Measuring building height on sloping ground.

4 Mar 2011
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United Kingdom
My house is on a hill, if you look from the front the ground slopes from the left down to the right. Its a semi and mine is the right hand property.

I would like to put an extension on the back of the kitchen which is on the right side of the house. To avoid planning permission I am trying to stay within the 3m out and I think its 4.5m high (or around that figure).

I plan to level the ground at the back of the house and build a retaining wall inline with the right side of the house, to terrace the garden effectively.

This will give me 2 heights from ground level, the level from the ground behind the house and the dropped level at the right, half a meter or so lower down.

Which height should I be looking at?

The 3m out, would that be 3m to the brick work? Or more likely, 3m to the part that extends the furthest? Say the gutter for example.

Would it be more advisable to go down the planning permission route? If so, maybe incease the size slightly to 3.5m. As the extension will be split into a utility room and a downstairs toilet. So making the two spaces a little more useable.

Thanks Mark
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If you need 3.5 or 4m in depth to make a more practical and useable extension then you should pursue it, the cost need not be that significant in the grand scheme of things (you could even do the drawings yourself if you want) and you may regret not doing so if you do not do it depending what you want to do with the space/achieve with the extension.

For clarity on PD have a read through this:
Height is measured from the highest existing adjacent ground level

Distance out is to the external wall face, and assumes typical eaves details of about 200mm or so

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