Outbuilding Height

[efunc]

Morning all,

I wasn't sure if this should go in the Building section, the Roofing section or here, but perhaps most sensible in here. I'm trying to build a garden room 2.4m x 3.4m, with a flatroof under Permitted Development. It abuts the neighbour behind it and the other one on the right and replaces the previous shed situated on the same concrete plinth:

The height from the base of the bricks to the top of the firrings is likely to be 249cm at the back, but with the 18mm OSB decking and GRP roof that would then increase to about 252cm. The problem is that I was planning raised edging for the GPR roof which would run down the right and left sides of the roof. It also doesn't include any lead flashing chased into the wall above at the back. Both these elements could come to a further 3cm leaving me with a 255cm high building.

What are my options for keeping it within the permitted development restrictions?

I could reduce the door frame height from 202cm to 200cm or more and gain at least 2cm height at the front. The 6x2 roof joists are going to use a rear wall for support at the back, and that's 227cm high, so fairly fixed. However, is it possible for me to thereby lower the front by 2cm or more so the joists pitch forward? Then I can also use shallower firrings to achieve the same 1:40 fall. Or even make do with a 1:60 fall? At the moment my firrings are calculated to 6cm at the back, but they could be 5cm, or with the front pitched lower then only 3 or 4cm (?)

Any advice would be welcome as I presume this is a common dilemma and there are probably far cleverer solutions!

Thanks all.

 

[tony1851]

Is this actually an 'outbuilding', or is it attached to the house or an existing detached structure. If it's not completely detached, the Permitted Development rules for detached buildings (known in the trade as 'curtilage buildings') don't apply, and you look instead at the rules in Class A (extensions etc).

With regard to the height itself, things like flashings don't apply. If you have in fact to deal with the maximum height of 2.5m for a detached structure, ending up with 2.55m is absolutely nothing - no council will start enforcement on a 50mm transgression.

In the official guidance to LPAs on Planning Enforcement, there is actually a stipulation that 'enforcement may not be appropriate for a minor or technical breach where no harm has occurred'

In anyone's book, 50mm overheight is minor.

(Have you ever woken up in a sweat after a nightmare about the time you once drove at 31m.p.h in a 30 zone? )

 

[efunc]

Hi Tony, thanks very much for your input again. Yes, it is completely detached and about 10m away from the side of my house. The walls in the representation are the side of a neighbours house behind it (in white), and a boundary wall with another neighbour to the right, which is the bottom of their garden. The reason for ensuring it's exactly under 2.5m is that I didn't want to invite any complaints from the said neighbours, both of whom are developers with multiple occupancy flats. I want to ensure I stay off their side of the boundary wall and that the height doesn't poke above, or they suffer any drainage/runoff issues from my flatroof.

Thanks for the advice, I'll crack on then and sleep easy!

 

[garyo]

Is it possible to build a side extension under class A when it's attached to the neighbouring property rather than your own?