Water ingress at air admittance valve at top of soil stack

[GRC]

Noticed damp patch on ceiling, and investigation in attic revealed a drip from the top section of the soil stack, above the level of all bathrooms.

Air admittance assembly is at pitched roof level, then flexible pipe, connecting to solid pipe which takes a few right-angle bends before descending to the en-suite.

There's no sign of leakage around the flexible pipework or at the roof, it seems to be coming down inside the pipework, then leaking out from one of the right-angle joints on the solid pipework.

Do I call a plumber, a roofing contractor, or both?

 

[Blagard]

A standard soil and vent stack will usually be open to the elements and rain can and does get in from the top.

If you have an air admittance valve on top I suppose rain could leak into it

If sounds a rum installation with a leak on a connection, so either fix it yourself or call a plumber. At that level you are really only dealing with drips so usually an easy DIY job.

A photo of the installation would help for more informed advice.