Energy & Weatherproofing

How to Seal a Drafty Exterior Door

Improve an exterior door’s air seal by testing the perimeter, adjusting hardware and replacing worn weatherstripping.

Common symptoms

• Cold air around the perimeter
• Daylight visible at edges
• Noise or odour enters easily
• The threshold area feels cold

Likely causes

Start with the simplest observable cause and avoid replacing parts until the failure has been identified.

• Compressed weatherstripping
• Loose hinges
• An incorrect strike adjustment
• A worn door sweep
• A warped slab or frame

Tools and materials

• Screwdrivers
• Tape measure
• Replacement weatherstripping
• Door sweep
• Flashlight

Step-by-step procedure

1. Inspect the door in daylight and use a strip of paper to test compression around the closed perimeter.
2. Tighten hinge screws and confirm the door sits squarely before replacing seals.
3. Adjust the strike only enough to create uniform gasket compression without making the latch difficult to operate.
4. Remove a sample of existing weatherstripping and match its profile and mounting method.
5. Install new material without stretching it, and make tight corner joints.
6. Replace or adjust the sweep so it contacts the threshold without dragging excessively.
7. Retest the full perimeter and confirm the door latches and opens freely.

Common mistakes to avoid

• Adding thick seals before correcting hinge sag
• Stretching adhesive weatherstripping during installation
• Making the door difficult to latch
• Blocking threshold drainage

Verify the repair

Test the repaired component through several normal operating cycles. Watch, listen and feel for leaks, heat, movement, unusual noise or odour. Stop immediately if the condition worsens. Document the work and retain part numbers, receipts and manufacturer instructions for future maintenance.

When to call a professional

Use a door specialist for warped units, rotten frames, water intrusion, failed insulated glass or fire-rated assemblies.

Editorial note

This guide is written for general homeowner education. Building codes, product instructions, warranties, condominium rules and licensing requirements vary. The safest compliant method for your property always takes precedence.