Carpenter went 15-of-22 for 203 yards, helping the Buccaneers finish at 2-2. They will start the regular season at home against Cleveland.
Both of Carpenter's touchdown passes went to Arrelious Benn, who had three catches for 33 yards.
Houston's John David Booty was 17-of-37 for 209 yards and two touchdowns. Houston had a 1-3 pre-season record and will open at home against Indianapolis.
Tight end James Casey had eight catches for 81 yards in the loss. Tampa Bay owned a 17-0 halftime lead.