Flanking and Soundproofing Project Failure

Flanking is the primary cause of failure in soundproofing installation projects and a key focus of every design and installation project that we engage in at So Quiet Soundproofing.

Flanking Explained

Flanking transmission is a term used to describe a situation when sound passes around, over the top, or under a partition separating two spaces. This means that the sound will travel around a wall, floor, or ceiling and through a path that is less insulated than the wall or ceiling itself.

Flanking “paths” for sound transmission include ductwork, concrete slabs above or below a partition, deficiencies in insulation in a ceiling cavity, back to back outlets, and other hidden paths through walls and ceilings.

Typical Flanking Paths Can Include

  • Ceilings – Above and Through the Ceiling Space
  • Floors – Through Floor and Floor Joist Space
  • Through Windows
  • Fixtures & Outlets – Light Switches, Telephone Outlets, and Recessed Lighting Fixtures
  • Shared Structural Building Components – Floor Boards, Floor Joists, Continuous Drywall Partitions, Continuous Concrete Floors, and Cement Block Walls
  • Structural Joints – Perimeter Joints at Wall & Floor, Through Wall & Ceiling Junctures
  • Plumbing Chases – Junctures Between the Walls & Floor Slab Above or at the Exterior Wall Juncture
  • Around the End of the Partition Through the Adjacent Wall

Soundproofing and Flanking


Why Flanking Causes Soundproofing Project Failure

In both new construction and retrofit soundproofing, simply installing a high performance wall or ceiling between adjacent spaces is no guarantee that the soundproofing will work and create privacy and quiet in a room.

Much like water, sound will easily find the path of least resistance from one space to another. Unlike water, sound does not travel in a linear direction, but instead it reflects off of all the surfaces around us, and therefore it can travel through complex paths very easily to make it’s way into a space.

When working on your soundproofing project, it is risky to assume that just because the contractor or architect has specified high performance walls, windows and floor/ceiling assemblies that the installation will deliver the results that you expected.

Ultimately soundproofing in your home may depend on the tradesperson installing the materials on the job who, for all his pride in the quality of his workmanship, may know little or nothing about fundamental noise control techniques unless he is give the right supervision and direction.

There is no easy or inexpensive fix for soundproofing flanking paths. Close inspection of the site conditions and construction of walls, ceiling, and floor structures during the project can save a great deal of heartache and expense later on.

Whether soundproofing is accomplished during new construction or is retrofitted during a renovation, So Quiet Soundproofing has the products and the technical experience to help identify and solve your noise and privacy problem.