Vents were closed.
The pipe that burst was the pipe that fed the outside faucet. It burst on the inside side of the shutoff valve (which was closed and pipe drained) Some how there was a short (~3") piece of pvc. Guess even under the house it got a little cold when outside temps were hitting -30. (not windchill). In the spring I'll be insulating under the house.

After all, it's only money....

btw. since Sep, I was laid off (contract not renewed) and rehired two weeks later by the same client... Today the manager that I've been working for, just informed me that he has been given his two week notice, half the team has been given their notice, and the remainder of the team (includes me, so far) has been reassigned to another manager. This project is way behind, way over budget, and imo, will never provide the anticipated results... This is NOT a good project. Time to re-update resume...