How to Price Cavity Wall Tie Replacement: Labour, Materials and Margin Guide

Quick Answer: Cavity wall tie replacement in the UK prices at £12-£25 per tie installed, with a typical semi-detached elevation needing 200-400 ties and costing £2,500-£6,000, and a full house £5,000-£12,000. Pricing is driven by tie density (BS EN 845-1 / approved-document spacing of roughly 2.5 ties/m², ~900mm horizontal × 450mm vertical), access (scaffold vs ladder), and whether failed ties must also be isolated. A structural survey with a borescope (£250-£500) is essential before quoting — you cannot price ties you cannot count.

Summary

Wall tie failure is one of the most common structural defects in 20th-century UK cavity-walled housing. The original galvanised mild-steel "fishtail" and "butterfly" ties used from roughly the 1920s to the 1980s have a finite life — the zinc coating eventually depletes and the steel corrodes, expands ("rust jacking"), and cracks the mortar beds. Left untreated, the outer leaf loses its structural connection to the inner leaf and can bulge or, in severe cases, become unstable.

Pricing tie replacement well requires understanding that the visible symptom (horizontal cracking at regular ~450mm vertical intervals, bulging brickwork) is the late stage. The job is priced per tie installed, so the two questions that set the price are: how many ties does the wall need (density × area), and how do you reach them (access). A retro-tie installation is fast per tie once set up, so mobilisation, scaffold, and survey dominate small jobs.

This guide separates the survey, the tie count, the access, the installation method (mechanical expansion vs resin-bonded), the isolation of failed ties, and the making good. It covers when bulging brickwork must be rebuilt rather than re-tied, and the guarantee angle. For related masonry work see lintel replacement pricing guide, external render pricing guide and damp proofing pricing guide.

Key Facts

Tie and material costs

Labour, access and ancillary costs

Regulatory and standards

Quick Reference Table

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Scope Approx Ties Access Typical Cost
Single elevation (small) 100-200 Ladder/tower £1,500-£3,000
Semi-detached (one+ elevation) 200-400 Scaffold £2,500-£6,000
Full house re-tie 400-800 Scaffold £5,000-£12,000
Re-tie + crack stitching varies Scaffold +£25-£45/m cracks
Re-tie + bulge rebuild varies Scaffold +£80-£200/m² rebuild

Tie density is roughly 2.5 ties/m² (≈900mm horizontal × 450mm vertical), increased at reveals, jambs, and within 225mm of openings.

Detailed Guidance

Survey first — count and confirm

Never quote tie replacement without a survey. The surveyor uses a metal detector to locate existing ties and a borescope (inserted through a small drilled hole) to inspect their condition inside the cavity. This confirms: that the ties have actually failed (corroded, debonded, or absent); the cavity width and construction; whether there is cavity-fill insulation in the way; and the wall area to be re-tied. From the area, the tie count follows at the required density. Budget £250-£500 for the survey — it is the basis of an accurate quote and protects against over- or under-tieing.

Tie density and pattern

Remedial ties are installed at a density matching current standards — broadly 2.5 ties per square metre, set out at roughly 900mm horizontal centres and 450mm vertical centres (every sixth brick course), with additional ties at openings, reveals, movement joints, and within 225mm of jambs. The pattern is set out on the wall before drilling. Getting the density right is both structural and commercial — under-tieing fails the wall, over-tieing inflates the customer's bill. Quote the count from the surveyed area, not a guess.

Installation method

Two main retro-fit systems:

  1. Mechanical expansion ties — a stainless steel tie inserted into a drilled hole and expanded to grip both leaves. Fast, clean, no curing time, suits most brick and dense block. £12-£20/tie installed.
  2. Resin-bonded ties — a stainless tie set in injected resin, gripping the full length of the hole. Better in soft or perforated brick, weak mortar, and where a stronger fix is needed. Slightly slower (cure time) and dearer. £15-£25/tie installed.

Helical/screw-in ties are a third option, driven into pre-drilled or pilot holes. All ties must be austenitic stainless steel (grade 304 minimum, 316 for exposed/coastal) — never galvanised, which is what failed in the first place.

Isolating the failed ties

Existing corroded ties continue to expand and crack the mortar even after new ties are fitted. Best practice is to isolate them — cutting or capping the embedded ties so they can no longer transmit expansion forces to the brickwork. This is an extra £3-£8 per failed tie and is genuinely important: re-tieing without isolating the corroding originals leaves the cracking mechanism live. Reputable specifications include isolation; budget firms omit it. Quote it explicitly.

When re-tieing isn't enough — bulging and rebuild

If the outer leaf has already bulged or deflected significantly (typically more than the wall thickness divided by certain limits, per the engineer), re-tieing alone won't restore it — the bulged section must be taken down and rebuilt. This is a major step up in cost (£80-£200/m² to rebuild) and needs propping and an engineer's input. The survey must distinguish "ties failed, wall still plane" (re-tie) from "wall bulged" (rebuild). Misjudging this is a serious error.

Cavity-fill insulation complication

Where the cavity has been filled (blown mineral fibre, beads, or foam), retro-tieing is more difficult — the drill and tie must pass through the fill, and resin systems behave differently. Borescope inspection through fill is harder. Allow extra time and survey carefully; some fills (particularly UF foam) signal the wall is older and the ties likely original mild steel.

Making good and guarantees

After installation the drill holes are plugged with colour-matched mortar (included in the tie rate). Repointing of the affected courses (£15-£35/m²) and any crack stitching (helical bars bonded into raked-out bed joints, £25-£45/m) are separate. For resale and mortgage purposes a PCA-backed structural guarantee (commonly 10-30 years) is usually wanted — price it as a line item.

Frequently Asked Questions

How do I know if wall ties have failed?

The classic sign is regular horizontal cracking in the mortar beds at roughly 450mm vertical intervals (the tie spacing), often with the cracks stepping along the wall. Other signs: bulging or bowing of the outer leaf, lifting of the brickwork at the top of the wall ("rising" of the outer leaf relative to the inner because corroding ties expand), and cracking around openings. Confirm with a borescope survey — surface cracking can have other causes.

Why are wall ties replaced rather than just repointing the cracks?

The cracking is a symptom of the structural connection between the two leaves failing. Repointing hides it temporarily but the outer leaf is still progressively losing its tie to the inner leaf and will continue to move and crack — and eventually bulge. Re-tieing restores the structural connection; repointing alone is cosmetic and will fail again.

Do new ties need to be stainless steel?

Yes — always austenitic stainless steel (grade 304 minimum, grade 316 for coastal or severely exposed walls). The original ties failed because galvanised mild steel corrodes once the zinc depletes. Installing anything other than stainless simply rebuilds the same time-bomb. Reputable specifications and guarantees require stainless.

Will I need scaffolding?

For anything above the ground floor or covering a full elevation, yes — scaffold (or at least a tower) is needed for safe, productive working and accounts for a significant share of the cost (£600-£3,000 depending on extent). Small, low-level areas can sometimes be done from ladders or a tower, but the access cost is one of the main reasons small tie jobs have a high per-tie effective rate.

Regulations & Standards