Planning for decking on a sloped garden...30cm height query

[Kitsmummy]

Hi, I'm hoping there may be someone involved in planning who could answer a query for me.

We're aware that decking does not need planning unless 30cm above ground level height. However the garden in question slopes...it's
An old barn kind of built into a hill and the garden slopes up away from the house, therefore the proposed decking is over 30cm higher than the lowest level of the grass/land that adjoins the house. However it would still be lower than the internal ground level when the wall is knocked out to put doors in.

Could anyone clarify if the 30cm measurement is from the highest part of the land or would it be from the bottom of the house wall (which literally just has hill behind it).

I've attached a very rubbish pic...purple line is suggested decking level. Red arrow shows the downhill slope of the garden towards the house

I hope that makes sense!

I think it's the lowest part of the land you need to measure from

We’ve got 100m2 decking at the back of our house - at the back wall it’s floor level and at the end it’s about 150cm off the ground. We didn’t need planning.

If building under permitted development (no planning permission required) check here: https://www.gov.uk/government/publications/permitted-development-rights-for-householders-technical-guidance/permitted-development-rights-for-householders-technical-guidance#introduction

Which has the following:

Height: references to height (for example, the heights of the eaves on a house extension) is the height measured from ground level. (Note, ground level is the surface of the ground immediately adjacent to the building in question, and would not include any addition laid on top of the ground such as decking. Where ground level is not uniform (for example if the ground is sloping), then the ground level is the highest part of the surface of the ground next to the building.)

Thank you all. I think we'll have to do a pre planning query annoyingly given that the land that adjoins the barn is at the lowest point. Thanks for your help

The bigger the gap from decking to ground the more space for rats.

Why would you put decking there

The 'building' being referred to is the decking is my understanding. So 30cm measured from the highest land where the decking footprint is.

The 30cm is definitely from the building. So if the garden slopes downwards away from the house you can put in decking that ends up much higher than 30cm without planning permission. But if it slopes upwards away from the house, as it appears to here, then you may need pp for even a modest deck.

Thanks, yes it slopes upwards from the house so think may heed po as per bluebell's comment.

As to why we'd want decking...it's not v useable space right now although you can't see it in the rubbish pic. There is about 2 m of grass at bottom level then a slope up and a path so decking would give us around 4m depth of useable space with great views.

How did you manage that, I started a 36m2 deck at the bottom of my garden that starts at ground level and was 1m at the back. Neighbours went mental and we re having to fight for planning permission