Denard Span, Anthony Rendon, Adam LaRoche and Danny Espinosa each had two hits and an RBI for the Nationals, who took both games in this short interleague set and won their eight straight against the Astros.
Starter Gio Gonzalez returned after missing close to a month with left shoulder inflammation and did not factor into the decision. The left-hander was reached for four runs on five hits and three walks with six strikeouts over five innings.
Aaron Barrett (3-0) recorded just one out to close the seventh to earn the win.
Jose Altuve supplied two hits and Matt Dominguez drove in two runs for Houston, which has dropped three straight games. Reliever Darin Downs (1-1) was tagged with the loss after giving up a run and failing to record an out in the seventh.