Ronnie Belliard opened the scoring in the second inning. After Jesus Flores lined a one-out single over the head of Houston shortstop Miguel Tejada, Belliard hit a 1-0 changeup from Chad Paronto into the left-field seats.
Paronto, in the game because Astros starter Roy Oswalt left after just one inning with a left hip abductor strain, couldn't find any rhythm. He surrendered another run an inning later after back-to-back doubles by Cristian Guzman and Kearns, and he exited in the fourth.
The Houston bullpen couldn't put a lid on Washington, and the home team blew the game open in the fifth. After Guzman and Kearns reached base, Pete Orr bunted them over. Kory Casto took an intentional walk, and Flores' single scored two and left runners at first and second for Belliard to deliver the knockout punch.
The veteran infielder sent the 100th home run of his career to straightaway center field on a 3-2 fastball from Dave Borkowski, clearing the bases and removing any lingering doubt from the game. The round-tripper gave Belliard his second multihomer game of the season and sixth of his career, and it earned him a curtain call from Washington fans.
"I was just looking for a fastball [on the first home run], and I guess I hit the ball good and the ball went out," said Belliard, who ended the night with five RBIs. "The second one, I was just looking for something down and he just left that pitch right down the middle."
Nationals manager Manny Acta praised Belliard, who leads the club with nine home runs.
"He has provided unexpected power and the knack to drive in some runs," Acta said.
Kearns connected on a two-run dinger on a Borkowski curveball in the sixth. The homer was Kearns' fourth of the year and first since May 6.
Redding put the game on cruise control early. He let the Astros put runners on base in five of his six innings, but he didn't allow any to score. Redding struck out six and walked none.
Redding picked up his first win since May 19, breaking a streak of nine straight no-decisions. Redding said using his fastball to get ahead in counts "set the tone" for him on Friday.
"We have so many good, supportive, patient fans. I think they deserve a few nights like this."
-- Nationals manager Manny Acta
The veteran right-hander said there were just a couple of negatives to his outing. The first was his pitch count, which reached 114 through six innings. The second? He would've tied a Major League record had he gotten a 10th straight no-decision.
"I wanted to go in the record book," Redding said with a laugh. "No, obviously it feels good to get a win."
It was a momentous night for Shell as well. Because the pitcher worked three innings, he registered his first career Major League save and the first three-inning save in Nationals history.
Shell stood in front of his locker after the game with the ball in his hand -- obtained for him by clubhouse manager Mike Wallace -- and talked about the feat. As he spoke, he turned over the ball, which was inscribed with the winning pitcher, Shell's pitching line and pitch count, the date and the opponent.
"After the game, they said I had a save, and I didn't know," Shell said.
The only real bad news of the game came in the third inning, when Dmitri Young left with lower back tightness after fouling off a pitch from Paronto. Orr pinch-hit for Young, whom Acta listed as "day-to-day."
Acta said he felt his team was due for a win like the one it got Friday night, after "having to burn every brain cell" for some close victories recently. He credited the fans -- 33,653 showed up Friday -- for sticking with the team through their summer of struggle, and he said they deserved the win as well.
"We have so many good, supportive, patient fans," Acta said, "I think they deserve a few nights like this."