Date: 201602
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Flight conditions: VMC
Light: Daylight
Aircraft: Regional Jet 200 ER/LR (CRJ200)
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Cruise
Airspace: Class A ZZZ
ATC / advisory: Center ZZZ
Aircraft component: Service/Access Door
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Pilot Flying; Captain
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Second reporter function: Pilot Not Flying; First Officer
Anomaly: Aircraft Equipment Problem Less Severe
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Diverted; Flight Crew Landed As Precaution
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: I was assigned a repositioning flight.  The previous day; there was an air leak coming from the service door.  [Company] maintenance performed necessary maintenance and closed out the open write up on the air leak.My first officer met me at the operations office; we got to the airplane; and performed our preflight checks.  We started engines; taxied; took off; and climbed to FL320 with no abnormalities.I was fully aware of the leak issue; and kept my eye on the cabin pressure during the flight.  The first half of the flight went uneventfully; but halfway to [destination]; we suddenly heard a loud whoosh sound coming from behind us.  I looked at the cabin altitude; and it was slowly climbing.  At this point it was somewhere in the 6;000 to 7;000 feet range; which was in the normal operating range.  I wanted to check on the problem; so I transferred the controls to the First Officer (FO) and he put his oxygen mask on.Upon checking the service door; I noticed that there was an air leak coming from the bottom.  While inspecting the door; the FO chimed me to come back to the cockpit.  When I got back in; he notified me that we were above 8;000 feet cabin pressure and the CABIN ALT caution message had appeared.  I instructed him to request lower with ATC and descend the aircraft.  In the meantime; I donned my oxygen mask and buckled my seatbelt.  I then took back the controls of the aircraft.We were cleared to a lower altitude by ATC; and started the descent.  At this point; the cabin pressure altitude was still in the 8;000 foot range.  I reduced thrust for the descent; and when I did that; the cabin pressure started to climb quickly.  In less than a minute; the cabin pressure had climbed passed 10;000 feet and the CABIN ALT warning message appeared.At this point I instructed the FO to ask ATC for a descent to 10;000 feet; which was cleared by ATC.  I ran the QRC for [the situation] and descended down very quickly.  Once the descent was established; the FO and I discussed divert options and decided to divert to [a nearby airport].  Upon reaching 10;000 feet; the FO and I came off oxygen.At this point we advised ATC that we would not need any more special handling and were going to continue to a landing.  We briefed the approach and landing and landed uneventfully.Root cause of the event was the failure of the service door to remain sealed properly.More frequent maintenance checks of doors/door sealing.


Second narrative: [Report narrative contained no additional information.]


Synopsis: A CRJ-200 flight crew reported diverting to an alternate after losing cabin pressure at FL320.