The verdict in three sentences
A multilingual B2B site without a maintenance retainer degrades fast: security holes, stale content, out-of-sync languages. In London in 2026, a retainer runs between GBP 130 and 520/month by service tier, and each language adds 15 to 25 % to maintenance cost. A good contract clearly defines scope, SLA (uptime, response time) and enhancement volume.
The maintenance retainer tiers
Maintenance covers corrective, evolutive and preventive work. Here are the 2026 tiers and prices for a London B2B site.
| Tier | 2026 price | Included scope |
|---|---|---|
| Essential | GBP 130-220/mo | Updates, backups, security fixes |
| Business | GBP 220-350/mo | + monitoring, 2-4 h enhancements/mo |
| Premium | GBP 350-520/mo | + stronger SLA, 5-8 h enhancements/mo |
| Ad-hoc enhancement | GBP 300-560/day | Out of retainer, quoted |
| Extra language | GBP 1,300-4,000 | i18n setup + translation |
For an EN/FR/AR site, the Business tier (GBP 300/month) is often the right balance, with a separate budget for ad-hoc enhancements.
SLA and multilingual management
The SLA commits the provider to measurable timelines. Here are typical 2026 commitments.
| SLA commitment | Standard tier | Premium tier |
|---|---|---|
| Guaranteed uptime | 99.5 % | 99.9 % |
| Response time, critical | 24 h | 4 h |
| Response time, minor | 72 h | 24 h |
| Security fixes | Within 7 days | Within 48 h |
| Activity report | Quarterly | Monthly |
| Backup | Weekly | Daily |
In multilingual mode, the main challenge is synchronization: an EN change must trigger the FR and AR updates (with RTL support for Arabic). A good contract states the propagation delay between languages and the cost per translated word or page.
Mini case study
Sarah is head of digital at an industrial mid-cap in London running an EN/FR/AR (RTL) site. She weighs handling maintenance in-house versus a Business retainer at GBP 300/month (GBP 3,600/year). In-house would take about 4 h/month of a GBP 48/h loaded profile, i.e. GBP 192/month, but with no SLA or security on-call. An untreated incident (site down 8 h during a campaign) would cost about GBP 3,000 in lost leads. For GBP 1,300/year of extra cost, the retainer delivers a 24 h response time, security fixes within 48 h and three-language sync, a clearly favorable trade-off.
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FAQ
What exactly does a retainer cover?
Three strands: corrective (bugs), evolutive (new features, within the hours quota) and preventive (updates, security, backups). Beyond the quota, enhancements bill at GBP 300-560/day.
How much is an extra language?
Between GBP 1,300 and 4,000 by page volume, plus 15 to 25 % of monthly maintenance. Arabic adds RTL support cost (interface mirroring) best planned at design time.
What SLA should a B2B site target?
For a brochure site, 99.5 % uptime and a 24-72 h response time suffice. For a site with a client area or critical lead engine, target 99.9 % and a 4 h response time.
Can I cancel easily?
Good retainers are monthly or annual with 1 to 3 months notice. Check the reversibility clause: recovery of access, code and backups with no hidden fees.
Does the retainer include hosting?
Not always. Some tiers include it, others bill it separately (GBP 20-80/month). Clarify this to compare offers on equal scope.
Let's scope your project. Maintenance retainer for a multilingual B2B site, indicative budget GBP 130 to 520/month by tier and SLA, setup within 1 to 2 weeks. 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.
