When science departments are designed for new builds, or are to be refurbished or moved to other parts of the school, design of preparation areas should be a major feature. It is vital that the brief contains everything that is needed including, in particular, a chemical store. But no matter how well a brief is specified, the people who actually design and build the new science accommodation, or adapt existing accommodation, have been known to ignore parts of the brief, add things that were not there, over- or under-specify equipment (especially ventilation) and generally make mistakes that put users of chemical stores at risk. This article presents examples of what to look out for, in order to prevent them happening to the science department.