1.   From the gully a pipe leads to an inspection chamber which May also have the soil stack connected to it.

2.   A. Yes sir, those gases do, indeed, waft down from the soil stack when the wind is right.

3.   I have already extended the soil stack without success.

4.   Sewer gases show up in the back yard from the soil stack that goes through the roof.

5.   Soil stacks and valleys have metal flashing and roofing cement to make them watertight.

6.   The extension of the soil stack may have helped, but not enough.

7.   Would it be possible that a nail was driven through the soil stack, and sewer gases are coming in?