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

 

[snowhead]

A vented stack will always be better than an AAV.

AAV's need to be accessible.

The risk of flooding from the Bathroom AAV is nill, you'd need to have a blockage in the main drain and push water back up the stack with the AAV in, from the ensuite stack.

Given the amount of work you will be doing, taking the Vent through the roof or side wall (if there is one) won't be too much trouble.
If you go that way watch out for the height of the vent and adjacent windows / roof windows.

 

[StevieD999]

Thanks snow head, tbh I was always hoping that an external vent would be better. I will probably go through the outside wall, as if I go through the roof, i'll be quite close to the bathroom velux. Do you know the min distance from an opening the vent needs to be?

 

[StevieD999]

Alos I assume that I can just come out the wall and fit a vent horizontal rather than vertical like the AAV?

 

[stevetheplumber]

basic rule is one metre above any openings or three metres away so if side wall is 3 m away from windows just turn it up outside

 

[Kay101]

create a full soil stack mate, its rare to have 2 aavs? not allowed unless theres a full vent at the head of the system