Rear extension - single storey when garden is sloping lower than the house floor level

[Chexpar]

Guys,

I have seen similar posts of measuring eaves height on sloping ground for rear extension for
3m restrictions. Any feedback or clarification is much appreciated.

Below are some details -

L-shaped single storey wrap extension with side garage and rear extension.

The floor level is at 0.0.

The garden level is lower at -0.6m.

The house patio is at -0.2m and is 4m long spanning full width of the house.

The patios of neighbouring properties are at -0.2m and -0.06m wooden deck below floor level. Both patios are 4.5m long plus.

The external wall of the extension will be in the garden. For 3m rule, where is the eaves height of external wall roof of extension measured from -

- our house patio
- neighbours patio
- garden level
Or is patio not considered as natural ground level

The application is full planning application. I will attach a picture later.
Rear elevation of existing house with patio and lower garden

 

[^woody^]

The 3m restriction and ground levels are for permitted development, and do not apply for a planning application

 

[Chexpar]

Thanks Woody. Below specification mentions it.


SPD2 generally allows single storey rear extensions on attached houses of up to
3m in depth from the existing rear building line of neighbouring properties. Up to
6m in depth may be acceptable where the extension is set in from the side by
1m for every 1m of additional depth. Roof heights should not exceed 3m for a flat
roof including parapets, and an average of 4m for pitched roofs, and infill
extensions on side boundaries should be no higher than 2m high on the boundary.

 

[^woody^]

For height, the highest ground level is the level to measure from. So, in your case, the ground nearest the house.

And where criteria is not specifically prescribed, there can be leeway - ie "should" is not "must", "generally" is not "always".