Leanto 2.5m height, which side do I need to measure from?

[Bodgit or Dodgit]

Building a leanto off the read wall of the house approx 6m x 1.8m. That is the slabbed area currently fitted.
I intend on going as wide as possible leaving just enough room to access the soil pipe on the one side and
very little room on the other side.

Currently just a small leanto approx 1.8m wide and 1.2m deep, it does keep the rain off and allows us to have
the back doors open longer.

The current leanto is on a level area with a small slope away from the house but to the side it dips away approx
3 brick courses (170mm)?? which may explain why they only made it that wide.

If I can measure the 2.5m from above the back door area then I can build over the current unit keeping the dust
and weather out but it's tight, if I have to measure from the lowest point then the slope on the roof will be
reduced greatly.

After searching several forums I found posts where you all know your stuff.

Many Thanks.

 

[freddiemercurystwin]

Measure from the highest level as defined in the technical guidance on page 6: https://assets.publishing.service.g...cdb2c9e9/190910_Tech_Guide_for_publishing.pdf

 

[Bodgit or Dodgit]

"Note, ground level is the surface of the ground immediately adjacent to the building in question.

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"


Copied from page 6 so that answers my question and makes enlarging it easier.

Many Thanks.