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Cavity Wall

Cavity Wall Insulation Removal: Complete Cost & Process Guide

When cavity wall insulation causes damp, it needs professional extraction. Understand removal costs (£2,000-£5,000), the extraction process, and whether removal or remediation is the right choice for your property.

Typical Cost Range
Complete cavity wall insulation extraction costs £2,000-£5,000 for a standard UK house depending on property size, insulation type, and wall construction. Includes extraction, disposal, and basic remediation.

Quick Cost Summary

£1,800 - £3,000
Small/Mid Terrace
2-3 bed | 50-70m² wall area
£2,500 - £4,000
Semi-Detached
3 bed | 80-100m² wall area
£3,500 - £5,500
Detached House
4 bed | 120-150m² wall area

When Cavity Wall Insulation Needs Removal

Not all problematic cavity wall insulation requires full removal. Consider extraction when:

Removal Recommended

  • • Penetrating damp on multiple walls
  • • Cavity bridging causing moisture transfer
  • • Wrong insulation type for property
  • • Installed in narrow cavities (under 50mm)
  • • High-exposure coastal/exposed locations
  • • Mould growth linked to insulation
  • • Failed repairs/remediation attempts

Repair May Suffice

  • • Isolated damp in one area only
  • • Issues with specific bricks/pointing
  • • Fixable wall tie or DPC problems
  • • Good cavities but installation defect
  • • Property not in high-exposure location
  • • Recent installation with warranty

Cavity Wall Insulation Extraction Cost Breakdown

1. Survey and Assessment (£200 - £450)

Borescope cavity inspection£150 - £300
Damp survey with moisture readings£200 - £400
Thermal imaging (optional)+£150 - £300

2. Extraction Labour (£1,500 - £3,500)

Cavity wall insulation extraction uses vacuum suction through drilled access holes. Cost depends on wall area and insulation type:

Drilling access holes (20-30 per wall)Included
Vacuum extraction equipment & labour£18 - £30/m²
Typical semi-detached (90m²)£1,620 - £2,700
Difficult extractions (bonded beads)+20% to +40%

3. Making Good & Finishing (£400 - £1,200)

Filling and matching drilled holes£8 - £15 per hole
Render patch repairs (if needed)£200 - £600
External painting/finishing£300 - £800

4. Waste Disposal (£150 - £400)

Insulation material disposal£100 - £250
Site cleaning and vacuum£50 - £150

Types of Cavity Wall Insulation & Extraction Difficulty

Polystyrene Beads

Easy

Free-flowing beads vacuum out easily. Most common type, straightforward extraction.

Extraction Success:

90-95% removal achievable

Cost Range:

£1,800 - £3,500 (standard property)

Mineral Wool/Fibre

Moderate

Blown fibre can clump and stick to cavity walls. May require higher suction power.

Extraction Success:

75-85% removal achievable

Cost Range:

£2,200 - £4,200 (standard property)

Bonded Beads/Foam

Difficult

Adhesive-bonded materials very hard to extract. May achieve only partial removal.

Extraction Success:

60-70% removal typical, complete removal may be impossible

Cost Range:

£3,000 - £6,000 (or may not be viable)

Extraction Limitations
No extraction method achieves 100% removal. Typically 80-95% of insulation can be extracted. Remaining material is usually insufficient to cause ongoing problems, but contractors should confirm this via post-extraction inspection.

The Extraction Process

1

Pre-Extraction Survey

Borescope inspection to identify insulation type, check cavity condition, and plan extraction hole positions.

2

Access Hole Drilling

20-40 holes drilled at strategic points (typically every 1-1.5m horizontally and vertically). Standard size: 22mm diameter.

3

Vacuum Extraction

Industrial vacuum system extracts insulation through access holes. Process takes 1-3 days depending on property size.

4

Post-Extraction Inspection

Borescope check confirms successful removal. Any remaining material assessed for potential issues.

5

Making Good

Access holes filled, matched to existing brickwork/render. External finish restored to match surrounding area.

6

Certification

Contractor provides completion certificate, before/after photos, and any warranty documentation.

After Extraction: Next Steps

Once cavity wall insulation is removed, you have three main options:

Leave Empty

Return cavities to original uninsulated state

Pros: No further issues, breathable walls
Cons: Higher heating costs, lower EPC

Reinstall Correctly

Install appropriate insulation for your property type

Pros: Regain energy efficiency
Cons: Additional cost £1,500-£3,000

Alternative Insulation

Internal wall insulation or other methods

Pros: No cavity issues
Cons: Higher cost, reduces room size

Get Cavity Wall Extraction Quotes

Connect with specialists who use proper extraction techniques, provide comprehensive surveys, and guarantee results. Get multiple quotes and understand all your options before proceeding.

Request Free Assessment