Need to reach a certain IIC rating? Read this before you contact an acoustic consultant.
This is something that comes up every day in my line of work: IIC [and STC] ratings of floor-ceiling assemblies. I get calls from homeowners, architects, contractors, developers, product distributors- pretty much anyone involved in flooring whether they’re on the design side, sales side, or construction side. Almost always, it goes the same way: Customer: I need to reach IIC — (usually it’s a 50 to reach code minimum, but sometimes it’s a 60). Which underlayment should I use? This is where I try my hardest not to sound disinterested or condescending, because I really don’t feel that way- it just requires a conscious effort not to sound robotic when you’ve gotten used to asking the same questions. Chances are, other acoustic consultants may have a similar experience, so here’s some sound advice to prepare yourself with before you contact an acoustic consultant. IIC and STC ratings are dependent on entire assemblies, not any single element. This means that you’ll need to have all of the details of your floor-ceiling assembly before you can expect real advice from an acoustician. Ideally you’ll have an architectural drawing calling out each element and it’s thickness in the assembly, but if not, I usually email a list like this for them to fill out: – Floor Finish – Underlayment – Subfloor system (concrete slab? wood joist? truss? spacings, thicknesses, gauges, etc.) – Batt insulation in the ceiling cavity? – Resilient channels? – Ceiling details (material, number of layers, thicknesses?) The science of predicting (more…)