Creating a new basement will usually require planning permission, particularly if it affects the external appearance of the property. For example, installing a lightwell to bring natural light into the basement may be subject to stricter design rules if it is visible from the street, especially at the front of the property, compared to those at the rear or side.

Because basement construction involves significant excavation and structural work, permission is often necessary. It’s recommended that you consult your local planning authority early on to understand what is likely to be considered acceptable before submitting a planning application. Building regulations will also apply to a new or conversion of a basement.

Read further guidance on basements.

If you want formal confirmation that the existing use of a building is lawful for planning purposes, or that your proposed development does not require planning permission, you can apply for a Lawful Development Certificate(LDC). An LDC can be useful in situations where you need assurance that a particular use, operation, or development is lawful under planning legislation.

Read more about Lawful Development Certificates.

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Applications for a Lawful Development Certificate can be submitted online to your local council using Planning Portal. You must include enough detail and evidence to support your case; if the information is insufficient, your application may be refused.

Apply online

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To qualify as permitted development some household building work projects – notably extending a house – must not exceed limits to the volume being added.  

In England, the volume allowance mostly applies to loft conversions. You can read more on the Planning Portal. 

Use the volume calculator to find out the volume of several loft conversion and extension types.

Whether you need building regulations approval depends on the type of underfloor heating (UFH) you are installing.

Electric UFH must comply with Part P for electrical safety.This work can be done by a member of the competent persons scheme who can self-certify the work.

Wet UFH must comply with Part L which focuses on the conservation of fuel and power. This will likely require building control approval.

Planning permission is unlikely to be required for the installation of external damp proofing unless the work will change the external appearance of the building or is part of a larger project.

If you live in a listed building you will need listed building consent for any significant changes, this can include external damp proofing. Additional rules may also apply if you live in a Conservation Area or other protected area.

Building regulations approval is not required for installing an external damp proof course (DPC).

Read further guidance on damp proofing.