Install a Deadbolt

Goal

Install a deadbolt lock on an existing door, either as new addition or as replacement of existing. Most residential burglary entries come through doors without deadbolts; this is high-value security work.

Prerequisites

• Deadbolt kit (single or double cylinder)
• Cordless drill + 2-1/8" hole saw + 1" Forstner bit
• Chisel + hammer
• Tape measure + center punch
• Screwdriver
• Door template (usually included with deadbolt)
• 30-60 minutes per installation

When to install

Always recommend if:

• Door has only a knob lock (not secure)
• Door has only a chain (not secure)
• Existing deadbolt is loose, worn, or damaged

Don't install on:

• Bedroom doors (egress code; can't lock from inside)
• Bathroom doors (egress; privacy locks only)
• Sliding glass doors (use different security)
• Garage entry doors (typically existing deadbolt; check first)

Procedure

Step 1: Plan the installation

1. Measure door thickness (most: 1-3/8" or 1-3/4")
2. Locate the lock position:
   • 6-12 inches above existing handle/knob lock
   • Even with the latch height OR slightly above
3. Mark center of door for cross-bore (2-1/8" hole)
4. Mark center of door edge for edge-bore (1" hole)
5. Use template to align everything

Step 2: Bore the cross-bore (door face)

1. Center punch the mark on door face
2. Drill pilot hole through both sides of door
3. From OUTSIDE of door, drill halfway through with 2-1/8" hole saw
4. From INSIDE of door, complete the bore
5. (Drilling halfway from each side prevents splintering)

Step 3: Bore the edge-bore (door edge)

1. Center punch the mark on door edge (at center of cross-bore)
2. Drill 1" hole through edge to meet cross-bore
3. Should connect cleanly to cross-bore

Step 4: Install the latch (bolt mechanism)

1. Insert latch into edge bore
2. Faceplate should sit flush on door edge
3. Mark perimeter of faceplate
4. Chisel out a recess for faceplate to sit flush
5. Drill pilot holes for faceplate screws
6. Screw latch into place

Step 5: Install the cylinder + thumbturn

1. From outside: insert exterior cylinder into cross-bore
2. Engage the cylinder's tail piece with the latch mechanism
3. From inside: insert interior thumbturn
4. Bolt the two sides together with provided screws
5. Test the bolt: throws cleanly when key turned or thumbturn rotated

Step 6: Install strike plate

1. With door closed, mark where bolt hits the frame
2. Mark center of bolt impression
3. Drill 1" hole at the mark, 1" deep (allows bolt to extend fully)
4. Position strike plate over hole
5. Mark perimeter; chisel recess for flush mounting
6. USE 3-INCH SCREWS (longer than included short screws) for kick-resistance
7. Screw strike plate in

Step 7: Test operation

1. Open + close door
2. Test bolt extension: bolt extends 1" minimum into frame
3. Test key from outside: smooth operation
4. Test thumbturn from inside
5. Verify door closes fully with bolt extended

Step 8: Customer walkthrough

1. Demonstrate operation
2. Provide keys (2-3 minimum)
3. Explain warranty (typically 1 year labor + manufacturer)
4. Recommend annual lubrication
5. Suggest additional security measures if appropriate

Single vs double cylinder

Single cylinder (most common):

• Key from outside; thumbturn from inside
• Faster egress in emergency
• Less secure if window near door (can be reached + turned)

Double cylinder:

• Key from both sides
• More secure (no thumbturn to break window + reach)
• ILLEGAL in some jurisdictions (egress concern)
• Don't install on bedrooms; emergency exit risk

Check local code before installing double cylinder.

Door thickness considerations

• 1-3/8" door: standard residential interior + many exterior
• 1-3/4" door: heavier exterior doors
• Custom (2"+): heavy/security doors

Standard deadbolts adjust to fit; verify before purchase.

Backset

• 2-3/8" backset: distance from door edge to center of cross-bore (most common)
• 2-3/4" backset: alternative
• Adjustable backset latches accommodate either

Match the latch to the existing bore OR the new template.

Strike plate quality

Strike plates dramatically affect kick-resistance:

• Cheap strike plate: 2-screw, pulled out by single kick
• Standard strike: 4-screw, OK but still soft pine jamb
• Security strike: heavy gauge, 6+ screws, extended into stud
• Stud-mounted reinforcement: bolted through framing

Upgrade matters: 3-inch screws into framing make a huge difference.

Common pitfalls

• Wrong hole saw size: 2-1/8" standard for cross-bore; many deadbolts are this; some specialty larger
• Off-center holes: lock doesn't seat properly
• Bore depth too shallow: bolt doesn't extend into frame fully (insecure)
• Strike plate too tight: door doesn't latch
• Short screws on strike plate: kickable
• Forgetting frame inspection: rotten or loose frame won't hold strike
• Wrong cylinder direction: tail piece engages wrong way

Combining with knob lock

When adding deadbolt to a door with existing knob:

• Both should be keyed alike if same key (less hassle)
• Or keyed differently (different security level)
• Customer decides; communicate clearly

If customer wants both same key: bring locksmith re-keying kit OR keyed-alike products.

Security recommendations to discuss

• 3-inch screws on strike plate (always)
• Long screws on door hinges (matching reinforcement)
• Security strike plates
• Deadbolt + knob lock (multiple defense layers)
• High-security cylinder (Medeco, Mul-T-Lock) for premium customers
• Smart lock conversion for tech-forward customers
• Window film + window locks (related security)

Code references

• IRC R311 (egress doors must have lock operable from inside without tools or key)
• Local building codes (some restrict double-cylinder deadbolts)
• ANSI/BHMA grade ratings (Grade 1 commercial, Grade 2 residential heavy, Grade 3 residential standard)

References

• ANSI/BHMA A156.36 (deadbolts)
• ALOA installation standards
• Manuall internal: Lock Types + Mechanisms Reference, Rekey + Lock Change SOP