Building a garden room, determining my 'ground level'

[britishboy7]

I'm planning a wooden built garden room at the bottom of our garden, about 1ft from both the side fence and rear fence. I know the max height can be 2.5m. Am I right in saying maximum floor area can be 15m2 without needing permission?

what do i use to determine my ground level, to calculate the 2.5m height from? The lower garden (70% of the garden) is paved so i was going to build the room on top of some paving slabs (1 layer high), stood on the existing patio.

 

[LukeB123]

I'm planning a wooden built garden room at the bottom of our garden, about 1ft from both the side fence and rear fence. I know the max height can be 2.5m. Am I right in saying maximum floor area can be 15m2 without needing permission?

No maximum in floor area for planning permission. The only restriction if you are off the Boundary is no more than 50% of the curtilage (the garden) is taken up by outbuildings / structures.

Building regulations may be required, usually over 30m2.

what do i use to determine my ground level, to calculate the 2.5m height from? The lower garden (70% of the garden) is paved so i was going to build the room on top of some paving slabs (1 layer high), stood on the existing patio.

You measure the 2.5m height from the highest part of the land on which the outbuilding is being built. This should be the original land level and not built up.

 

[andrew456]

You measure the 2.5m height from the highest part of the land on which the outbuilding is being built. This should be the original land level and not built up.

So in my expertly drawn example, it would count as the red arrow, not the blue arrow, that would need to be within 2.5m?

 

[LukeB123]

Yeah pretty much.

You shouldn't really include the paving area, unless it is a significant structure in its own rights - then you might judge it by different PD rights anyway (I.E. You can't pave half the garden, put a structure on it and then measure it from the highest point of the paving, if its just a few slabs)

In this piece of artwork, extend the blue arrow straight down to where it would meet the green squiggly line (wherever that would be prior to the paving) and there's your height.

 

[britishboy7]

Thanks gents, and do you think building the 4" x 2" floor framework on top of 1 height of strategically placed paving slabs will be ok?