Exempted development means work that you are allowed to carry out without applying for planning permission. Many attic conversions fall into this category, but not all of them, and the detail matters. Whether your project is exempt depends on exactly what you are doing to the roof and where the house sits.
As a general rule, converting the attic within the existing roof shape is usually not something that requires permission by itself. The picture changes once you alter the outside of the roof. A modest dormer to the rear of a house is often exempted development, whereas a dormer to the front, or one facing a public road, or built on the roof plane facing the street, generally does need planning permission. The exact position, size, and orientation all feed into whether an exemption applies, which is why it is case specific.
Some homes have fewer exemptions than others. If your house is a protected structure or is in an Architectural Conservation Area, you usually lose many exemptions and need permission and extra care.
Because the rules are nuanced, we do not encourage anyone to assume their project is exempt. The reliable way to confirm it is a Section 5 declaration from Meath County Council, which gives you a formal answer in writing. This protects you at sale time and gives peace of mind. We can advise on whether this step is worth taking for your home. Take a look at our planning guide, check whether your space works with our suitability checker, or arrange a free assessment. Note that exempted from planning does not mean exempt from Building Regulations, which always apply.