Client extranet for construction progress tracking in London: cost (2026)

The verdict in three sentences

For a main contractor in London, a client progress-tracking extranet changes the relationship with developers and employers: fewer justification meetings, faster-approved payment applications, better-documented snagging disputes. As a 2026 order of magnitude, the project costs 50,000 to 90,000 GBP depending on modules, with an offline app essential for site managers working in basements and dead zones. Allow 4 months to build, with ROI driven first by faster cash collection.

What the client wants to see, and what the site must capture

The managing director of a contractor running 8 to 12 projects at once (residential blocks in Hackney, warehouses near Park Royal, school refurbishments) gets weekly calls from clients asking about progress. Information flows through WhatsApp photos with no date or location, and monthly valuations go out as emailed PDFs, which delays certification.

The extranet serves both sides. The client sees a dashboard per project: progress by package, programme versus actual, a gallery of dated and geotagged photos, payment applications to approve, open and closed snags, signed handover certificates. The site manager captures everything in a mobile app that works offline and syncs as soon as signal returns.

The technical choices that move the price

Three factors explain the gap between 50,000 and 90,000 GBP. First, offline mode: an app that stores photos and forms locally and resolves sync conflicts needs roughly 30 % more mobile development. Second, integrations: connecting to the contractor's estimating or accounting system (Sage, Xero, COINS) adds 6,000 to 14,000 GBP. Third, certified e-signature on certificates, often requested by institutional clients.

UK public-sector clients increasingly ask for Cyber Essentials Plus, so it is worth budgeting from the start.

A 4-month plan

Month 1: workshops with project managers and two pilot clients, portal and app wireframes. Months 2 and 3: build of the portal, offline app and valuations. Month 4: pilot on 2 sites, fixes, site manager training, rollout across the portfolio. Ongoing evolution then runs at about 1,000 to 2,000 GBP a month.

Mini case study

James, managing director of a London main contractor, bills an average of 1.2 million GBP of valuations a month. Today each one takes 25 days to be certified and paid. With the extranet and photo evidence, that drops to 12 days. With working capital funded by an overdraft at 9 % a year, gaining 13 days on 1.2 million GBP saves about 3,850 GBP of interest a month, or 46,000 GBP a year. For a 70,000 GBP extranet, payback is about 18 months on that line alone, before counting meetings and disputes avoided.

FAQ

Does the app really work without signal on site?

Yes, forms, photos and snags are stored on the phone and uploaded once signal returns. A mid-range Android or iPhone from about 250 GBP is enough.

Do clients need to install anything?

No, they use the portal in a browser with a login per project. Read-only access can also be granted to the architect, QS or funder.

Can we start with a smaller budget?

A first release at 32,000 to 38,000 GBP (portal, photos, snagging) is possible, with valuations and accounting integration added in a second phase.

Where is the data hosted?

On a secure UK or EU cloud with daily backups, for about 100 to 400 GBP a month depending on photo volume, in line with UK GDPR.

Let's scope your project. Tell us your number of live projects, typical clients and current tools: we will price an extranet between 50,000 and 90,000 GBP, deliverable in 4 months. Detailed quote within 48 h. WhatsApp +221 77 596 93 33.