North West Design Associates

Planning Permission

Will your home extension need planning permission?

Perhaps surprisingly the answer is not necessarily, for you may be able to carry out the work under Permitted Development (PD) rights. Permitted Development allows for minor improvements, such as converting a loft or modest home extensions, to be undertaken without first applying for planning permission. Wales has its own version of these rules.

The latest amendments to the PD rules were brought into force in October 2008 and are available in full on the Planning Portal website.

Not every home has an automatic entitlement to PD rules, for instances if your home stands in a Conservation Area or is listed, then you’re more than likely to need planning permission for even very minor work. So, before making any plans, we would talk to the local planners to find out your home’s status.

Assuming that the rules apply to your house, the ‘original’ rear wall of a detached home can be extended by up to 4m in depth with a single storey extension; or 3m if you live in a semi or terrace. If your proposed new extension will be within 3m of a boundary, then the eaves height is limited to 2m.

If you hope to build a two storey extension (no higher than the house), this can project up to 3m from the original rear wall, so long as it is at least 7m from the rear boundary. It’s also important to note that no extension can project beyond or be added to what is deemed to be the front of the house or an elevation which faces the highway. And a side extension cannot make up more than half your house’s width. With the exception of conservatories, new extensions must be built of materials ‘similar in appearance’ and with the same roof pitch as the main house. You can also convert your loft into a bedroom or extra living space by up to 50m³ in a detached house, or by 40m³ within any other home. Flush rooflights or those which do not project further than 150mm are permitted, but you will need permission to add a dormer window on any roof elevation which faces the highway.