Shower Drain Frozen
The photo lower right shows the shower pipes running through an enclosed wall space.
Shower drain frozen. Salt is very good for melting ice. Pour 1 cup of vinegar down the drain this will cause a chemical reaction with the baking soda which will. Run hot water into the drain.
Given the facts you just presented your drain trap was absolutely frozen. Pipe freezing is a particular problem when pipes are run through outside walls uninsulated or under insulated attics or crawl spaces. Vinegar reacts with soda causing it to sizzle and bubble.
If you have an air compressor aim the air stream from a nozzle down the drain. This combination will also remove stubborn debris like dirt lingering clumps of soap etc. Boil 2 to 3 gallons of water with 1 cup of salt.
Figure an hour or so so don t have the air coming out full blast just about 1 4 1 2 way on the nozzle. Dump 1 2 cup of baking soda down the drain. How to unthaw a frozen shower drain step 3.
Every winter the pipes would freeze sometimes bursting into the garage ceiling below. I m hoping your supply lines are not running through there as well. Freezing is a particular problem when pipes run.
This solution will agitate frost build up and slowly start to clear your frozen shower drain. Blot out liquid water once in awhile with paper towels.