Build Beyond Code
When first dealing with a developer, we want to review goals, targeted product sales range, and general plans before they get too far along on the architect’s desk. When we discuss the concept of soundproofing with a project developer, at some point, we’re asked if a particular assembly will pass code. Does this ceiling get an IIC 50? That’s really a three part question.
- Will the building Inspector sign off on the assembly?
- Will the assembly pass an acoustic field test?
- Will the buyer feel this is soundproof enough?
The answer to #1 is easy - yes, they will sign off on that assembly. They have signed off on that exact assembly forever, and there’s a stack of new blueprints waiting to be signed off on, and they’re the same assembly.
The answer to #2 is maybe and likely no. The assembly has a good chance of failure when acoustically tested in the field.
The answer to #3 is “it depends.” If the building is targeted as a high-end condo, townhouse, hotel room, etc., then the code will not satisfy expectations.
Building Code should be thought of as an absolute minimum. Many developers market the fact that they acoustically build beyond code.
We recently had a high end condo developer contact us regarding a new build, but also asked our thoughts on a previous building where the condo buyers were complaining of sound issues. One of the buyers hired a lab to come in and field test, and demonstrated that some walls and ceilings acoustically failed. They do not meet building code when tested. Now, there are attorneys involved. It’s never been cheaper for a homeowner to get a field test.
The most common reasons for failure are flanking and installation errors. Holes for ducts, sprinklers, pipes, etc in the ceiling, or near separation walls between units are all potential flanking pathways, and will allow sound to sneak by even the most formidable partitions. Installation errors include gaps in drywall hidden by mud, unsealed electrical, jamming a waste pipe into a wall against the drywall, resilient channel use, etc.
Testing is more stringent today.
The latest ASTM field test standards are more rigorous than in the past. The current ASTM E336-20 for Airborne Sound, and ASTM E1007-21 for Impact Sound don’t allow you to stuff flanking paths to remove their liability. This means a lot more planning needs to take place to minimize flanking issues in the real world.
