Do You Need Planning Permission?

Before starting your basement project, you'll need to find out if you need planning permission. This decision mostly depends on two things: whether you're transforming a basement that already exists or digging out a completely new one, and how extensive your proposed changes are.

Renovating an Existing Basement

If you're looking to turn your current basement into a usable living area or simply redecorate it, you typically won't require planning permission.

However, you will need to apply for permission in certain situations. These include instances where you:

• Plan to establish a brand new, independent home within the basement, such as a separate flat.

• Intend to drastically alter how the basement is used, for example, by transforming it into a commercial space to run a business.

• Propose to install a brand new lightwell.

• Make any changes to the exterior look of your house.

Building a New Basement

When you plan to excavate and construct a completely new basement, you will almost certainly require planning permission. This is primarily because such projects typically involve significant disruption from excavation and can noticeably change the external look of your property.

If your new basement design includes adding a lightwell to draw in natural illumination, you should be aware of additional regulations. Lightwells positioned at the front of your property and visible from the street might face more stringent appearance requirements than those situated at the rear or side of your dwelling.

Before you formally submit any application, we strongly recommend that you discuss your proposals with your local planning authority (LPA). They can provide valuable guidance, as many LPAs have specific guidelines for basement depth and overall dimensions, often detailed within their supplementary planning documents (which offer additional local planning policies).