Soil Stack query

[StevieD999]

Hi,

New here as only just found this forum.

My questions are: I have just started doing my loft conversion and I have two soil vents in the loft they are just slightly above the existing plasterboard ceiling (both with AAV fitted) one for the main bathroom and the other for the ensuite. I will be T'ing off the ensuites soil pipe for all the new loft ensuites waste. I am aware that I will need to raise the soil above the flood level for venting purposes etc, is it better for me to run the soil vent outside and have it as a vent rather than with an AAV within the eaves of the loft?
Also can I leave the main bathroom AAV where it is as its in the middle of the loft and to rework it to go outside will be a small mission, this will be lower than the new ensuite sanitaryware. I need to add that after checking my own manhole in the front garden, they both have their own exit into the MH?

I appreciate an help. . thanks

 

[Ermintrude]

Cap one in middle of floor fix two 50mm strap on bosses and run the two 50mm pipes to the location of the loft stack . Tee in above the highest spill over point. You can't really have an Aav under the floor. As for new stack take it out through the roof say convenient position and then with clips and bends run pipe up the roof ( externally) and vent at appropriate location above sky lights. Local building control will confirm. U can reduce the lower stack to 75mm but your not sulu poised to have mega number of bends so 2 50mm makes up for bends.