Many houses can be extended without the need for a planning consent.  architecture:ab are experienced in working within the constraints of Permitted Development to maximise the extent (size) of extension possible.  This type of application can be cheaper and quicker than a full Householder Application.

We always gain written confirmation from the Local Planning Authority that confirms that the proposals are within Permitted Development.  This is important in case questions are raised during the project, or at a later date when trying to sell your home.