Loft location at a higher point than soil vent

[DavidLoft]

Hi there

I have an existing soil stack on the side of my house. I have extended the house by building a loft.

The loft company ran the waste from the loft over the roof straight into (i.e. closing off) what was the soil pipe - and added an AAV at loft level.

However now I am reroofing and need to move the soil pipe.

Can I convert the main waste back to open vented and run my loft into it as a branch connection EVEN THOUGH the loft itself is higher than the soil pipe vent opening height?

The branch would have the necessary slope and I would be be compliant with 900cm rule.

 

[king of pipes]

A few pictures would help please ??

 

[Last Plumber]

As above pictures help a lot.
The open vent would be better there in my opinion. It needs to terminate 3' above an opening into a building.