How to Dampen Sound in Drain Pipes

Find the length of the drain pipe that you wish to soundproof. For multiple pipes, keep track of the measurements separately.

Measure the outside diameter of each drain pipe you wish to sound insulate. Pipe diameter is particularly important with closed-cell foam pipe insulation, which looks like a long foam tube and must fit the pipe snugly. While you can modify it to narrow more, it's easier to buy the right size instead.

Wash each drain pipe with hot, soapy water and a clean cloth. Dry with another cloth and wait for all moisture to evaporate before proceeding. This is especially important with pipe wraps (in contrast to molded pipe foams) that are self-adhering or those which must be glued to the pipe. Insulating pipe wraps that are taped to the pipe on the outside are not affected by dirt and oils, however.

Cut the pipe soundproofing material to the size needed, as applicable. Typically, sharp scissors or a utility knife are the recommended cutting instruments. Consult the manufacturer's specific instructions: Foam pipe soundproofing insulation usually needs to be cut to length and then slit up the side lengthwise to allow installation. Wraps, on the other hand, may need to overlap on the sides, in addition to cutting the material to length.

Peel the backing from peel-and-stick soundproofing wrap to prepare it for the pipe. Alternatively, spread the recommended adhesive product -- called pipe insulation adhesive and designed to use with foam -- around the pipe in a thin, even layer, or skip this step if the product instructions call for taping the insulation in place instead.

Fit foam insulation around the pipe and press it in place to seal to the adhesive, if used. For wrap installation, form the material to the pipe and press it to the pipe as you work to ensure it adheres properly. Continue down the length of the pipe, installing similarly. Overlap material on the sides or ends only as directed by the product manufacturer.

Circle the pipe circumference with duct tape or the recommended tape product if the insulation is meant to be taped in place. Follow directions precisely for best results.

Seal seams, if directed, by coating the exposed edges with additional adhesive and pressing the raw edges together. Hold until the insulation stays without support.