Joomla to Next.js Migration for an Architecture Practice in London

The verdict in three sentences

A site on Joomla 3, whose official support ended in August 2023, has become a legal and commercial risk: the 2 critical vulnerabilities published in 2025 remain without an official patch and a portfolio of 6 MB images penalises every mobile visit. A migration to Next.js with Sanity between 15,000 and 28,000 GBP solves security, cuts image weight by four with AVIF and makes the 180-project portfolio genuinely browsable. The only real risk is search rankings: with a well-built plan of 900 301 redirects, traffic loss stays at 5-10% for 4 to 8 weeks.

Stay on Joomla, upgrade or migrate

Three options exist. Upgrading to Joomla 5 looks cheaper, but it often means rebuilding the template and replacing abandoned extensions: the real cost approaches a migration.

For a practice whose portfolio is the main sales argument, Next.js wins: project pages are pre-generated, served from a CDN and images are resized automatically for each screen. Sanity adds a structured project model (location, client type, area in square metres, awards) that architects can edit without a developer.

The image workload: 180 projects, 6 MB per photo

An architecture project has 12 to 20 photos on average. With 180 projects, the practice stores about 2,700 images, often exported as full-resolution JPEGs.

Converting 2,700 images is automated: allow 1 to 2 days of work, plus a visual check of the 30 flagship projects, as AVIF can affect some sky or concrete gradients.

The redirect plan and protecting search rankings

Joomla URLs such as /index.php?option=com_content&view=article&id=123 must all point to a clean address. The plan has four steps: extract the 900 indexed URLs (Search Console, sitemap, server logs), map each one to its new URL, run automated tests on every redirect before switchover, then monitor 404 errors for 8 weeks. This work represents 2,500 to 4,500 GBP of the budget, and it is the item you should never cut.

Mini case study

Oliver, partner at a 9-person architecture practice in London, receives 14 project enquiries a month through his Joomla site. He commissions a Next.js and Sanity migration at 21,000 GBP, including 3,800 GBP for redirects and 2,200 GBP for images. Traffic dips 7% for 5 weeks, then exceeds the original level by 22% in the fourth month, thanks to LCP falling from 6.1 s to 1.6 s. Enquiries rise to 18 a month. With 1 extra commission signed every two months, at average fees of 35,000 GBP, the annual gain is about 210,000 GBP in fees, for a first-year cost of 23,400 GBP including maintenance.

FAQ

Is a Joomla 3 site really dangerous?

Yes. With no patches since 2023, it exposes the practice to defacement or a leak of contact form data, a UK GDPR issue. A web application firewall at 15-30 GBP a month reduces the risk but does not remove it.

Will we lose our search rankings?

A 5 to 10% dip for 4 to 8 weeks is normal. It only becomes lasting if important URLs are not redirected, hence the check of all 900 addresses.

Can we publish new projects without a developer?

Yes. Sanity lets you add a project in 15 to 20 minutes with photos, drawings and a technical sheet, automatically converted to AVIF.

How much does Next.js hosting cost?

Between 0 and 25 GBP a month for a practice of this size on a static host with CDN. Sanity's free plan covers small teams, with paid plans from about 15 USD per user per month.

What timeline should we plan?

8 to 10 weeks: 2 weeks of audit and mock-ups, 4 to 5 weeks of development and migration of the 180 projects, 2 weeks of acceptance and redirect testing.

Let's scope your project. We audit your Joomla site and price the migration of projects, images and redirects, for an indicative budget of 15,000 to 28,000 GBP and an 8 to 10 week timeline. Detailed quote within 48 h. WhatsApp +221 77 596 93 33.