How To Install a Deadbolt Lock

There are two types of deadbolt locks—externally mounted and internally mounted. The external deadbolt is much easier to install than the internal; however, it offers less security. An internal deadbolt, because of the tougher hardware and the long bolt also provides better security than a typical lockset that is standard for exterior doors.

This article describes how to install a deadbolt in a door that does not already have a deadbolt. If you are replacing a deadbolt that has already been installed in the door, refer to our article on replacing a deadbolt.

When buying a deadbolt, there may be two choices for keying. A double-cylinder lock offers extra security because a key is required on both sides of the door. If your door has a window and a home intruder breaks it, the keyed lock will prevent them from reaching in and unlocking the door. However, during an emergency this type of lock can be dangerous. If the key cannot be found and people can’t get out, the hazard is obvious. Some communities have restrictions against the use of such locks, check with your local building department. If you install a keyed lock, always keep the key in the same place and make sure that everyone in the family can easily access it.

Caution: Please read our safety information before attempting any installation or repairs.

When preparing to install a deadbolt lock, first check the area on the door and the jamb in which you’re going to install the deadbolt. You should locate the lock 6 to 12 inches above or at least 6 inches below the lockset. Determine if there are any impediments to installation in the door or jamb before beginning the installation.

The deadbolt will contain a template calibrated for different sized doors. Tape the template in place on the door and use a combination square to square it with the door. Mark the cut areas and location for the screw holes and remove the template.

Use a hole saw to cut the opening for the lock. Centering the hole saw on the cut area on the face of the door, start drilling and stop when the pilot bit comes through the back of the door. Remove the hole saw and finish drilling from the rear of the door by aligning the pilot bit with the pilot hole. Before cutting, make sure the hole saw matches up correctly with the opposing hole. This will ensure that the cuts coincide while avoiding damage to the face of the door.

Use a spade bit to drill the bolt hole into the edge of the door. Check the size by reviewing the instructions that came with the lockset. Carefully align the drill, keeping it level and square when making this hole. Misalignment can damage the door or make the deadbolt difficult to operate.

Place the bolt into the hole and trace the faceplate. Remove the faceplate and bolt and carefully mortise the area for the plate so that it fits flush with the edge of the door. After drilling pilot holes, secure the bolt to the door with screws.

Install the lock, cylinder and thumb plate, by first fitting the exterior section in place. When doing this, make sure the writing is upright. Then put the interior half in place, joining the two and aligning the screw holes. Anchor the deadbolt with screws.

To determine the location for the deadbolt hole in the doorjamb, cover the end of the bolt with paint, close the door and turn the deadbolt several times to mark the jamb. Open the door and mark the outline of the bolt. Using a spade bit, drill the hole into the doorjamb, deep enough for the bolt. Before going to the next step, double check the depth and size of the bolt hole by closing the door and turning the bolt into the hole numerous times. Adjust as needed.

Finally, place the strike plate over the bolt hole and, using a utility knife, score the plate’s outline. In order to make the strike plate lie flush within the jamb, you’ll need to mortise the area deep enough to accommodate the thickness of the strike plate. Once that is done, drill pilot holes for the entire length of the strike plate screws. Install the strike plate, close the door and test the deadbolt.

Note: While there is some room for error, precision is important. When installing the deadbolt lock, carefully measure and recheck before drilling holes. It is important to keep the drill level and square to the door. Use of a small level and carpenter's square will help with these steps.