker at this dimension or your new door knocker will not fit the existing holes.
There are no industry standards regarding the bolt center dimension or the size hardware to be used. These are left to the manufacturers discretion. They are usually dependent on the shape and style of the door knocker itself.
At times it can be difficult to find an exact match. Sometimes you have to settle for getting your replacement door knocker as close as you can to the original. Then you may make an adjustment by enlarging the holes in the door or drilling an new hole and using one of the old ones. In these cases something needs to be done with the inside of the door to cover up the old or enlarged holes.
If the holes are enlarged they may be covered by using larger washers on the inside to cover the larger hole. If a third hole was needed the old one will need to be filled in.
The best bet is to find a replacement door knocker with the same bolt center dimension as the original one if possible.
