Some extensions and alterations to your home can be carried out without requiring planning permission; this is known as permitted development (PD). Household planning rules are complicated but there are tools we can recommend to help you work out if you do need to apply for permission to do it.
These tools will help you decide if you need to apply for permission. They do not, however, give you a definitive source of legal information.
The Planning Portal can help you explore whether you need permission for a particular project. You are also able to find out about common householder projects, with mini-guides and case studies. They also have a host of interactive guides to planning rules relating to common projects and the planning laws that relate to them.
While it should be possible in most cases to decide whether or not a proposed project qualifies as permitted development (PD) there will inevitably be instances where the decision is less clear cut. If there is any ambiguity or question over whether your proposal passes the permitted development tests you have a number of options. It may, for instance, be possible to alter your plans to ensure they meet PD limits and conditions. For peace of mind you may choose to apply for a Lawful Development Certificate (LDC). This is not the same as planning permission but is proof that your household building work is lawful. If you should later want to sell your property an LDC may be helpful to answer queries raised by potential buyers or their legal representatives. As such, it is important that all paperwork and records relating to your property are clear and up to date.
You can apply to your local council for an LDC using the Planning Portal - How to Apply service. You will have to pay a fee.
With all building work, the owner of the property (or land) in question is ultimately responsible for complying with the relevant planning rules and building regulations (regardless of the need to apply for planning permission and/or building regulations approval or not). The Planning Portal has further details on your responsibilities.
Planning permission and Building Regulations approval are two separate things. Please visit the The Devon Building Control Partnership website for more information.