Unlike your kitchen sink, which usually drops straight down into a heated crawlspace or cabinet, a bathtub drain runs horizontally for a few feet before connecting to the vertical stack. Often, this horizontal run is located just a few inches below the floor—or worse, inside an uninsulated exterior wall or a poorly sealed subfloor.
There is nothing quite as jarring as stepping into a lukewarm shower on a freezing January morning, only to look down and realize the water is rising around your ankles. bathtub drain freezing
When the wind chill drops below 20°F (-6°C), cold air seeps through foundation vents, missing insulation, or cracks in the siding. That cold air hits the cast iron or PVC pipe. Add a little bit of standing water left behind after your shower, and you have a recipe for a solid ice plug. Here is the gross truth that plumbers know but rarely advertise: Bathtub drains freeze faster than other drains because of soap scum and hair . Unlike your kitchen sink, which usually drops straight