Planning permission is often required when extending your property, but there are exceptions under Permitted Development Rights (PDR). Whether you need planning permission depends on the size, type, and location of the extension, as well as the property itself. Here’s a general guide:

When Planning Permission is

1. Exceeding Permitted Development Limits

Extensions that exceed the size limits for PDR (e.g., rear extensions more than 4-8 meters deep for detached houses, or 3-6 meters for other houses, depending on prior approval).
Side extensions wider than half the width of the original house.
Extensions that cover more than 50% of the land around the original house.
Extensions higher than the highest part of the existing roof (for loft conversions or dormers).

2. Height Restrictions

Single-story extensions taller than 4 meters.
Multi-story extensions or those closer than 7 meters to the rear boundary.

3. Materials

If the materials used are not similar in appearance to the existing house.

4. Location

Properties in designated areas (e.g., conservation areas, Areas of Outstanding Natural Beauty, National Parks, or World Heritage Sites) often have stricter rules.
Listed buildings almost always require planning permission for any extension.

5. Balconies, Verandas, and Raised Platforms

These usually require planning permission.

6. Forward of the Principal Elevation

Extensions that extend beyond the front of the property (e.g., front porches over 3 square meters or taller than 3 meters).

7. Flats and Maisonettes

Extensions to flats or maisonettes almost always require planning permission.

8. **Article 4 Directions**:
– Some local authorities have removed PDR through Article 4 Directions, meaning you’ll need planning permission even for small extensions.