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DRAUGHTS & SEALS

Cold Air Through Keyhole

Air can pass directly through older keyholes or poorly covered cylinders. A suitable cover can reduce draughts while keeping the lock usable.

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Do not block required ventilation or drainage

Some gaps, vents and drainage slots are intentional. Fire doors, external doors and emergency windows may also have specific sealing requirements.

MOST LIKELY CAUSES

Start with the exact air or water path

Open keyway Older mortice locks have a direct air path.
Missing escutcheon cover No flap or rotating cover shields the opening.
Poorly fitted hardware Gaps exist around the cylinder or lock plate.
Strong pressure difference Wind drives air through small openings.
◫ Symptom variations Match the draught, gap or seal pattern. ⌄
  • Cold spot at lock
  • Whistling in wind
  • Light visible through keyhole
  • Draught stops when covered by hand
  • Condensation near lock
✓ Quick checks Safe checks before replacing seals. ⌄
  1. Confirm the airflow comes through the keyhole, not around the door.
  2. Inspect both sides of the escutcheon.
  3. Check the lock operates freely.
  4. Look for gaps around the cylinder.
  5. Do not insert material into the lock.
Important: Find the exact leak path first. Replacing the wrong seal can make closing harder without fixing the fault.
1 Step 1 — Confirm the exact air path Make the smallest safe correction and retest. ⌄

Test the keyhole and surrounding plate separately.

2 Step 2 — Fit a suitable cover Make the smallest safe correction and retest. ⌄

Use a flap, rotating escutcheon or brush-backed cover compatible with the lock.

3 Step 3 — Seal surrounding gaps carefully Make the smallest safe correction and retest. ⌄

Do not obstruct moving parts or drainage.

⌁ Why the problem happens How compression, alignment and weathering affect sealing. ⌄

Traditional locks can form a small tunnel through the door. Wind pressure makes even a tiny opening noticeable.

⌘ Advanced checks Further diagnosis for persistent sealing faults. ⌄
  1. Check cylinder escutcheon fit.
  2. Inspect lock-case alignment.
  3. Assess door perimeter sealing.
  4. Check external weather shield.
  5. Confirm fire-door requirements.
◇ Tools and information needed Useful items for accurate checks. ⌄
  • Screwdriver
  • Tape measure
  • Torch
  • Suitable escutcheon
  • Pencil
▣ Parts or improvements that may help Common sealing products linked to this problem. ⌄
  • Keyhole cover
  • Escutcheon
  • Cylinder guard
  • Brush seal
  • Fixing screws
! When to call a professional Conditions that should end basic DIY diagnosis. ⌄
  • The door is a fire door.
  • The lock is part of certified security hardware.
  • There are signs of forced entry.
  • The cylinder is loose.
  • The lock operation changes after fitting a cover.
? Frequently asked questions Common draught and seal questions. ⌄

Can I block the keyhole with foam?

No. Loose material can enter and damage the lock.

Will a flap cover stop all draught?

It should reduce it significantly, though not always completely.

Can I use any escutcheon?

It must suit the lock type and allow full key movement.