Construction ERP for a Mid-Sized German Bau Contractor

Client Context

Bau Nord is a Hamburg-based general contractor with ~180 staff running 14–18 active construction sites across Northern Germany at any time, mostly mid-rise residential and light industrial projects in the €2M–€18M range. Site managers tracked material delivery, labor hours and subcontractor approvals in spreadsheets stored on a shared drive. Two prior ERP attempts (one large German vendor, one industry-specific package) had been cancelled in pilot because the workflow assumptions did not match how the site managers actually worked.

Signals Before We Started

• Average 5.2 working days from subcontractor invoice receipt to approval

• 6–9% project cost overruns, mostly detected at month-end

• Material orders duplicated across sites — ~€140K of unnecessary stock at peak

• Site managers spent ~6h/week on reporting (≈14% of their time)

• Two prior ERP rollouts cancelled in pilot — strong organizational scepticism

1. Phase 1 — Discovery on site

   Week 1–3
   Goals

   • ·Shadow three site managers and one controller through a full week
   • ·Inventory every spreadsheet template and approval chain in use
   • ·Agree the success KPI (approval lead time + cost-overrun visibility)

   Outcomes

   • ✓Documented 11 approval chains and 14 spreadsheet templates
   • ✓Identified two non-negotiables: must work offline on a phone; must export to DATEV in their existing chart of accounts
   • ✓Pilot site selected (one mid-rise residential project starting week 6)

2. Phase 2 — Core domain & approvals

   Week 4–10
   Goals

   • ·Project, Site, Subcontractor, Material, Labor, Approval domain in code
   • ·Mobile-first material delivery + labor capture screens
   • ·Multi-level approval workflow with delegation

   Outcomes

   • ✓Pilot site live week 10 with material + labor capture only
   • ✓Average approval time dropped to 2.4 days on pilot site
   • ✓First production incident: offline sync conflict — resolved with last-write-wins + audit

3. Phase 3 — Procurement & controlling

   Week 9–18
   Goals

   • ·Material ordering with cross-site visibility
   • ·Project cost rollup with budget vs actual
   • ·Executive dashboard for managing director

   Outcomes

   • ✓Detected €140K of duplicated material orders in the first month
   • ✓Cost overrun visibility shifted from month-end to weekly
   • ✓Executive dashboard adopted by the MD as the standing Friday review artefact

4. Phase 4 — DATEV & finance

   Week 15–22
   Goals

   • ·DATEV-compatible accounting export
   • ·Parallel run with existing accounting for 6 weeks
   • ·Reconcile and certify export with the tax advisor

   Outcomes

   • ✓DATEV export reconciled to the cent over 6 weeks
   • ✓Controller team weekend overtime eliminated by week 22

5. Phase 5 — Rollout

   Week 18–32
   Goals

   • ·Roll out site by site (2 sites per fortnight)
   • ·Decommission old spreadsheets
   • ·Train backup site managers

   Outcomes

   • ✓All 18 active sites migrated by week 30
   • ✓Approval lead time stabilized at 1.4 working days across the company
   • ✓Project cost overruns dropped to 2–4% in the first two completed projects post-rollout