Replies

1. GBA Editor
   Martin Holladay | Mar 13, 2014 09:46am | #1

   Andre,
   This question comes up frequently here at GBA. You might want to read these threads on the topic:

   Noise Reduction retrofit - which insulation to blow in between floors?

   What is the best way to soundproof a home between 1st and 2nd floor?

   Sound insulation for a city apartment ceiling?

   Is there such a thing as eco-friendly soundproofing?

   Soundproofing Bedrooms

   Has anyone tried Roxul Safe N Sound (or similar) for soundproofing?

   How to Keep the Noise Down

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2. 
   fitchplate | Mar 13, 2014 11:17am | #2

   It all depends on …

   … your stage of work? Presumably you're asking about a wood-framed structure? Are the framing and drywall completed yet?

   … location and accessibility … are your joists' cavities open underneath?

   Sound transmission features … Do you have ducting or other mechanical in the floors? If so what type?

   What kinds or types of sound are you wanting to stop (walking, music, talking, kids playing, mechanical equipment, kitchen and bath noises; etc)? Do you want to stop sound from goint up or down? It makes a difference to the solution.

   There are basically 2 ways to sound proof: (1) dampen the sound (absorb) and (2) disconnect from the source of the sound (decouple). There is a market trying to sell you sound proofing technology for mass loading and decoupling; it's very expensive. You can find all kinds of product on the web.

   But there are lower cost construction techniques and materials as well.

   You need to supply more info.

3. 
   vernacubuild | Mar 13, 2014 05:46pm | #3

   Thanks Martin. Fitch, framing is complete, but electrical and mechanical have not started, only plumbing. Will be using ductless. Want to minimize sound of kids walking playing upstairs.

4. 
   fitchplate | Mar 14, 2014 09:43am | #4

   These are details of true affection for a building; not to be expected from contractors and low wage employees. Only you will know and only you will appreciate the benefits. I assure you, these will make dramatic improvements in sound control and also building performance.

   Stop sound transmission through stopping vibration.

   Roxul Safe Sound, cellulose or chopped glass will help a lot. But you need to break the vibration pathway between the floors (i.e. fill the airspace) so the installation should be either dense packed or tight friction fit; filling cavity top to bottom, end to end, side to side.

   If you have not drywalled the ceiling below yet, the heavier the drywall the better; one or even two sheets of 5/8”. It needs to be glued and screwed. Best to have (caulked not foamed) minimal ceiling penetrations (ie, light cans, octagon boxes, etc) and where possible to surface mount or avoid fixtures on/mechanical in ceilings altogether.

   If you have erected partitions already, the plates on up and down floors should be edge caulked (flexible long life caulk, no latex caulks, polyethers are great for this – see BestMaterial.com) with full length caulk runs along plate bottom edge to floor, to reduce bounce, vibration transfer. Careful not to interfere with drywall installation. If you haven’t erected the interior partitions yet, use a dense, double thickness foam sill air sealing gasket on top plates of downstairs partitions, and under the upstairs partitions.

   Where possible, caulk the back of all drywall/stud joints and tape all drywall-to-drywall butt joints. Do it along each stud and plate. Of course you can only do one side of each wall so choose wisely.

   It will help also to use insulation in all abutting vertical partitions, not just the floor, and to glue/screw drywall there as well. Use high quality drywall glue, low shrink characteristics; not Liquid Nails or other low retail quality products. Look at commercial/professional Tightbond products. If you can accept it, don’t use water based adhesives for this job.

   Wood shrinks, nails slide and pull, drywall glues shrink, drywall also expands and contracts. Proper installation and construction materials are critical to low sound transmission.

   Screw all subflooring into the joists/wood I’s and glue. Keep ducts out of joist bays and use soft (fabric) anchors for any piping. Polyurethane geotechnical fabrics are good for this as gaskets for all wood to wood and other material sound dampening connections.

   Finally, use a flooring that required underlay and buy the best sound dampening floor underlay available (beware of hyperbolic advertising). Get a demonstration and product comparisons from your supplier to prove the quality/effectiveness of the underlay for sound dampening purposes. Of course vinyl and laminate flooring as well as asphalt based flooring are the best for sound dampening (i.e. due to density and mass).