Birmingham go into the half-time interval with a 1-0 lead over Championship leaders Reading.
Neither side forced the opposition goalkeeper into serious action in the first 20 minutes, with Adam Federici only having a couple of comfortable efforts to deal with.
He was beaten after 25 minutes, however, as substitute Adam Rooney picked up Nathan Redmond's pass before sliding it first time past the Reading keeper.
Redmond then came close himself, firing a shot from outside the box just over the crossbar as the hosts continued to look dangerous.
The champions had chances of their own towards the end of their half, one effort from Adam Le Fondre having to be hacked off the line by Pablo Ibanez.
Le Fondre then raced through once again and dinked the ball over Colin Doyle in the City goal, only for Ibanez to once more save his side with another clearance off the line.
Ibanez was almost the hero at the other end just minutes later when he met a Townsend free kick only to see his header come back off the post.
As things stand, Birmingham will leapfrog Blackpool into fourth in the table.
