A website carries no printed expiry date. It degrades quietly: a feature bolted on in a hurry, a framework nobody updates any more, standards that move without you. Then one day the cost of a fix exceeds the cost of a whole page, and the question is no longer “should we rebuild?” but “why did we wait?”.
The difficulty is that the drift is invisible from the inside. You know your site by heart and compensate for its faults without thinking. Your visitors simply leave. Here are the seven objective signals that should start the conversation — and how to judge the size of the job.
1. Your Core Web Vitals are in the red
The most measurable signal. If your LCP exceeds 2.5 seconds, if the page jumps as it loads (unstable CLS), or if it lags on the first interaction, Google knows — and so do your visitors. Performance is no longer a technical detail: it governs both search ranking and and bounce rate.
When a site accumulates plugins, third-party scripts and unoptimised images over the years, it hits a ceiling no isolated optimisation will break. Performance debt is structural: it is settled at the root, not patched.
2. Your conversion rate is falling for no visible reason
Traffic holds steady, but enquiries, sales or sign-ups erode. That is the classic symptom of a site that has stopped keeping pace with its audience: journeys too long, dated forms, confused information hierarchy, nothing to reassure.
Expectations rise constantly. What converted in 2021 feels laboured today. If your commercial numbers slip while acquisition holds, the problem is rarely the advertising: it is on the page.
3. The design no longer reflects your positioning
Your offer has matured, your prices have risen, your clients are more demanding — but the site still tells the story of the company you were three years ago. When the perceived level of the site sits below the real level of the work, you lose the best prospects before the first conversation.
At the premium end this is fatal: a site that looks cheap disqualifies a high-end position within seconds. Design is not decoration: it is the first proof of your standards.
4. The mobile experience is endured, not designed
Most of your traffic is on a phone, but the site was designed for desktop and “adapted” afterwards. Tap targets too small, text that needs zooming, temperamental menus, images that overflow: if the mobile experience looks like a degraded desktop, you are letting your main audience go.
A modern site is designed mobile-first. Retrofitting a site that was not is usually closer to rebuilding than to adjusting.
5. Your search ranking is slipping and the structure no longer holds
Positions slide, organic traffic melts away, and every attempt at optimisation runs into a rigid architecture. Badly structured headings, inconsistent URLs, no structured data, content that cannot be organised cleanly: technical SEO is built into the foundations, not onto the surface.
When the base is not built for search you hit a ceiling. No content strategy compensates for a failing structure for long.
6. Technical debt makes every change painful
The clearest signal for a team: the smallest change takes three times too long, breaks something else, or requires that one thing nobody must touch. A CMS overloaded with extensions, obsolete dependencies, code stacked up by a succession of suppliers: the site has become unmanageable.
At that point you pay an invisible tax on every change. A healthy base pays for itself quickly: it turns multi-day jobs into a few hours of work.
7. Your site is not accessible (and the law is moving)
Accessibility is no longer a moral option: it is a regulatory requirement. With the European Accessibility Act in force since 2025 and the RGAA obligations, an inaccessible site carries real legal exposure — quite apart from the users it simply shuts out.
Insufficient contrast, impossible keyboard navigation, no semantic structure, images without alternatives: on an old site these are rarely fixable one at a time. Accessibility is designed in, not added on.
Redesign or rebuild: how to decide
Not every signal leads to the same job. The right question is not “how old is my site?” but “how many signals are lit, and do they touch the surface or the foundations?”.
- A redesign (surface) is enough when the technical base is sound but the dressing is dated: design, content, journeys. You keep the engine and change the bodywork.
- A rebuild (foundations) is required when the signals touch the base: structural performance, technical debt, architectural SEO, basic accessibility. Repair then costs more than rebuilding properly.
Simple rule: one or two surface signals? A targeted redesign. Three or more touching the foundations? Start from a fresh base. Patching a failing base is investing in a depreciating asset.
Where to start
Before touching the design, put the numbers down. A rebuild is steered, not guessed.
- Measure what exists: Core Web Vitals, conversion rate per page, search positions, an accessibility audit. You will know exactly which signals are lit.
- Rank by commercial impact: a sales page that under-converts outranks a little-read blog. Rebuild what earns first.
- Protect the search equity: map the URLs, plan the redirects, keep the content that performs. A badly steered rebuild can erase years of ranking.
- Decide the scope with your eyes open: the data will tell you whether a touch-up is enough or a rebuild pays better.
A rebuild is not an aesthetic expense: it is an investment in the commercial performance of your most visible asset. The moment to start is while the signals are still legible — not once the site has already stopped converting.