How to replace a shower drain from the top
If you have a leaky shower drain and don’t want to cut open a finished ceiling to get at it from below, consider using a special drain such as the WingTite Drain, which can be installed from above if the drain is in a plastic or fiberglass shower base. This drain has an O-ring that seals to a typical 2-in.ABS or PVC drainpipe (adapters are available for 1-1/2-in. and 2-in. copper pipe). Four “wings” flip out under the shower base to clamp the drain in place. The job takes about 30 minutes and doesn’t require any special plumbing tools.
The toughest part is removing the old drain flange. You’ll probably have to cut it with a hacksaw blade and pry it loose in sections from the shower pan. Leave the existing drainpipe intact. The WingTite Drain simply slips over the drainpipe and an O-ring seals it. apply 100 percent silicone sealant to underside of the drain flange to seal to the shower base. A stainless cover fits over the top (although decorator finishes are also available).