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SEALANTS, GROUT & JOINTS

Gap Around a Window Frame

Gaps around window frames may be caused by shrinkage, poor fitting, failed sealant, frame movement or deteriorated exterior joints.

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Fix leaks, movement and moisture before resealing or regrouting

Wear gloves and eye protection. Stop if there is hidden water damage, persistent mould, structural movement or a safety-critical service penetration.

MOST LIKELY CAUSES

Start with these

Old sealant failed The bead has cracked or pulled away.
Frame movement Expansion and contraction open the joint.
Poor original fitting The gap may be too large or uneven.
Exterior weathering UV and rain degrade external sealant.
◫ Symptom variations Match the exact failure pattern and location. ⌄
  • Visible gap
  • Draught
  • Water staining
  • Sealant cracking
  • Noise around frame
✓ Quick checks Simple checks before removing material. ⌄
  1. Check for leaks, damp or movement.
  2. Identify the existing sealant or grout type.
  3. Remove only failed material.
  4. Clean and dry the joint thoroughly.
  5. Choose a compatible flexible product.
1 Step 1 — Identify whether the gap is internal or external Remove failed material fully and use products suited to the joint, movement and moisture level. ⌄

Use a sealant suited to the location and substrate.

2 Step 2 — Remove failed material Remove failed material fully and use products suited to the joint, movement and moisture level. ⌄

Cut away loose sealant and clean the joint.

3 Step 3 — Fill and seal correctly Remove failed material fully and use products suited to the joint, movement and moisture level. ⌄

Use backing material for deep gaps and apply a neat flexible bead.

⌁ Common causes explained Why sealants, grout and joints fail. ⌄

Gaps around window frames may be caused by shrinkage, poor fitting, failed sealant, frame movement or deteriorated exterior joints.

⌘ Advanced diagnostics Further checks for recurring failures. ⌄
  • Check frame fixings.
  • Inspect external drainage paths.
  • Use low-expansion foam only where suitable.
  • Check for damp penetration.
  • Confirm movement compatibility.
▣ Parts and materials needed Common materials linked to this repair. ⌄
  • Interior acrylic sealant
  • Exterior frame sealant
  • Backing rod
  • Low-expansion foam
  • Sealant gun
! When to call a professional Conditions that should end basic DIY work. ⌄
  • Water is leaking into walls or floors.
  • The joint keeps opening because of movement.
  • Mould or damp is widespread.
  • An unvented cylinder, flue or fire-stopping joint is involved.
  • Tiles or fittings are loose or unstable.
? Frequently asked questions Common sealing and grouting questions. ⌄

Can new silicone be applied over old silicone?

No. Remove the old material and residue first for a reliable bond.

Should corners be grouted or sealed?

Changes of plane usually perform better with a suitable flexible sealant.