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Got more questions about damp & Cavity Wall Tie Failure? Describe the bit you're unsure about — the AI explains options, sequencing and what to ask the damp proofer.
Survey cavity wall ties.
Borescope inspection of wall ties — corrosion checked, replacement quoted by linear metre.
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Costs, timelines, pitfalls and the right questions to ask before any damp proofer starts on damp & Cavity Wall Tie Failure.
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Bulging not addressed
Severely bulging walls need structural intervention beyond ties. Ties stabilise but don't undo bulge.
Mortar colour mismatch
New pointing visible against old. Quality contractor colour-matches lime.
Insufficient tie density
Need typical 5 ties per m². Cheap installs use fewer.
Galvanised ties (older repair)
Older retrofits used galvanised ties — corrode again. Modern stainless steel necessary.
Costs & timeline
Know what it costs. Know when it ends.
Indicative UK ranges and what affects price.
Cost range
By job type
Inc. VAT · 2026
Source: NMT quotes
Source: NMT quotes
Cavity wall tie surveyIncluding endoscopy
£200–£500
Helical tie replacement (each)Per tie installed
£25–£60
Standard 4-bed install (300 ties)Typical project
£2.5k–£6.5k
Repointing per m²Where new ties installed
£30–£80/m²
Bulging wall structural fixIf major structural movement
£3.5k–£15k
Insurance-backed guarantee20–30 year cover
£200–£500
!
Quote spread is typically ± 18% — always get 3 quotes.
At a glance
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Damp Proofer explained
Cavity wall ties (steel rods linking inner and outer leaves) corrode over time. Failure causes bulging external walls and damp ingress through cracked mortar. Expect to pay £1,500–£6,500 for UK cavity wall tie retrofit.
What Does the Work Involve?
Endoscope inspection identifies corroded ties. Existing ties remain (would be impossible to remove without major work). New helical stainless steel ties inserted into pre-drilled holes through the outer brick into the inner masonry. Mortar joints re-pointed. Cosmetic colour-matching of new mortar.
Typical Costs
| Item | Low (£) | High (£) | Notes |
|---|---|---|---|
| Cavity wall tie survey | 200 | 500 | Including endoscopy |
| Helical tie replacement (each) | 25 | 60 | Per tie installed |
| Standard 4-bed install (300 ties) | 2,500 | 6,500 | Typical project |
| Repointing per m² | 30 | 80 | Where new ties installed |
| Bulging wall structural fix | 3,500 | 15,000 | If major structural movement |
| Insurance-backed guarantee | 200 | 500 | 20–30 year cover |
How Long Does It Take?
Survey: 1–2 hours. Tie replacement (typical house): 1–3 days. Scaffold time: 1 week.
DIY or Professional?
Professional. Specialist equipment for endoscopy and helical tie insertion. Working at height for scaffold work.
Choosing the Right Tradesperson
PCA structural waterproofing member or specialist contractor (Helibar, Twistfix, CET). Insurance-backed guarantee mandatory. 20–30 year warranty.
UK Regulations
Building Regs Part A (structure) if structural movement involved. PCA Code of Practice. Listed buildings need consent.
Common Problems
- Bulging not addressed: Severely bulging walls need structural intervention beyond ties. Ties stabilise but don't undo bulge.
- Mortar colour mismatch: New pointing visible against old. Quality contractor colour-matches lime.
- Insufficient tie density: Need typical 5 ties per m². Cheap installs use fewer.
- Galvanised ties (older repair): Older retrofits used galvanised ties — corrode again. Modern stainless steel necessary.
Frequently Asked Questions
How do I know my wall ties have failed?
Horizontal mortar cracks at regular intervals (where ties sit). Bulging external walls. Damp ingress through cracked mortar.
When were wall ties used?
Cavity walls from 1920s onwards used iron or galvanised steel ties. Pre-1970 ties most likely to have failed by now.
Helical ties — how do they work?
Helical (twisted) stainless steel rods drilled into both leaves. The helical shape grips mortar. No mechanical fixing needed — friction holds.
How many new ties do I need?
BS 5628 recommends 5 ties per m². Most houses need 200–400 ties retrofitted.
Will retrofit ties last as long as original?
Modern stainless steel ties last indefinitely. 25-year warranties typical, real-world life 60–100+ years.
Mortar cracking and damp — wall ties or different problem?
Get a survey. Endoscopy through small drilled holes confirms tie condition. Other causes possible (subsidence, weathering) but ties are common.
This guide was written with AI assistance and is intended for general information only. Prices are estimates based on UK averages and may vary by region. Always get at least three quotes and consult a qualified professional before starting any work.
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