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DRAUGHTS & SEALS

Draught Around a Window

A draught around a window may come from failed gaskets, dropped hinges, poor locking compression, frame sealant gaps or an open vent.

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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

Worn gasket The rubber seal has flattened, split or shrunk.
Dropped hinge The sash no longer compresses evenly.
Misaligned keeps Locking cams do not pull the sash tight.
Frame perimeter gap Sealant between frame and wall has failed.
◫ Symptom variations Match the draught, gap or seal pattern. ⌄
  • Cold air at one corner
  • Whistling in wind
  • Condensation near the leak
  • Handle closes but sash feels loose
  • Draught appears around trim
✓ Quick checks Safe checks before replacing seals. ⌄
  1. Confirm trickle vents are closed if appropriate.
  2. Run a tissue around the sash and frame.
  3. Inspect gaskets for gaps or shrinkage.
  4. Check whether the sash is square.
  5. Look for cracked external sealant.
Important: Find the exact leak path first. Replacing the wrong seal can make closing harder without fixing the fault.
1 Step 1 — Separate sash leaks from frame leaks Make the smallest safe correction and retest. ⌄

Test the opening joint and frame perimeter independently.

2 Step 2 — Restore sash alignment and compression Make the smallest safe correction and retest. ⌄

Adjust hinges or keeps where suitable.

3 Step 3 — Replace failed seals Make the smallest safe correction and retest. ⌄

Fit the correct gasket and reseal frame gaps externally.

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

Window seals rely on even pressure from the locking system. A small hinge drop can leave one corner under-compressed.

⌘ Advanced checks Further diagnosis for persistent sealing faults. ⌄
  1. Check cam adjustment.
  2. Measure gasket profile.
  3. Inspect frame drainage slots.
  4. Check friction hinges.
  5. Assess perimeter sealant from outside.
◇ Tools and information needed Useful items for accurate checks. ⌄
  • Tissue
  • Torch
  • Allen keys
  • Tape measure
  • Sealant tools
▣ Parts or improvements that may help Common sealing products linked to this problem. ⌄
  • Window gasket
  • Friction hinges
  • Keeps
  • Exterior sealant
  • Trickle vent cover
! When to call a professional Conditions that should end basic DIY diagnosis. ⌄
  • The window is high-level.
  • The frame is loose or distorted.
  • The glass unit is moving.
  • Water ingress is present.
  • The sash cannot be locked securely.
? Frequently asked questions Common draught and seal questions. ⌄

Can trickle vents cause a draught?

Yes, by design, although damaged vents may leak excessively.

Why is one corner worse?

That often points to hinge drop or poor keep alignment.

Can I silicone the opening joint shut?

No. That can prevent the window opening and trap moisture.