Do I need Building Regs to widen doorway on old single storey extension??

[Ela*B]

Hi all
Hoping somebody can help as I've had conflicting opinions! I have a 2 bed terraced that at some point in the distant past (80s I believe) had a single storey extension added to the rear of the kitchen to make it into a 3 bed with a downstairs bathroom which you entered via a door in the end wall of the kitchen. I'm moving the bathroom back into bed 3 and would like to widen the door way into the single storey extension to make it part of the kitchen. I have removed the plaster above the door frame in the extension (which is the original rear wall of the house) and there is a concrete lintel which runs across the width of the extension - 1700mm. The door frame is currently 700 mm (in the centre of the wall) and I want to widen the opening to 1200 mm approx. As I will only be widening the opening below a previously installed lintel will I require building regs?? as in will it count as structural changes?? Many thanks for any help. Ela

 

[freddiemercurystwin]

It seems Building Regs approval would not be required here, got a photo?

 

[chappers]

It seems Building Regs approval would not be required here, got a photo?

But whether the existing lintel is sufficient to span the increased opening is another matter, though

 

[napoleondynamite]

I would apply to be on the safe side. It is a structural alteration and a BCO will check all is in order / safe.