The building of an extension is certainly going to alter the way that you home looks and part of that process is adding external walls that work with the existing structure, but also possibly changing the existing wall cladding to give a more attractive overall look. In most cases your exterior walls will be exempt from planning permission, but there are cases where planning will be required.
- If you live in a listed building or in a conservation area you will almost certainly need planning permission
- If you want to clad your new or existing walls with stone, pebble dash, render, tiles or plastic and you live in an area of outstanding beauty or a national park you will need to apply
- In all other cases you still need to ensure the cladding or wall covering you choose must be in keeping with the existing style
Changing the look of the outside walls of your home may not always need building regulations approval – but the addition of new external walls as part of your extension probably will. Building regulations use a set of rules to determine if approval is required:
- If more than 25 percent of the exterior walls are re-built, re-rendered, re-clad or re-plastered then evidence of correct insulation will need to be supplied to building regulations inspectors
- If new external wall cavity insulation is inserted into walls you may need them to assess this
- Generally your new walls should be built using the cavity wall system as this provides a better thermal load. Buildings regulations will be checking for this. Solid walls will need special insulation to make them passable
- Wall loads are also incredibly important and will be checked. If your new walls are holding up upper stories or the roof they need to comply with loading rules and possibly having lintels installed
- Weather resistance rules and thermal resistance rules are also taken into account
- Your walls need to meet fire protection rules also and existing walls may need to be upgraded as part of the work to ensure compliance
As you can see, building or improving external walls is a complicated process and while you may not need planning permission for the work, the building regulations rules are onerous. This is one that is best left to your builder.