I had an interesting but confusing phone call into the Inspections Dept yesterday. A Lady called for me to inspect her chimney due to severe smoke problems entering her playroom basement area. This home is not new she bought it about 8 months back, originally built in 1994. the past fall she hired a chimney sweep to clean her chimney before using it . The chimney sweep declared that it had never been used. and A OK she has glass doors installed and never uses the fire place till Super bowl night. They are al set when she decides to move a load of laundry from the washer to the dryer when she opened up the door the playroom area was filled with smoke. Evidently the playroom was built afterwards, and the walls erected blocked off any basement smoke preventing it to reach the smoke detector at her stairway. I checked the files and we have no permit on record for the basement build out. Which would have required an additional smoke detector. The Fire-dept arrives and with the aid of huge fans cleared the smoke out the bulkhead exit. Naturally when the fire dept arrives, they bring every truck and create quite a seen in the neighborhood. . After talking to some of her neighbors she finds out others had problems with their fireplaces and chimneys, and that the original builder had to come back and do some repaires. Here is where I am really confused? According to the neighbors, the original builder, told them he fixed the problem which was due to the flues being installed backwards or upside down? There is no backwards or upside down position in installing clay rectangular flues? When the chimney sweep was there cleaning he also recommenced a chimney cap and installed one to keep any animals out. Main points here 1. cleaned chimney the owner has the invoice as proof 2. glass doors installed 3. Animal proof chimney cap installed by chimney sweep Puzzling is the smoke did not back-draft into the room of the fire place but down stairs. The obvious answer is there is blockage. but how ? Chimney sweep cleaned it and capped it , to prevent animal intrusion and blockage The Weather was light rain in the morning, turning colder but only about freezing at game time Should have been cold enough to decent draft. though a bit windy once a clod front passed. Puzzling the fire place is drafting but smoke is filling up the basement area below? Why did it not back draft the room of the fire place if there was blockage? Why fill the basement the floor level under? This coming Wed. I will be doing an investigative inspection. care to hazard a guess as to how the smoke got in the basement ?