How much does construction project software cost in London in 2026?

The verdict in three sentences

For a construction director in London, an industry SaaS at 40-100 EUR/user/month covers 80 % of site-tracking needs without heavy investment. As soon as your progress claims, subcontractors and field app must match your own processes, a custom build at 35,000-75,000 EUR pays back within 12 to 18 months. The decision comes down to two numbers: -3 days per progress claim and -10 % of budget drift.

Industry SaaS vs custom: the real comparison

Specialist editors bill per user or per active site. A custom build is paid once, plus annual maintenance. 2026 orders of magnitude for a 15-40 person firm.

At 20 users, SaaS overtakes custom on cost between year 3 and 4. Below 10 users, SaaS is almost always the right call.

What makes a site budget drift — and what software recovers

Drift comes from an accumulation of tracking gaps, not a single line item. A tool that centralises quotes, variations, claims and subcontracting closes those gaps.

On an 800,000 EUR project, recovering 6 margin points is 48,000 EUR — the full cost of a custom build.

How to decide in practice

The decision is not about the sticker price but about three concrete questions. First, your volume: below 10 field users, SaaS almost always wins, because the subscription stays under the amortised cost of a build. Second, how specific your processes are: if your progress claims, variations and subcontracting chain follow rules editors do not model, every manual workaround cancels the SaaS gain. Third, your horizon: a custom build only pays back from 24-36 months, so it only makes sense if you are committed for the long run and code ownership has strategic value. A hybrid approach is often the most profitable in 2026: start on an industry SaaS to frame your needs for 12 to 18 months, then move to custom once your processes are stable and your pain points documented. This sequence avoids paying for a build frozen around still-fuzzy needs, while preparing a controlled migration. The typical tipping point sits around 15-20 active users, when the annual SaaS bill exceeds 18,000-24,000 EUR and functional limits become daily blockers.

Mini case study

Thomas runs a 28-person structural works firm, 6.2 M EUR revenue, 14 concurrent sites. He loses on average 4 days per progress claim consolidating time sheets and subcontractor slips, across 9 monthly claims. At a loaded cost of 380 EUR/day for his site manager, that is 4 × 9 × 380 = 13,680 EUR/month of unproductive time. A 58,000 EUR custom build that cuts this to 1 day saves ~10,260 EUR/month — payback in just under 6 months. Add the 6 recovered margin points on variations and the break-even drops below 4 months.

FAQ

What is the minimum budget to start without going custom? Budget 40-60 EUR/user/month for an industry SaaS covering site tracking, claims and a field app — 8,000-14,000 EUR/year for a team of 15.

How long to build a custom solution? Between 4 and 7 months for a sites + claims + field app + dashboard scope, with a usable V1 in 10-12 weeks.

Does the field app work offline? Yes: good 2026 solutions handle offline mode with deferred sync, essential on sites without coverage. Budget 6,000-12,000 EUR for this custom module.

Can the software connect to my accounting? Yes, via API or export. A Sage or Pennylane integration is 3,000-8,000 EUR custom and saves 15-20 hours of monthly re-entry.

What realistic gain on budget drift? 2026 feedback lands around -8 to -10 points of drift when variation and claim tracking is fully digitised end to end.

Let's scope your project. Tell us your site volume, number of field users and accounting tools, and we will frame SaaS vs custom with an indicative budget. Detailed quote within 48 h. WhatsApp +221 77 596 93 33.