attenuation capabilities in above ground in - stallations . Simply put – there is no piping sys - tem that is quieter than cast iron . No one wants to hear the gurgling and sloshing sounds of water from fixtures on floors above flowing down the walls, especially in high - rise condominiums, commercial office buildings or high - end hotels . Using cast iron for waste piping will result in a plumbing sys - tem that is twice as quiet compared to an all - plastic system .   Density is the primary factor in the sound - dampening quality of cast iron . Cast iron is sig - nificantly more dense than plastic . But density isn’t cast iron’s only advantage when it comes to noise . The method of joining sections of pipe together also plays a key role . The neoprene gaskets used in cast - iron installations keep each section of pipe from touching, thus eliminating any contact - related sound . Plastic systems are solvent cemented into rigid systems that can cre - ate noise as they expand and contract with heating and cooling . Some “fixes” that plumbers attempt to solve plastics’ noise problems may not actu - ally fix the problem . Wrapping plastic pipe in insulation to muffle the sound of water cas - cading through the pipe means additional time and materials . Cast - iron plumbing systems have been in use for centuries . Cast iron is reliable, du - rable and easy for a skilled tradesman to in - stall . All too often we have seen piping sys - tems value engineered to plastics because of the upfront costs associated with cast iron . But, as you can see, the added steps and considerations involved in installing plastic can actually add technical complexity, cost and liability to a project, thus eliminating any upfront savings in material costs . In our business, we see the negative con - sequences and large liabilities created by value engineering and poor craftsmanship . In my own condominium in Charlotte, the un - derground PVC waste line to the city service failed due to deflection and had to be ripped out after raw sewage backed up and flooded the ground - floor units . The line was replaced with service cast iron and is functioning fine . Instead of always racing to the bottom, perhaps it’s time we step back and start us - ing the correct materials for the installation – not ones that can create unintended mishaps down the road . Roddey Dowd, Jr . is president of Charlotte Pipe and Foundry Com - pany, a 108 - year - old manufacturer of cast - iron and plastic pipe and fitting systems headquartered in Charlotte, N . C . guest editoria l 1 . 800 . 438 . 6091 / www . charlottepipe . com Don’t rede ne the engineer assessment .   Remember, they’re called speci cations for a reason . When an engineer speci es cast iron pipe for a speci c job, it’s because they believe it’s the right material needed to get the job done correctly and e ciently . Engineers know that using cast iron instead of plastic for speci c jobs eliminates costly extra steps for things like re - stopping, noise reduction and thermal expansion . And they know that even after the extra steps are taken to make plastic comparable to cast iron, plastic is still outperformed because it’s just the wrong material for the job . Simply put, there’s a time for plastic and a time for cast iron . The time for cast iron being when the engineer speci es it . Because if you think about it, they don’t call them speci cations for nothing . Suggestifications [suh g - jest - uh - fi - kay - shuns] : n . vague descriptions or loose assessments of what a job may or may not need . The engineer suggestifications stated cast iron pipe so they chose plastic .