Barnes headed home Brad Davis' free kick in the 15th minute, ending Houston's 274-minute scoring drought. Ricardo Clark doubled the lead for Houston in the 72nd minute and Rob Lovejoy capped the scoring in the 80th. The Dynamo (2-2-2) snapped a four-game winless streak despite Montreal controlling the possession for most of the game.
Tyler Deric earned his third shutout of the season with five saves.
The Impact (0-2-2) remained out of rhythm in the MLS season while in the middle of their historic run to the CONCACAF Champions League final. Montreal travelled to Costa Rica for the second match of the CCL semifinals Tuesday night and beat Alajuelense with the away-goals tiebreaker.