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Chimney

Vents smoke and gases — exposed to constant weather and heat

A chimney is a vertical structure that vents smoke and gases from fireplaces or boilers, extending above the roofline. It is exposed to constant weather and heat, making it prone to wear. Main parts include the stack (brick or stone structure), flue (inner passage for smoke), crown (top cement layer), flashing (seal between chimney and roof), and pot/cap (top section).

Common Damage

1. Cracked or Loose Brickwork

  • Bricks and mortar joints wear out over time
  • Caused by weather, frost, and age

2. Mortar Deterioration (Repointing Needed)

  • Mortar between bricks crumbles
  • Leads to instability and water ingress

3. Chimney Leaks

  • Water enters through cracked crown
  • Damaged flashing or porous brickwork

4. Flashing Failure

  • Lead flashing around chimney can crack, lift, or corrode
  • Very common cause of roof leaks

5. Chimney Crown Damage

  • The top cement layer can crack
  • Allows water to soak into the chimney

6. Flue Damage

  • Internal lining can crack or deteriorate
  • Dangerous because it affects ventilation and safety

7. Chimney Pot Damage

  • Pots can crack, lean, or fall off
  • Often due to wind or ageing

8. Leaning or Structural Movement

  • Chimney may tilt or separate from the house
  • Serious structural issue

9. Blockages

  • Birds' nests, debris, or soot buildup
  • Can cause poor airflow and smoke backing up

Repairs

minor Repairs

  • Repoint mortar joints
  • Replace a few bricks
  • Seal small cracks
  • Fit chimney cap or guard

moderate Repairs

  • Replace flashing
  • Repair or rebuild chimney crown
  • Install or repair flue liner
  • Replace chimney pot

major Repairs

  • Partial rebuild of chimney stack
  • Structural reinforcement
  • Fix leaning chimney

New Installation

When Replacement Is Needed

  • Severe structural damage
  • Leaning or unstable chimney
  • Extensive leaks
  • Removal and rebuild during renovation

Installation Steps

  1. Remove Old Chimney (if needed)

    • Carefully dismantle damaged structure

  2. Prepare Base

    • Ensure strong support from roof or ground
    • Reinforce structure if required

  3. Build Chimney Stack

    • Lay new bricks or blocks
    • Construct flue channel

  4. Install Flue Liner

    • Clay, metal, or concrete liner
    • Ensures safe airflow

  5. Add Flashing

    • Install lead flashing at roof junction
    • Prevent water ingress

  6. Form Chimney Crown

    • Cement top layer shaped to shed water

  7. Install Chimney Pot / Cap

    • Improves draft and keeps out rain/birds

Lifespan

Brick Chimney
50–100+ years (with maintenance)
Mortar
20–30 years before repointing
Flue Liner
15–30 years

Warning Signs

  • Crumbling mortar or loose bricks
  • Water leaks near chimney
  • Damp patches inside
  • Leaning chimney
  • Pieces falling off
  • Smoke not venting properly

Other Roofing Services

View all roof types

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