We have lived in our house for 8 years and until recently have never had a problem with sewer gas in our house. We have had the pipe actually frost over. I have been on my roof at least once a week this fall and now into the winter to break the ice/frost loose. This summer we added a doormer to our house and it is right next to the vent pipe. I was thinking that if I were to raise the pipe a little this would solve the problem. I don't know but it is getting my family sick. And I do not like heights.