20cm set back rule for lofts

[SoConfused73]

We are getting a rear loft built and I am confused about the 20cm set back rule, in particular on how it relates to the side of the house. We have a three-bed semi. The original roof sloped in from all three sides( hipped roof I believe in the technical jargon ). The roof has been removed and a new full-width dormer will be created at the back. So effectively the new roof becomes an inverted V shape with a dormer at the back.

I understand that at the rear, being set at least 20cm back, the dormer wall will be supported by the steel beam. However, I am confused by the sides( section facing shared driveway) and the application of the 20cm rule. If set in by 20cm, it means we are not building on top of the existing side wall, therefore how is the side wall being supported?

I have checked the government guidance but they only give a diagram of the rear face of the dormer which will be supported by the steel beam. Between the builder, the architect and the government guidance, I am utterly confused. I appreciate this seem like a very basic question, but I don’t want to reach the end of the build and the council not passing the dormer loft and being left massively out of pocket. Diagrams or picture would be appreciated on how it should be and what is being measured from where with regards to the side of the house.

 

[^woody^]

The sides don't need to be set in

 

[freddiemercurystwin]

https://www.gov.uk/government/uploa...238/160413_Householder_Technical_Guidance.pdf

 

[chappers]

Is this work being done under permitted development as it only applies to PD. There are easements allowed if it isn't feasible to maintain the 200mm of roof. Sometimes BC will pull you up on it but it's not really their remit but that of the planning department.
But as Woody says it only applies to the eaves and not the verges.

 

[Nakajo]

Also, some local authorities seem less fussed than others... as this image will attest...

 

[^woody^]

Also, some local authorities seem less fussed than others... as this image will attest...

Is that a 20° set back instead of cm?

 

[Nakajo]

I wouldn't like to say what that was. There may be children watching.

 

[tony1851]

Looks like a Frank Gehry job.

 

[^woody^]

TBH, I quite like it.

 

[Nige F]

Put the Mad in Mansard - I particularly like the SVP

 

[dom_k]

If you are doing hip to gable plus big dormer you may well be over your PD limit! Best check it out as full planning may be required

 

[SoConfused73]

To close out my own question, it's as Woody and Chappers said. Loft got its completion certificate.

Thanks to all who took time to respond.

 

[John D v2.0]

Thanks for the update! Although I should pont out the completion certificate is for building regs which is a different department. There's no specific completion for planning permission or permitted development, you just have to take a photo and then wait for it to be unenforceable.