Toilet into vent stack/Alternative to vent stack?

[Del-inquent]

I have no idea what is and isn't possible on this front, I'm just trying to get an idea on how to move forward.

At the moment we have a very odd dog-legged vent stack that runs up the outside of our chalet bungalow, goes along inside the eaves, then up between the rafters (sandwiched between the felt and the plasterboard ceilings). In the diagram below the "T" is currently just an elbow pointing left

We'd like to fit an upstairs bathroom but the vent stack is in about the only place that a downpipe can be. Can we do something along the lines of the below? Can we get rid of the left hand section by any means? There is zero space to form any other sort of connection that I can think of.

I'm open to any and all suggestions at the moment!

[Temp]

You might be able to replace the left hand side and the vent with an Air Admittance Valve (AAV) in the bathroom on the top of a short stub stack. This should be higher than the wash basin overflow. Can be hidden in boxing but should be accessible in case of maintenance.

 

Building Control normally prefer one open vented stack like you have now but don't think they are mandatory any more. They used to insist you had one open stack but any others could have an AAV.

 

 

[Del-inquent]

3 hours ago, Temp said:

You might be able to replace the left hand side and the vent with an Air Admittance Valve (AAV) in the bathroom on the top of a short stub stack. This should be higher than the wash basin overflow. Can be hidden in boxing but should be accessible in case of maintenance.

 

Building Control normally prefer one open vented stack like you have now but don't think they are mandatory any more. They used to insist you had one open stack but any others could have an AAV.

 

 

Would it be possible to have the AAV emerge above the roof outside? I simplified the drawing a little, the new bathroom would be located in the rear dormer, the lower part of the stack runs up the outside of the build below the rear dormer, along in the eaves, wobbles around a bit and then up between rafters. If the AAV could go through the top of the eaves and end below the bathroom windows we could save a LOT of hassle. Or, if that's not possible, would the second option on right work?

 

[Temp]

9 hours ago, Del-inquent said:

Would it be possible to have the AAV emerge above the roof outside? I simplified the drawing a little, the new bathroom would be located in the rear dormer, the lower part of the stack runs up the outside of the build below the rear dormer, along in the eaves, wobbles around a bit and then up between rafters. If the AAV could go through the top of the eaves and end below the bathroom windows we could save a LOT of hassle. Or, if that's not possible, would the second option on right work?

 

No don't think AAV are rated for outdoors. Normally if you can get the vent pipe outdoors you can get it far enough away from windows that it can be open vented. 

 

What you have drawn on the right is fairly standard. The short/stub stack and AAV are either boxed in in the corner of the room or sometimes a concealed cistern is put in the boxing as well.

 

Our house is a 1&1/2 storey house with bathrooms in rooms with dormers. In one room we have a Geberit concealed cistern in the same boxing as the stub stack and AAV. The WC pan is a floor mounted back to the wall design. In another similar room we have a Geberit frame with integeral cistern and a wall mounted pan. 

 

Edited Friday at 22:33 by Temp

[Susie]

You can get external AAV

https://www.floplast.co.uk/article/external-air-admittance-valves