Roof abutment design detailing for a house extension - what are the options?

Single storey house extension pitched roofs usually abut the existing house wall and, as such, offer a greater choice of design options for the client from a simple lean-too roof to a multi-pitched fully hipped pitched roof. However, when a new extension pitched roof has to abut and interconnect with the existing house pitched roof the design options for the house extension pitched roof may not be that great.

This is due to simple geometry where the existing roof shape and pitched will normally dictate the shape and whether or not the new house extension pitched roof will incorporate gable ends or is to be a fully hipped roof.

The only real exception to these two choices are for when the house extension is quite simple - perhaps something like a 4M wide x 2M deep two storey rear extension when the roof design could be a simple cat-slip roof of the existing roof slope over the extension area. This will create scaling ceilings within the extension which could interfere with the walking area of the extension but can be mitigated with the use of a short dormer window for example.

The aim should be to create an extended property that has interesting roof lines all with matching roof pitches rather than large areas of monolithic tiled roof slopes of no interest, shape or shading.