The most common way to structure an intranet site is according to an organisation's structure - its departments. Although this approach appears to make sense, a problem arises when users don't know under which department's remit their issue/query falls.
This issue will, of course, become increasingly problematic with larger organisations that may have higher staff turnover rates and/or more complicated structures.
The only real way to be confident in your site's structure is to conduct card sorting sessions, which will actually find out how employees perceive/think about the site's content.
We would generally recommend not to introduce sub-sites unless there is a compelling business case for doing so. Offering sub-sites (according to country or department, for example) can be a good way for an organisation to show sensitivity to such these groups. It does however have the disadvantage of increasing the number of potential places a piece of information might be.
Designing intranets
The intranet should look and behave in a consistent way (rather than, for instance, different departments having radically different graphic designs and navigation systems). Having an intranet that changes its appearance and behaviour between sections disorientates users and can introduce doubts into their minds as to whether or not all sections are as reliable and current as each other.
A good solution can be to create a standard page template with certain fixed characteristics, such as:
* Font
* Navigation
* Graphic design
* Page structure
Another interesting point we have noticed from usability testing studies is that an organisation's intranet should be easily and quickly distinguishable from its public-facing website (i.e. look different). Failing to do this can lead to employees becoming confused as to which 'world they are in' (and could even lead to customers being sent inward-facing and commercially-sensitive documentation).
