This is the fear that stalls the most rebuilds, and it is a fair one: a site redone carelessly can lose most of its visits within weeks. The reassuring part is that the cause is nearly always the same, and it is fixed before launch, not after.
What actually tanks the traffic
It is neither the new design nor the new platform. It is addresses changing with nobody looking after them.
Your old site had pages that showed up in Google. Each lived at a precise address, something like `your-site.com/our-work`. Google knows those addresses, other sites may link to them, and your customers have them bookmarked.
The new site organises things differently. The page still exists, but it is now called `your-site.com/work`. To a visitor arriving on the old link, that is an error page. To Google, it is a page that has vanished, and eventually it drops it from the results.
Multiply by twenty pages and there is your drop.
Redirects, and nothing else
The remedy is one word: the permanent redirect. You tell the server that the old address has become the new one, for good. The visitor sees nothing and lands in the right place. Google understands the move and carries over to the new page what the old one had built up.
In practice, before any launch:
1. List the old site's addresses. All of them. A sitemap, a Search Console export if you have one, or a tool that crawls the site. 2. Match each old address to a new one. One by one. When a page no longer exists, pick the closest by subject, never the homepage by default: redirecting everything to the homepage amounts to redirecting nothing. 3. Put the redirects in place before switching over, not the following week. 4. Check after the switch that every old address leads somewhere.
That list is tedious and that is all it is. There is nothing technical about it, only method, which is exactly why it gets skipped.
What else you should not lose
Content matters as much as addresses.
- Keep the words. A page that ranks well often ranks because of wording you find too long or too plain. A rebuild that "tightens" the text cuts out precisely what was bringing people in. Rewrite to say it better, not to say less.
- Keep the titles. If a page is called "Emergency plumbing in Mérignac" and it ranks, do not rename it "Our services".
- Keep the pages that work. Look first at which ones bring visitors. They are not always the ones you would guess, and often it is a page you were about to delete.
The three other traps
The staging site left open. While it is being built, the new site lives somewhere. If Google can see it, you end up with two identical sites, and sometimes the wrong one survives. It must be closed to search engines during the work and reopened at launch. The reverse mistake also happens, and it is worse: a site launched while still closed to search engines disappears entirely.
Changing the domain name at the same time. Changing the design and changing the address are two simultaneous moves. If you must do both, do them one after the other.
No baseline. Without a record of before, you will not know whether you lost anything. Write down your numbers the day before the switch.
How long it stays unsettled
Expect two to six weeks of movement even when everything is done right: Google has to revisit each page. Variation during that window is not a failure. What should worry you is a drop that has not recovered after two months, and that is when you go back and look at the redirects.
If your current site is holding you back
A site you cannot edit yourself, unreadable on a phone, or dating from a time when you did a different job: those are three good reasons to rebuild, and none of them justifies losing what it has built.
Tell us what you have today and we will say what to keep, what to redirect and what to rebuild. Written answer within two working days.