Solihull is physically easy to extend in and legally harder than almost anywhere else on our patch, and the gap between those two facts is where projects go wrong.
The houses have space around them, the construction is conventional and the plots take a substantial addition comfortably. What decides the project is which of three constraints applies. If the property is within the affected part of the Olton Conservation Area, the Article 4 direction has removed permitted development rights for most householder development, so an application is needed for work that would elsewhere need nothing.
If the property is in the Green Belt, which covers most of the undeveloped borough, an extension is tested against whether it is disproportionate to the original dwelling, and that test bites on size rather than on appearance. If neither applies, the ordinary rules operate and a single storey rear extension of up to four metres on a detached house or three on a semi can fall within permitted development.
The trees are a fourth consideration that cuts across all three. On a plot with mature planting the buildable footprint is frequently set by root protection areas rather than by the planning envelope, and it is far better to design around that at the start than to redraw at week six.
There is also the larger home extension route on unlisted, unaffected property, allowing up to eight metres on a detached house or six on any other by prior approval, with neighbours notified and an answer in about six weeks. On Solihull plot sizes that is often genuinely usable.
Our extensions work is set out in more detail there, including how the Building Control inspections fit around the build.