The verdict in three sentences
For a structural engineering firm of 15 to 40 engineers in London, a custom client portal costs between 25,000 and 60,000 EUR in 2026 (roughly 21,000 to 51,000 GBP), depending on the depth of the approval workflow and storage volume. The payback comes mostly from time lost hunting for the right drawing revision and from revision errors that trigger rework on site. Before signing, decide whether you need a shared document store or a real review and approval workflow with an auditable trail.
What the portal must do, and what it costs
A typical concrete and steel structural practice needs five building blocks: drawing upload by package and revision, approval by the architect or checking engineer, markups on PDF or DWG, notifications, and handover archiving (O&M and as-built files). Each block has a fairly predictable development cost.
| Module | Function | UK/EU market estimate 2026 (EUR) |
|---|---|---|
| Project spaces and permissions | One space per job, roles for architect, client, engineer, checker | 4,000 - 8,000 |
| Drawing upload and versioning | Revisions P1, P2, C1, history, version comparison | 6,000 - 14,000 |
| Approval workflow | Status A / B / C, deadlines, automatic reminders | 5,000 - 12,000 |
| Viewer and markups | PDF and DWG viewing in the browser, comment bubbles | 4,000 - 10,000 |
| Notifications and dashboard | Emails, overdue alerts, overview per project | 2,000 - 6,000 |
| Handover archive and export | As-built package in one click | 2,000 - 5,000 |
| SSO and security | Strong authentication, access log, UK or EU hosting | 2,000 - 5,000 |
A reduced scope (spaces, upload, simple approval) stays around 25,000 EUR. A full portal with a native DWG viewer and integration with your analysis software or ERP moves towards 60,000 EUR. The realistic timeline is 3 to 5 months, including one month of scoping and acceptance testing with two or three partner architects.
Storage, hosting and maintenance: the recurring cost
Drawings are heavy. A mid-sized engineering firm accumulates 2 to 5 TB of files over five years, IFC models included. That volume drives hosting.
| Recurring item | Monthly range 2026 (EUR) | Comment |
|---|---|---|
| Object storage 2 TB | 40 - 90 | Price per TB falling, replication included |
| Object storage 5 TB | 100 - 220 | Plan for it once BIM models come in |
| Application server and database | 80 - 250 | Depends on concurrent users |
| Off-site backups | 30 - 80 | 30 to 90 day retention |
| Corrective and evolutive maintenance | 400 - 1,200 | Fixes, security updates, small changes |
| External user support | 0 - 300 | If architects call you directly |
Budget 550 to 2,000 EUR per month all in. Compare that with Aconex or Viewpoint: both are excellent on large multi-party projects, but pricing is usually per project or per seat, and an engineering firm active on 20 jobs can easily pass 800 to 1,500 EUR per month, with external parties often needing their own licences or invitations.
Custom build or Aconex / Viewpoint?
| Criterion | Aconex / Viewpoint | Custom portal |
|---|---|---|
| Time to start | Days | 3 to 5 months |
| Upfront cost | Low | 25,000 - 60,000 EUR |
| Recurring cost (20 jobs) | 800 - 1,500 EUR / month (estimate) | 550 - 2,000 EUR / month |
| Fit with your revision naming | You adapt to the tool | Built around your process |
| Data ownership | Vendor platform | Your infrastructure |
| Commercial differentiation | None | Branded portal for clients |
If the main contractor already imposes Aconex, you will use it anyway. A custom portal makes sense when you want control of your data, a perfect fit with your drawing register and a branded tool that wins developer clients. If you only need to share PDFs, a standard document store is enough, and we will tell you so.
For a tighter scope, Kolonell builds custom applications on its 2026 grid: medium complexity 4,000,000 to 7,000,000 FCFA (6,100 to 10,670 EUR), high complexity 7,000,000 to 15,000,000 FCFA and above (10,670 to 22,870 EUR and above), maintenance 75,000 to 120,000 FCFA per month (110 to 180 EUR).
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Mini case study
Claire, managing director of a 22-person structural engineering firm in London (Farringdon), runs 35 projects a year. Her engineers each spend about 4 hours a week finding, resending or checking drawing revisions: 22 x 4 x 45 weeks = 3,960 hours a year. A portal that halves this time frees 1,980 hours. At a loaded hourly cost of 60 EUR, that is 118,800 EUR a year. For a 45,000 EUR portal and 1,200 EUR a month of running costs (14,400 EUR a year), payback comes in under 6 months, before counting avoided site rework.
FAQ
How much does a client portal for a structural engineering firm cost in 2026?
Expect 25,000 to 60,000 EUR of development, plus 550 to 2,000 EUR a month to run it. The spread depends mainly on the approval workflow and the DWG viewer.
How long until the portal is live?
Usually 3 to 5 months. A first working release (upload, revisions, simple approval) can ship in 8 to 10 weeks to pilot with two partner architects.
Should we plan for 2 TB or 5 TB of storage?
A firm handling only PDFs fits in 2 TB for several years. Once IFC models and heavy calculation packages arrive, plan for 5 TB and about 100 to 220 EUR a month of storage.
Does the approval trail hold up in a dispute?
The portal timestamps every upload, approval and rejection with the user identity. That log serves as evidence in a revision dispute, provided you keep it for at least 12 years, the limitation period for contracts executed as deeds in England.
Can the portal connect to our existing software?
Yes, through APIs or file exports: project ERP, analysis software, email. Budget 3,000 to 8,000 EUR per connector depending on the vendor API quality.
Let's scope your project. Send us your drawing register and number of live projects: we will price the scope, give an indicative budget and a timeline per release. 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.
