Home / Case Studies / £8M Unitised Curtain Wall · Central London
Featured · Live CASE-2025-007 Façade · Central London · 24-month programme

£8M unitised curtain wall.
£1.01M total value protected.

Sector
Façade
Package
Unitised curtain wall
Storeys
12 above ground
Contract
JCT D&B with amendments
Engagement
Retained · Full lifecycle
Variations won
£380K
Recovered & substantiated. 6 variations from £28K to £120K.
EOT granted
47 days
Across 8 separate Relevant Events. 12 EWNs served on time.
LADs avoided
£210K
Programme exposure neutralised by EOT entitlement.
Total protected
£1.01M
Variations + LADs avoided + final account uplift.

An £8M package in a contract written to fail.

A specialist curtain-wall subcontractor was about to sign a JCT Design & Build subcontract for a 12-storey commercial tower in Central London. £8M contract value over a 24-month programme.

The tender documents had been issued with seven weeks to bid. The back-to-back terms were aggressive. The programme baseline assumed structure handover dates the structural contractor had already publicly missed on a separate package.

Ashton Blake was brought in at bid stage — three weeks before the contract was due to be signed.

The risk register, on day one.

Before the contract was signed, we performed a structured red-flag review of the tender pack. Fourteen clauses were flagged as either commercially toxic or unenforceable in their drafted form.

RISK · 01Back-to-back EOT entitlement stripped — subcontractor would carry all programme risk for events caused by the main contractor.
RISK · 02LADs at £30K/week with no carve-out for MC-caused delay. Modelled exposure: £400K+ over likely slippage window.
RISK · 03Variations only payable if instructed in writing in advance — verbal/site instructions excluded.
RISK · 04Payment notice regime non-compliant with HGCRA — pay-less notice window unrealistically short.

Embedded from day −21 to retention release.

Four phases. Twenty-four months. Daily reporting, weekly progress meetings, monthly board dashboards. Records-first methodology applied throughout.

Phase 01 · Bid stage
01
−21 days to contract

Contract review & risk negotiation.

Structured red-flag review of tender pack. 14 risk clauses identified across commercial, programme, and contractual streams. Drafted a counter-proposal memorandum with proposed amendments and supporting rationale.

Negotiated 9 of 14 flagged clauses to acceptable form
Carved out LAD application for MC-caused delay events
Restored verbal-instruction variation route with confirmation procedure
Rewrote payment notice regime to HGCRA-compliant timings
Outcome
9 / 14 fixed
Risk reduction
£420K est.
Phase 02 · Pre-construction
02
−14 days to mobilisation

Baseline lock & records system deployment.

Programme baseline formally agreed and signed off by both parties. Contemporaneous record system deployed — daily site report template, photographic protocol, document-control flow, EWN tracker. Site team trained on capture discipline before boots hit site.

Baseline programme signed off jointly — locked reference point
Daily site report by 18:00 — workflow established before mobilisation
Lift plan prepared and approved by Appointed Person (LOLER)
CDM 2015 duty-holder responsibilities mapped and acknowledged
Records system
Live · Day 1
Lift plan
AP-approved
Phase 03 · Installation
03
Months 1 — 18

Notice discipline & variation capture.

12 Early Warning Notices served within contract timescale — each tied to a Relevant Event with substantiating records. 8 EOTs granted, totalling 47 days of additional programme. 6 variations captured, valued at £380K — all priced from contemporaneous records and substantiated in advance of monthly application.

EWN-001 to EWN-012 served — every notice within contract window
Daily photographic record tagged to plan grid for variation evidence
Multi-trade clash log live — 3 structure–façade interface issues escalated & resolved
Monthly commercial dashboard to client board · RAG-rated · partner-signed
EWNs served
12 of 12 on time
EOT granted
47 days
Variations
£380K
Phase 04 · Completion
04
Months 19 — 24

Final account & retention release.

Final account submitted at £9.2M — supported by full record substantiation. Scott Schedule prepared in parallel as adjudication-ready fallback. Snagging programme reduced defect list by 60% before practical completion. Retention released on schedule, no withholdings.

Final account £9.2M submitted with full evidence pack
Scott Schedule pre-prepared — never needed, but ready to deploy
60% snagging closeout before PC — minimal punch-list at handover
Retention released to subcontractor on contractual date
Final account
£9.2M agreed
Retention
Released on time

The Scott Schedule that never had to be filed.

Of the six captured variations, four required formal Scott Schedule preparation. Without contemporaneous records and prior substantiation, the main contractor's typical recovery rate is 30–35%. With Ashton Blake's records, this case settled at 95%.

Item
Description
SC claim
MC response
Evidence (AB)
AB assessment
V-001
Additional bracketry — Zone B intermediate fix
£45,000
Rejected · scope
DRG rev C → rev D · RFI-027
£42,500
V-002
Design change · Zone A glazing reconfiguration
£120,000
Partial · £60K
RFI-034 · AI-012 · daily logs
£115,000
V-003
Access delay costs · scaffold reposition
£28,000
Rejected · no notice
EWN-003 · daily logs · timesheets
£28,000
V-004
Additional lifting operations · revised programme
£35,000
Partial · £15K
Lift plans rev A · timesheets · AP log
£32,000
Total · 4 variations
£228,000
£75,000
£217,500
Without contemporaneous records
33%
Industry-typical recovery rate when records are reconstructed post-event.
With Ashton Blake records
95%
Settled at near-full claim value. Two variations agreed without dispute hearing.
Net difference · this dispute alone
£142,500
Value that would have been left on the table without proactive evidence discipline.

£1.01M of value protected, per project.

Line item
Detail
Value
Contract value (original)
JCT D&B
£8,000,000
Variations recovered & substantiated
6 of 6 valued
£380,000
LADs avoided (47-day EOT)
8 Relevant Events
£210,000
Bid-stage contractual risk reduction
9 of 14 clauses renegotiated
£420,000
Total value protected
All sources
£1,010,000
Ashton Blake fees · 24-month engagement
~£120,000 · for £1.01M protected
8.4×

What we ran on this project.

Same outcome · your next project · free 15-minute review

Bring us in before the contract is signed.

The £420K of bid-stage risk reduction on this project was only possible because we arrived three weeks before the signature. Every week earlier we're brought in compounds the value protected.

Response timeSame working day
Partner levelRICS / MCIOB / APM
ConfidentialityNDA on request
CoverageUK · Europe · MENA · CIS