You will not need to apply for planning permission to paint or maintain the external walls of your flat or maisonette. However, in some areas these rights have been removed (by way of what is known as an Article 4 direction).
If you are a leaseholder, you may first need to get permission from your landlord, freeholder or management company.
If your flat is a listed building, you will need listed building consent, unless it is repainting in the existing colour, and you should contact your local planning authority to determine this.
Works to a listed building that affect its special historic character without consent is a criminal offence.
If you want to re-render or replace timber cladding to external walls, the building regulations may apply depending on the extent of the work.
Where 25 per cent or more of an external wall is re-rendered, re-clad, re-plastered or re-lined internally or where 25 per cent or more of the external leaf of a wall is rebuilt, the regulations would normally apply, and the thermal insulation would normally have to be improved.