Help! My wife and I just bought a log home in Maine which we love but we have a problem. The 4×8 joists are decked with 2 inch v-groove decking that is both the finished floor upstairs and the finished ceiling downstairs. It looks great and the workmanship is above average. The problem: the decking provides almost no sound insulation. We would like to sound insulate between the master bedroom upstairs and a guest room downstairs. We don’t want to carpet upstairs and I don’t think that would take care of it anyway. One thought was to screw a couple of layers of homasote (still available??) in the bays between the joists (24″ on center) and then probably a finish layer of v-groove pine over that, still leaving some of the joist exposed. I’m wondering if a gap would be better (is air a better sound insulator?) between the homasote and finished ceiling? Anybody have a better method? I’m all ears!!
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You're headed in the right direction, but the sound deadening board really must be on the floor above to be most effective. Otherwise you still have a sound "short-circuit" between the source of noise (footsteps mostly) and your ears downstairs, through the joists themselves.
Carpet is the most effective first step in providing an increase in the IIC (impact isolation class) of a floor-ceiling system, but if you can't tolerate carpet, a homasote like product used as an underlayment for wood flooring is often used in the multi-family arena. Adhesive attachment is the way to go, providing a floating walking surface uninterrupted by nails.
My last suggestion is similar to what you describe, but instead of sound deading board, attach the ceiling boards to resilient channels designed to reduce structure borne sound. They act like vibration isolators and are often used in commercial construction. Just be careful not to screw through the channels into the floor above or you defeat their effectiveness.
Bruce A. Maser, AIA
Bruce:
Thanks for replying. If I understand correctly, you are saying that carpeting with a standard pad would provide the best bang for my proverbial buck, followed by the idea of homasote in the bays with a finished ceiling over the resilient channel. Am I following you?
We hate to cover what we think is a beautiful floor with carpet but it's sounding like the most effective method and would be less labor intensive. Thoughts?
Tim
Tim, my comment on the homasote was directed toward an application beneath wood flooring on the second floor. This way you separate the walking surface from the structure and still have the wood floor, albeit a new one. It's an expensive project involving undercut doors and raising baseboard, but if you love wood floors....
The resilient channels would normally go on without homasote, and although I've never seen it done, if they were installed over the homasote, it should be more absorbent. Still you have the problem of sound transmission through the joists, but you'd probably cut it in half. Again, carpet with or without pad is most effective.
Bruce
an area rug would gain you a lot of impact sound reduction for little cost (relative to laying an entire new floor upstairs, as described above) and would still allow much of the wood floor to be visible,
at least, that's what they did in the old days!
of course, with an area rug you won't have the padding underneath, and you'll still have open areas where foot falls will make the impact noise...
If your problem is foot sound, these approaches will all help. If you also have voice, TV and other noise problems too then the second ceiling down stairs, between the beams with insulation and 'z' channels for de-coupling will help them too. All depends on what you want to achieve, and all come with pros/cons.
Z channels? I am trying to insulate for sound on a shared wall of a duplex. The wall has a stair well on both sides and there is not a lot of room for putting some kind of insulation in because if the the stairwells get smaller, getting furniture up and down would be even harder. Any ideas? I need explanations that a non contractor, non builder can understand. I don't know what a z channel is and where you buy it--or do you tune into it? Thanks
If you do anything that increases the floor thickness, remember to figure on rebuilding the stairs or that first big step will kill you. More people die of accidents in their homes and the stair is the leading source of falls.
Are you trying to keep the people in the guest room from hearing you in the master, or the other way around?
To keep them from hearing you walk, or if you have a TV on a table up there, put something on top of the floor. You can just try it and see how it works. Put a bunch of towels on the floor and have somebody go upstairs and tromp around and stay underneath and see how much difference it makes.
As to your question about air being an insulator for sound, well, yes and no. At least it's an impedance mismatch. To put it in layman's language, sound loves to travel through solid objects. You know the story of the train robber putting his ear to the steel rail to see if a train is coming? You ever been underwater when a motor boat went by? Two tin cans and a tight string? So if you disconnect the solid object from the thing making the noise, the sound doesn't get such a good connection to go through it. If you put an anti-fatigue mat under the table with your TV on it, I bet it will get WAY quieter in the room downstairs. Put down carpet runners just where you walk.
However, if you are hearing people downstairs in the guest room, you might have to consider even more carpet. You can test it by piling quilts and stuff around so you feel comfortable that it will do what you want before you commit. If it just doesn't work, then you can try treating the room and ceiling below. You can start by just decorating the room itself with more fluffy stuff. The less sound that's reflected off the walls and floor is less sound that's going to transmit through the ceiling. Put carpet down there if you want to be the ones to enjoy the wood floor the most. Hang quilts on the walls. Put an upholstered chair in there. Pile that bed up with pillows. If that STILL doesn't do enough, go for the ceiling.
Again, I would experiment before I started nailing stuff. You can get R-11 fiberglass sound proofing insulation and just push it up there and see if it helps. Then go to the trouble to make a new false ceiling once you know it's worth the effort. I don't have any numbers on homosote versus fiberglass. I would just try the easiest least expensive way first.
Good luck!
B
That's sound advice (pun intended). Cheap experimentation makes cents (sorry) before you nail anything down. Okay, okay I quit.
bam
Bruce and BReece:
Thank you. Sound seems to travel nicely both ways. Last time we had guests (just moved in at the end of February) we relived the Waltons' schtick: "g'night John Boy, g'night emma...." etc. with our guests below us. One big culprit is our chocolate lab's toe nails clicking on the floor (Yeah, I know......trim her nails!!).
We put down a large rug in one area this past weekend and sound transmission definitely went down. I think we are leaning toward carpeting upstairs and then will see what happens. I really don't want to do anything to the bays downstairs but will cross that bridge if need be. Anybody: are all carpet pads created equal or will one have better sound-deadening qualities than others? Last question for now: where to get resilient channel if I need it and how to install it?? Thanks for your time on this subject. First time online here for me although I've been reading FHB for quite a few years. Nice to have this forum...Can't seem to come up with any good puns like Bruce 'tho!!!
Tim