Wiktionary
building up
vb. (present participle of build up English)
Usage examples of "building up".
You've felt it, like a thunderstorm building up on a hot afternoon Beyond the woman, at the Carvers' house, were two more bodies.
Now, though, he simply looks across the street, letting his eyes move slowly from the E-Z Stop to the next building up, from that one to the one where the kids were playing Frisbee when he turned on to the street, and then on to the one directly opposite them, the one where Jackson must have gone to ground when the shooting got too hot.