How to Install a Deadbolt Lock on a New Door: DIY Guide

A deadbolt is the most important lock on your exterior door — it's what stands between your home and a potential intruder. Unlike spring-bolt locks (knob locks), a deadbolt can't be pushed back with a credit card or pried open with a screwdriver. Installing one yourself is a very achievable DIY project that takes about 30–60 minutes with the right tools.

Choosing the Right Deadbolt

Single vs Double Cylinder

A single-cylinder deadbolt has a key cylinder on the outside and a thumb turn on the inside. This is the most common type for residential use. You can always unlock it from inside without a key, which is critical for emergency egress.

A double-cylinder deadbolt requires a key on both sides. These are used on doors with glass panels to prevent an intruder from breaking the glass and reaching in to turn the thumb turn. However, many building codes restrict or prohibit double-cylinder deadbolts because they can trap occupants during a fire. Check your local codes before installing one.

Lock Grades Explained

The American National Standards Institute (ANSI) rates locks in three grades:

• Grade 1: Commercial-grade. Withstands 10 strikes of 75 pounds of force. Best security available. Brands: Medeco, Schlage B660.
• Grade 2: Heavy-duty residential. Withstands 5 strikes of 75 pounds. Best value for homes. Brands: Schlage B60N, Kwikset 980.
• Grade 3: Basic residential. Withstands 2 strikes of 75 pounds. Adequate for interior doors. Most budget locks fall here.

For exterior doors, always use Grade 2 or better. The price difference between Grade 2 and Grade 3 is often less than $15 — a trivial cost for significantly better security.

Tools and Materials Required

• Deadbolt lock set
• 2-1/8 inch hole saw (for the cross-bore)
• 1-inch spade bit or Forstner bit (for the edge bore)
• Drill/driver
• 1-inch wood chisel
• Hammer
• Tape measure and pencil
• Utility knife
• Phillips and flathead screwdrivers

Marking and Measuring the Door

Most deadbolts are installed 6–12 inches above the existing knob lock, typically centered at 44 inches from the floor (with the knob at 36 inches). Use the paper template included with your deadbolt — tape it to the door at the correct height, wrapping it around the edge.

Mark the center of the cross-bore hole on the door face and the center of the edge bore on the door edge. Double-check that both marks align according to the template. The standard backset (distance from the edge of the door to the center of the cross-bore) is either 2-3/8 inches or 2-3/4 inches. Most deadbolts include an adjustable latch that fits both.

Drilling the Holes

Cross-Bore Hole (Face of Door)

Using a 2-1/8 inch hole saw, drill from the exterior side of the door. Apply steady, even pressure. When the pilot bit just pokes through the other side, stop. Go to the interior side and complete the hole from that direction. This prevents splintering on the exit side, which is especially important on stained or finished doors.

Edge Bore Hole

Using a 1-inch spade bit, drill straight into the edge of the door at your marked center point. Drill until you intersect the cross-bore hole. Keep the drill perfectly perpendicular to the door edge — even a slight angle will cause the bolt to bind. A drill guide or a square held against the door edge can help you stay straight.

Installing the Deadbolt Mechanism

1. Insert the bolt assembly. Slide the bolt assembly into the edge bore with the bolt face flush against the door edge. The tapered side of the bolt should face the direction the door closes.
2. Trace the bolt plate. Using a utility knife, score around the bolt faceplate. Remove the bolt and chisel a mortise just deep enough for the plate to sit flush with the door edge.
3. Secure the bolt plate. Reinsert the bolt assembly and screw the faceplate into the mortise.
4. Install the exterior cylinder. From outside, insert the key cylinder through the cross-bore so the tailpiece (the bar on the back) passes through the slot in the bolt assembly.
5. Attach the interior thumb turn. Place the interior assembly over the tailpiece and secure it to the exterior cylinder using the long mounting screws provided. Tighten evenly.
6. Test the lock. Turn the thumb turn and key to make sure the bolt extends and retracts smoothly.

Installing the Strike Plate

Mortising the Strike Plate

Close the door and extend the bolt to mark its position on the door jamb. Alternatively, coat the end of the bolt with lipstick or chalk for a precise mark. Center the strike plate over this mark. Trace around the plate with a utility knife and chisel a mortise for it. Also chisel or drill a recess for the bolt to fully extend into — usually 1 inch deep.

Door Frame Reinforcement

This is the most overlooked step in deadbolt installation, and arguably the most important. The standard short screws that come with most strike plates only reach the door jamb — they don't penetrate the structural framing behind it. Replace them with 3-inch screws that reach through the jamb and into the wall stud. This single upgrade makes your door exponentially harder to kick in. For even more security, install a reinforced strike plate (also called a security strike plate) with four 3-inch screws.

Testing and Adjusting

After installation, test the deadbolt thoroughly:

• Lock and unlock with the key from outside — it should turn smoothly without forcing
• Lock and unlock with the thumb turn from inside
• The bolt should extend at least 1 inch into the strike plate
• The door should close easily without the bolt scraping the strike plate

If the bolt doesn't align with the strike plate, you may need to enlarge the mortise or reposition the plate slightly. File the strike plate opening if the misalignment is minor (1/16 inch or less).

Common Problems and Fixes

• Bolt won't extend into strike plate: The most common cause is misalignment. Check that the door is hanging plumb and the strike plate is correctly positioned.
• Key is hard to turn: The cylinder may be slightly misaligned with the bolt tailpiece. Loosen the mounting screws, adjust the cylinder position, and retighten.
• Bolt binds or sticks: The edge bore may not be perfectly perpendicular. Apply graphite lubricant to the bolt. If the problem persists, enlarge the edge bore slightly with a round file.
• Door won't close after installation: The bolt faceplate may be protruding from the door edge. Deepen the mortise so the plate sits flush.

Frequently Asked Questions

Can I install a deadbolt on a hollow-core door? Technically yes, but it's not recommended. Hollow-core doors offer virtually no security — they can be punched through. Deadbolts should only be installed on solid-core or solid-wood exterior doors.

How far above the doorknob should a deadbolt be? The standard is 6 inches above the knob, but 6–12 inches is acceptable. This places the deadbolt at a comfortable height for daily use.

Do I need a deadbolt if I have a smart lock? Most smart locks replace the deadbolt — they are deadbolts with electronic controls. If your smart lock is a knob-only replacement, yes, you should still have a deadbolt for security.

Can I install a deadbolt on a metal door? Yes, but you'll need a metal-cutting hole saw and should use cutting oil. Some metal doors come pre-drilled for deadbolts. Check the manufacturer's instructions as some metal doors have reinforced areas specifically for lock installation.