For our customer we need to develop a brand new website which will replace the current one.
He wants to remove the current 'ugly' site completely and show an underconstruction page untill the new website is ready to launch.
The underconstruction page will contains a little text about the company, contact details, ...
We would redirect all traffic to this page using a 302 redirect. Is this bad for SEO because he already has a lot of traffic and good positions for top keywords? We think this will drop and therefore want to convince the customer to still use his current website untill the release of the new one.
When the new website is launched, all current urls will be redirect with a 301 to the new urls.