Narrative:

Shortly after takeoff; I noticed cabin was climbing at about 2;000 FPM. I checked aircraft panel and outflow value position and all were normal. Since cabin was climbing past 8;000 feet; I told ATC we needed to descend to 10;000 feet. ATC cleared us to descend and turn. Flight attendant called on interphone and said she saw a large gap in the door seal of door 1L with very loud air noise. I decided to return to [departure airport]. After running checklists and notifying company and passengers; we landed uneventfully.

Google
 

Original NASA ASRS Text

Title: B737 Captain reported noting cabin pressure problems and a report from his flight attendant of door seal problems; they returned to departure airport.

Narrative: Shortly after takeoff; I noticed cabin was climbing at about 2;000 FPM. I checked aircraft panel and outflow value position and all were normal. Since cabin was climbing past 8;000 feet; I told ATC we needed to descend to 10;000 feet. ATC cleared us to descend and turn. Flight attendant called on interphone and said she saw a large gap in the door seal of door 1L with very loud air noise. I decided to return to [departure airport]. After running checklists and notifying company and passengers; we landed uneventfully.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.