What Type of Sealant Is Used to Seal a Drain to a Fiberglass Shower Base?

Plumber’s Putty

• Plumber’s putty comes in an airtight container of varying sizes. The putty has a consistency similar to clay when you first remove it from the container, allowing you to shape the putty into a variety of forms. To seal a shower drain to the pan, you need to roll the putty between the palms of your hands to make a rope out of it. You then wrap the rope around the drain opening in the pan and break off any part of the rope that overlaps so there is an even amount of putty all around the opening. As you tighten the drain body into the drainpipe below the pan, some of the putty might squish out, but you can wipe it away. The putty hardens as it sits in the open air, creating a hard seal.

Silicone Caulk

• Silicone caulk comes in a tube, some of which may require a caulk gun for applying the caulk. Silicone caulk is clear and has a consistency similar to pudding when it first comes out of the tube. Apply an even coating of the silicone caulk to the underside of the drain body’s lip, or the part that sits against the top of the shower pan. As with the plumber’s putty, some of the caulk may squeeze out from under the drain’s lip as you tighten the drain in place, but you can wipe off the excess caulk. The caulk will also harden as it sits in the air.

Leaks

• Leaks may develop when you use either plumber’s putty or silicone caulk. If you did not apply the sealant evenly to the gap between the drain body and the shower pan, air gaps will have been created that allow water to pass through the otherwise watertight seal. Plumber’s putty may become brittle and crack over time, allowing water to pass through and leading to leaks. When the sealant has failed, you must remove the drain body, scrape away the old sealant, and apply a fresh layer of sealant before reinstalling the drain.

Drain Body Removal

• If you need to remove the shower’s drain body, you must apply enough force to the drain body to break the seal. If the seal has become brittle, you do not need to apply as much force, but you still cannot do it with your hands. If the drain body has a grid in it, you can insert the handles of a pair of pliers into the grid and place a long screwdriver between the handles. You then use the screwdriver to turn the pliers and the drain body counterclockwise. If the drain has no grid, you must insert a special device used by plumbers, called a drain key, which expands inside the drain body until it fits snugly inside. You then use a wrench with teeth in the jaws to turn the top of the drain key and the drain body counterclockwise.