I've got a job that has a grate or trough drain along the side of a garage and it's not butted up against the brick wall very well, so water is getting into the garage from behind it. I used a silicon rubber caulk earlier in the year and now it's coming detached from the drain which is grey pvc. Our temps are in the 20-30's right now. Any suggestions on what might work better.
Sonneborn NP1 is a urethane expansion joint sealant that might work for you. It holds to brick and cement pretty tenaciously, but if you are having movement due to frost, you likely won't get anything to hold permanently.
Instead of running a gigantic bead, you'd use backer rod to fill the space, and use the sealant to cover the backer rod.