The verdict in three sentences
An engineering firm that still exchanges drawings, calculation notes and minutes by email wastes time and takes a real risk on versions and confidentiality. A custom client extranet costs GBP 17,000 to 43,000, with UK hosting at GBP 85 to 260 a month, over 3 to 4 months. The measured gain is around 5 hours per week per project manager, which pays back the investment in under a year for a 90-person firm.
What the extranet must do for a design office
An engineering firm needs more than file sharing: a client must know which revision of a drawing is approved, who issued it and when. Here are the modules to price.
| Module | Concrete use | Indicative 2026 cost (ex VAT) |
|---|---|---|
| Project space per client with role-based access | Clients see their jobs, not anyone else's | GBP 3,500 to 7,000 |
| Document sharing with revisions (P01, P02, C01) | End of « drawing_v3_final_FINAL.pdf » | GBP 4,300 to 10,000 |
| Review and approval workflow | Record of who approved which revision | GBP 2,500 to 6,000 |
| Two-factor authentication and access log | Common requirement from industrial and public clients | GBP 1,700 to 3,500 |
| Progress dashboard (milestones, snags) | Replaces weekly status emails | GBP 2,500 to 7,000 |
| Notifications and weekly digest | Clients stay informed without chasing | GBP 1,300 to 2,500 |
| Integration with internal tools (ERP, EDMS) | Avoids double entry | GBP 2,500 to 8,500 |
Custom build, SharePoint or a CDE platform: the comparison
| Option | Upfront cost (ex VAT) | Recurring cost | Strengths | Limits |
|---|---|---|---|---|
| SharePoint / Teams guests | GBP 1,700 to 5,000 setup | Existing licences | Quick to open | Clunky for clients, revisions hard to read |
| Off-the-shelf construction CDE | GBP 2,500 to 7,000 | GBP 13 to 35 per user per month | Ready-made industry features | Cost climbs with invited client users |
| Custom extranet | GBP 17,000 to 43,000 | GBP 85 to 260/month hosting + GBP 260 to 700 maintenance | Firm branding, tailored approval workflow | Higher initial investment |
| Hosting with Cyber Essentials Plus / ISO 27001 supplier | +20 to 40 % on hosting | GBP 210 to 500 per month | Required by some public sector clients | Rarely needed for private engineering work |
A custom build makes sense once client accounts pass about a hundred: at GBP 21 per user per month, 120 accounts cost GBP 30,000 a year in licences.
Security: what to require in the specification
UK hosting with an ISO 27001 certified provider, encryption of files at rest, mandatory two-factor authentication for external accounts, access logs kept for 12 months, daily backups with 30-day retention and a tested restore. Also budget a penetration test before go-live, GBP 2,500 to 5,000, and documented UK GDPR compliance (records, retention periods).
Mini case study
Sarah, operations director of a 90-person engineering firm in London, oversees 12 project managers. Each spends about 5 hours a week finding, renaming and resending documents. Over 45 working weeks at a loaded cost of GBP 48 an hour, that is 12 × 5 × 45 × 48 = GBP 129,600 a year. A GBP 32,000 extranet plus GBP 4,100 a year in hosting and maintenance pays back in under 4 months, even if only half of the lost time is recovered.
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FAQ
How much does a client extranet for an engineering firm cost?
In 2026, expect GBP 17,000 for a simple document extranet and up to GBP 43,000 with approval workflow, dashboards and ERP integration. UK hosting adds GBP 85 to 260 a month.
What timeline should we plan?
A typical project runs 3 to 4 months: 3 weeks of scoping, 8 to 10 weeks of development, then 2 to 3 weeks of acceptance testing with two pilot clients.
Does two-factor authentication annoy clients?
With an authenticator app or an email code, login takes about 10 seconds longer. It sharply reduces the risk of compromised accounts, the leading cause of document leaks.
Can existing documents be migrated?
Yes, migration from a file server or SharePoint is priced separately, usually GBP 1,700 to 4,300 depending on volume and folder clean-up.
Who owns the code?
The contract should assign the rights and hand over the source code. You remain free to change maintenance provider.
Let's scope your project. Tell us your number of active clients, current tools and security requirements to receive a quote between GBP 17,000 and 43,000 with a 3 to 4 month plan. 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.
