Replies

1. 
   calvin | Jan 18, 2012 06:01pm | #1

   Eric

   I hope Boss Hog stops by as he's way more familiar with I-joists.  Have you checked through the literature on 'em to find out if that would be considered ok by the manufacturer?   Those things are engineered as a system, putz with one part of it and you might have a problem.

   Apart from that, you'll gain mass, but there's still  direct transfer (not uncoupled) between the top and bottom of the I joist.  You might muffle the sound, but the vibrations will still have a direct path down to the ceiling below.

   The "cant hear much" isn't exactly db specs.

   There's a sometime poster here that knows quite a bit about sound deadening.  Try a search here and see if some of the already talked about posts don't come up.

2. 
   TedWhite | Jan 19, 2012 10:31am | #2

   Please don't install that solution, as the small air cavity will create problems. You can Google "Triple Leaf" or I can send you an article on the topic.

   You mentioned soundproofing the floor, and wanting to stop sound from coming up, is that correct? I ask because it makes a difference where you put your treatments. If the offending sound is from below, you'd treat the ceiling below forst. If the offending noise is from above, then you need to treat the floor first.

   Some good info on the process here: http://www.soundproofingcompany.com/sp-solutions/soundproof-a-ceiling/

3. 
   mikeys | Jan 19, 2012 11:50am | #3

   possible resource

   I haven't done my project, but I had been looking at this site for info. I hope it helps.

   http://www.soundproofingcompany.com/

4. 
   harryv | Jan 19, 2012 02:09pm | #4

   Eric

   I don't believe you can load the I-joist web the way you have drawn.

   We've had limited succes with insulating the joist bays with rock wool and hanging the drywall on resiliet channel.

   If memory serves me, JLC had a good soundproofing article a couple years back.

   HV

5. 
   TedWhite | Jan 19, 2012 02:19pm | #5

   I'd urge anyone that's interested to look at the article in the link.

6. 
   Piffin | Jan 22, 2012 07:26pm | #6

   There are a few general principles to follow when doing sound isolation

   First, cheapest, and most efficient is to make sure you seal any protrusions and cracks with acoustic caulk.

   Second is to absorb sound waves. eavy mass will takecare of some frequencies while air pockets take care of the others.

   I do the following and do not have complaints

   I be sure all opennings are sealed

   I use strapping on the bottoms of floor framing to isolate transfer surfaces.The strapping( furring) runs perpendicular to the framing

   I spray foam tpo the bottom of the upper subfloor

   I use a doubled gyp bd for the lower ceiling for mass.

   Others go beyond these to fill the space with cellulose or foam and/or to use expensive specialized isolation membranes.

   I have stories of those being less effective than my methods