The verdict in three sentences
The headline price of a maintenance contract means nothing until you have read the SLA, the included hours and the reversibility clause. In 2026, a credible retainer for a B2B brochure site runs between 100 and 400 EUR/month, but the real cost driver is the guaranteed response time. Negotiate scope and exit first, price second.
The clauses that structure the contract
A serious maintenance contract covers four families: availability (SLA), security, evolutions and governance. Every line below must appear in black and white in your 2026 quote; a single missing one is a negotiation signal.
| Clause | 2026 range (order of magnitude) | Watch out for |
|---|---|---|
| Monthly retainer (brochure site) | 100-400 EUR/month | What is included vs billed extra |
| Guaranteed uptime (SLA) | 99.5% to 99.9% | Penalties if missed? |
| Critical response time | 4h to 24h | Business hours or 24/7 |
| Included evolution hours | 1 to 4 h/month | Rollover of unused hours |
| Backups | Daily, 30-day retention | Real restore test |
| Security updates | Within 48h of patch | CMS + plugins covered? |
| Reversibility | Code + DB within 15 days | Format and exit cost |
SLA: the detail that moves the bill
A 99.9% uptime allows about 8.7 hours of downtime per year; at 99.5% you climb to 43.8 hours. For a site that generates B2B leads, that gap adds up quickly. Require the SLA to state the measurement scope (excluding planned maintenance), the verification method (third-party monitoring) and above all the penalties.
| SLA tier | Max downtime/year | Response time | Indicative surcharge |
|---|---|---|---|
| Standard 99.5% | 43.8 h | 24 business h | included |
| Business 99.9% | 8.7 h | 4-8 business h | +30 to +60 EUR/month |
| Critical 99.95% | 4.4 h | 2h 24/7 | +150 EUR/month |
Mini case study
Claire, CFO of an industrial SME in Lyon, receives two offers for her brochure site. Offer A shows 150 EUR/month with no included evolution hours; offer B, 320 EUR/month with 3h/month included and a 99.9% SLA. Over a year, offer A costs 1,800 EUR but its 36 evolution hours billed at 90 EUR/h add 3,240 EUR, for 5,040 EUR. Offer B totals 3,840 EUR all-in. By negotiating hour rollover and a free reversibility clause, Claire saves 1,200 EUR/year and secures her exit.
FAQ
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Is maintenance mandatory after delivery?
Nothing contractually forces it, but a site without security updates becomes vulnerable within months. Budget at least an 80-120 EUR/month security retainer for a brochure site.
What does a basic retainer actually cover?
Usually: supervised hosting, backups, CMS updates and minor fixes. Functional evolutions (new page, new form) are almost always outside the retainer, at 60 to 120 EUR/h in 2026.
How do I avoid being locked in with my agency?
Require a reversibility clause: handover of source code, credentials and database within 15 days, in a usable format, with no hidden fees. It is the most frequently forgotten point.
Is a 99.9% SLA really worth the surcharge?
Yes if your site is an active sales channel. For a low-traffic institutional site, a 99.5% SLA is often enough and saves 300 to 700 EUR/year.
Can I terminate easily?
Negotiate a 30 to 60-day notice period and refuse 24-month commitments without an exit clause. A 12-month term with reversibility is a good 2026 standard.
Let's scope your project. Tell us about your current site, your traffic and the SLA level you need: we will frame a clear maintenance retainer, reversibility included. 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.
