Ok, I am looking for help with sewer gas in my basement. My house is approximately 55 years old. I have a ranch house with two full baths (stacked). The gas appears to be coming from the stack pipe (cast iron) which is just outside the basement bathroom. I have checked the basement bathroom several times and don't believe the gas is coming from there. Also, all drains are unctioning correctly. In addition, only the upstairs toilet is vented, there is no vent pipe that ties in from the downstairs. I am wondering if cast iron joints go bad as in dry out or shrink ? I do not see any evidence of fluid leakage at this time.

Thanks for any help you can offer

Check for drain traps in basement, floor, sink,etc. if they are not used much they dry outand will smell. Just pour some water down these drains to fill the traps znd that will solve your problems

MMm. I wish it was that easy, I already checked all floor drains, and there are none in the vicinity of the smell source. Also the lower bathroom is used daily.

If you have a bath room sink in the basement bath then,chances are, your toilet's vented. Smells and noises are the hardest to track down if you're not there to do it. Is the smell worse after you flush? Some times a wax seal will prevent water from escaping but not sewer gas. Regards, Tom

I have looked over the entire system, ceiling removed etc. and there is no downstairs vent what-so-ever. I have checked both the shower drain and toilet (very closely) and it does not appear to come from there. Does not matter if after flush or hours later it seems.

Your only other option would be to call in outside help. Good luck, Tom

I guess my main question is, is it common for cast iron joints to shrink and/or leak ? And can they be repaired easliy if so ?

Cast iron lead and okum joints do not, as a rule, shrink and allow sewer gas to escape. However, opening up a wall and smelling might prove me wrong. Tom

Ok, I have located the source of my sewer gas. At the base of my stack(cast-iron) where it goes through the floor it is mortared into terra-cotta it apears; and the mortar joint has cracked up. So I guess my new question is, is there a better way to make that joint now? Or should I just use mortar again?

If this were my call I would CAREFULLY chip out the old motar,(Terra-Cotta's very brittle), and replace with new mortar. I would then paint the joint with roof cement for additional insurance Good luck, Tom