Sorry if this has been addressed in the past and I haven’t found it. We are getting ready to expand our apartment into a sizable attic and are trying to be as smart as possible about building to reduce sound transfer from the new attic space to the living space below. It’s an 1890’s Edwardian house and the current ceiling joists are full dimension 2×6’s roughly spaced every 32 inches with a 17.5′ span, so we will need to add new floor joists for the attic floor. We were planning on running new engineered 11 7/8 thick floor joists between the existing joists and holding them an inch or two above the existing ceiling to eliminate mechanical contact between the two floors. How much will the air gap between the floor joists and the ceiling below affect the sound? Is an inch enough? What else can we do during the buildout to minimize sound without breaking the meager bank?
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Greetings
user-558221 wrote:
Sorry if this has been addressed in the past and I haven't found it. We are getting ready to expand our apartment into a sizable attic and are trying to be as smart as possible about building to reduce sound transfer from the new attic space to the living space below. It's an 1890's Edwardian house and the current ceiling joists are full dimension 2x6's roughly spaced every 32 inches with a 17.5' span, so we will need to add new floor joists for the attic floor. We were planning on running new engineered 11 7/8 thick floor joists between the existing joists and holding them an inch or two above the existing ceiling to eliminate mechanical contact between the two floors. How much will the air gap between the floor joists and the ceiling below affect the sound? Is an inch enough? What else can we do during the buildout to minimize sound without breaking the meager bank?
If your engineered joists size is correct for spacing @ 32"centers...
Look at laying rock wool sound batts between the existing joists on top of your existing ceiling and also study up on a layer of Homasote sound board over your thick subfloor. The mass of your subfloor necessary for the span may already be enough. Increased mass and the separation of ceiling and floor system is a good start. Carpet above I presume.