A permitted development right (Class ZA) was introduced in August 2020 and allows vacant and redundant free standing commercial and residential blocks (must have been built prior to 31 December 1989) to be demolished and replaced with a new residential building. The replacement building can be up to 2 storeys higher than the original, providing it is built within the footprint of the existing building, and the overall finished height does not exceed 18m above ground. The permitted development right is subject to prior approval from the local planning authority – matters for prior approval are many, and include highways impact, contamination, flood risk, external appearance, natural light to the new residential, amenity impact on surrounding occupiers, impact of noise from existing commercial uses potentially affecting new residential, heritage and archaeology matters.
There are many circumstances where new PDR will not apply and full permission will be required. These include sites within Conservation Areas, Sites of Special Scientific Interest (SSSI's), listed buildings and their curtilage, scheduled monuments, sites where the building has a footprint over 1000 square metres.
The full regulations can be found here: https://www.legislation.gov.uk/uksi/2020/756/article/4/made