Corner returns on new extension.

[huw169]

My new extension juts out from the house and has a centrally located patio door.
What is the minimum distance from the corner of the extension to the door frame? I have been told this is 500mm external, but have nothing to substantiate this.

Thanks
Huw

 

[mikric]

3 brick external return (665mm) is min required without calcs or windpost etc

 

[huw169]

Thanks mik
I will check it out.
Huw