Soil stack, adding a new waste.

[SMB]

Hi,
I am remodelling my bathroom.
i need to add an extra waste pipe to the soil stack. However there is very little room to get s strap + adapter onto the vent pipe if there is to be a fall of the new waste pipe.
Below there is a tee to take the soil pipe from the toilet soil stack. There is a ring on the bend of the tee that looks like it can take a glue in adapter for the 40mm waste.
Is it bad practice to have a waste pipe joining the tee at the junction of the pipe from the toilet?
Many thanks SMB

 

[Howsie]

Hi SMB, a picture would be helpful here in order for us to advise accordingly.

 

[SMB]

The space between the joists is being filled with celotex. I know that I could leave the celotex out o there is extra space for the pipe, but I would rather have a complete layer of celotex.
Anyway a photo.
Thanks Howsie for taking the time to reply.
Sorry, the picture is upside down, don't see the controls to rotate it. When I took the photo it was the correct way round. OK I am a Luddite.

 

[Ch4 plumbing]

Hi SMB, that should be fine to do what you describe.