Oct 04 2011
While there are few, if any, hard rules about how to go about redesigning your site or when to do so, I really think there should be. Just one.
Do not, under any circumstances, take down your current site while having the new one developed.
I've seen my share of sites where either the web designer or website owner (or both) has made the mistake of taking down the old/current site and replacing it with the dreadful "Under construction" page. While it may seem like the right thing to do, it really isn't. At least not if you care about your visitors and your search engine ranking.
Your site, regardless of its current state, likely contains important information that visitors will use. Be it a downloadable brochure, service or product descriptions, contact information, etc., it's likely that the information will be read. Taking access to that info away from your potential visitors is akin to closing a brick and mortar store just because you're remodeling. When was the last time you saw the Gap close just because they needed to rearrange their displays for the new season?
It's that same information that will keep your search engine rankings alive and well (and possibly improving) if you keep your site up rather than taking it all down during development. Search engines feed on content. Not having it is essentially telling them that the content no longer exists.
Are there exceptions to this rule? I think so, but they are very few and far between. Instead, keep your old site up. It'll serve your business better in the long run.