The verdict in three sentences
A contractor in London running 8 to 20 sites in parallel loses on average 3 to 7% margin because materials and labour overruns only surface at final account. A custom tracking app at GBP 45,000 to 120,000 (mobile site diary, materials consumption, valuations, geotagged photos) flags those variances 3 to 6 weeks earlier. Against international SaaS at USD 40 to 80 per user per month, custom becomes cheaper over 3 years once you pass roughly 60 to 80 users, and it fits your own workflows exactly.
What the app must cover on site
A site manager must be able to log the day in 5 minutes from a phone, including in basements and new builds with poor signal. Everything else follows from that constraint.
| Function | Site use | Effect for the operations director | Indicative budget |
|---|---|---|---|
| Offline mobile site diary | Headcount, weather, tasks, incidents | Real progress per package, day by day | GBP 9,000 to 21,000 |
| Materials tracking (concrete, rebar, aggregates) | Delivery notes, consumption, stock | Planned vs consumed quantities | GBP 9,000 to 24,000 |
| Geotagged, timestamped photos | Evidence of progress and snags | Fewer disputes with the client | GBP 4,500 to 10,500 |
| Valuations and interim applications | Measurements approved on site | Monthly billing without delay | GBP 7,500 to 18,000 |
| Labour and subcontractor attendance | Daily sign-in | Real labour cost per site | GBP 6,000 to 15,000 |
| Multi-site dashboard | Consolidated view | Alerts from a 5% budget variance | GBP 7,500 to 18,000 |
| Payroll export for site labour | Weekly pay run | Fewer timesheet errors | GBP 3,000 to 7,500 |
2026 order of magnitude for a contractor of 40 to 150 staff.
Custom vs international SaaS
| Criterion | International SaaS | Custom app |
|---|---|---|
| Upfront cost | Low, set-up GBP 3,000 to 9,000 | GBP 45,000 to 120,000 |
| Recurring cost (40 users) | USD 40 to 80 × 40 × 12 = about GBP 15,000 to 30,000 a year | GBP 7,500 to 15,000 a year |
| Offline operation | Partial depending on vendor | Designed for it, deferred sync |
| Fit with your processes | Generic templates | Your packages, units and approval chain |
| Integration with your ERP or payroll | Paid connectors, limited | Built to your systems |
| Data ownership | Vendor platform | Yours |
| 3-year cumulative cost (40 users) | GBP 54,000 to 99,000 | GBP 67,500 to 165,000 |
Under 40 users a SaaS is usually cheaper; custom wins as user numbers grow, or when integration and specific workflows matter more than licence price.
Rollout in 4 to 6 months
The project starts with two weeks embedded on two pilot sites. Phase 1 (mobile diary, materials, photos) ships in 8 to 10 weeks and is tested on those sites. Phase 2 adds valuations, attendance, payroll export and the dashboard, then the tool is rolled out to all sites. Site manager training takes half a day, on their own phones.
Mini case study
James, operations director of a London contractor, runs 14 sites for GBP 32M in annual turnover. Materials overruns spotted too late cost him about 4% margin. He invests GBP 95,000 in a custom app, plus GBP 12,000 a year in maintenance.
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- Current overrun: 4% × GBP 32M = GBP 1,280,000.
- Prudent assumption: a quarter of variances avoided thanks to detection 4 weeks earlier, i.e. GBP 320,000 a year.
- Net gain after maintenance: GBP 308,000 a year.
- Payback: 95 / 308 = about 4 months.
FAQ
Does the app work without signal on site?
Yes, all entries are stored on the phone and synced as soon as 4G or wifi returns. Any recent Android or iPhone is enough.
How much does construction tracking software cost in London?
Between GBP 45,000 and 120,000 depending on modules, then GBP 7,500 to 15,000 a year for maintenance and hosting.
Can it feed our payroll and accounting?
Yes, attendance generates a weekly export to your payroll and cost data flows to your ERP. Connectors are scoped in the first workshop.
How long until we are operational?
Phase 1 goes live in 8 to 10 weeks on 2 pilot sites. Full rollout takes 4 to 6 months.
Do the photos hold up in a dispute?
They are timestamped, geotagged and locked after upload. They strongly support snag lists and interim valuations with the client.
Let's scope your project. Tell us your number of sites, field users and main overrun areas: we will price a scope between GBP 45,000 and 120,000, deliverable in 4 to 6 months. Detailed quote within 48 h. WhatsApp +221 77 596 93 33.
Mohamed Bah
Fondateur, Kolonell
Passionate about digital and entrepreneurship in Africa, Mohamed has been helping Sénégalese businesses with their digital transformation since 2020. Founder of Kolonell, he believes every SME deserves a professional and accessible online présence.
