If you are adding an extension to the rear of your home and it is within 2m of a boundary wall or fence then the maximum eaves height should be no greater than 3m.
“In case you were unsure what the ‘eaves’ is – This is the underside of the soffit or fascia that usually holds the rain water gutter for the extension roof”
The height to the top of the roof must not exceed 4m at any point.
This measurement is taken to the highest point of the roof.
If you live in a detached house then your extension can extend beyond the rear wall upto a maximum of 4m.
For semi detached and terraced houses the depth of your extension can be no greater than 3m
Where not on designated land (Article 2(3)) or a site of special scientific interest this limit is increased to 8m for detached houses and 6m for all others.
Please note however that in order to take advantage of these ‘doubled up’ permitted development rights you will need to make an application under the prior notification scheme’ which is a 42 day process in which basic plans and information are submitted into your local authority and your neighbours are consulted and given 42 days to lodge any objections.
Something you would need to consider when opting for the prior approval scheme is that unlike normal permitted development you are not guaranteed approval which is why you MUST apply for prior approval BEFORE any works are carried out on site.
Just one neighbour objection under this scheme would result in Prior Approval being required and that basically translates into you then needing to apply for Planning Permission.
Something else you would need to consider when adding an extension to the rear of your home is the question: what constitutes a rear wall in the first place?
“Well that’s easy, it’s the rear wall across the back of my house right?”
The answer is a not quite as straight forward as this. You see, when defining what parts of a house would be classified as rear wall it was decided that:
The rear wall applies to the rear wall of the building on the day that it was built, or for older properties as it was on 1st July 1948.
This means that if your property benefitted from a side extension or garage added in the 50s, or later then the area behind this would NOT fall under permitted development and would of course require planning consent.