|What is Standard Door Prep? For a door with a door knob (or Lever) with a deadbolt above, standard door prep is two 2 1/8" bore holes spaced 5 1/2" CC apart with 1" cross bores on the edge of the door - like the image to the left.|
Prepping a door for standard measurements is pretty easy to do, and it's much easier if you have a template as a guide. The template will keep your whole saw or drill bit in the right place and the right angle. You can purchase a template from hardware stores, but generally they will only allow you to do one bore hole at a time. If you need two bore holes for a door handle and keyed deadbolt above, you may just want to build your own template to get the holes spaced just right.
To start, get a peice of 3/4" plywood 18" or so tall and 8" wide. From the edge measure over and draw a line 3/4" of an inch from the edge. From that line you can measure over for your backset (2 3/8" or 2 3/4") and space them at 5 1/2" CC vertically. Once you have the center points marked out for your bore holes, drill a 2 1/8" bore hole in each location. Follow this process on another piece of plywood of the exact dimensions.
Tip: If you plase the center of the bottom bore hole at exactly 6" from the bottom of the template, it will make it easier to line things up on the door. We'll explain why in step 3.
|Now you'll need to cust a strip of 3/4" plywood the width of your door. Most interior doors are 1 3/8" while exterior doors are most commonly 1 3/4". You'll want to measure what you have to be sure. In this case, we had a 1 3/4" thick door so we cut a strip 1 3/4" thick and 18" tall. Now line up the measurement lines with your side pieces to mark the locations of the cross bores. These should be 1" diameter cross bores centered on the thickness of the door and lined up exactly with the 5 1/2" cc bore holes you made before. Once you have that piece prepped, attach the 3 pieces into a U shape using screws - as shown in the image to the left.|
|To prep your door, measure up 36" from the bottom of the door, and place the bottom bore centered on that mark. (36" inches from the bottom of the door is standard for the knob or lever to be mounted. Of course you can place it wherever you like). If you Followed our tip on step one, you can place the bottom of the template at 30" from the door bottom and you'll be set. Now use some C clamps or wood working clamps to secure the template solidly in place for drilling. Be sure the U shaped template is all the way on the door and that there is no gap top or bottom on the door edge.|
|Now drill each bore hole on one side of the door part of the way through the door. We recommend drilling from both sides so that you end up with cleaner holes. If you drill completely from one side, especially on a veneer door, you may end up with blowout and no one wants that. Some people use masking tape to cover the area where they will be drilling. The tape works well, but where we had the template wrapping the door, we didnt want the tape interfering with the template.|
|Now drill through the other side of the template to clean out the holes.|
|Next, you guessed it - drill out your 1" cross bores. Be sure to sweep up the floor or someone is bound to be upset with all of the saw dust you just made.|
Now remove the template and you have a door ready for drive in latches, and easily chiseled out for square corner latch faceplates. ou can also create a jig for rounding out the latch corners, but we'll cover that in a different article.