*
I want to sound proof my basement ceiling. There is no carpet on the floor above it is very noisy in the basement as a result.I have full access to the joists. I’m would like to cut the noise down alot with out having to carpet the floor above. Any suggestions would be great
Discussion Forum
Discussion Forum
Up Next
Video Shorts
Featured Story
Fine Homebuilding's editorial director has some fun news to share.
Highlights
"I have learned so much thanks to the searchable articles on the FHB website. I can confidently say that I expect to be a life-long subscriber." - M.K.
Replies
*
Let tell you insulation won't do it alone, or really even make much difference. I did a basement like this and insulated and found it very unsatisfying. I don't have proof but I think isolating the drywall from the joists would greatly help. I'm thinking of 1/2" foam board or celotex. I base this on the thought that if drywall is directly attached to the joists they will transfer the noise to the ceiling.
Anyway, that's my theory and I'm sticking to it.
*I second what J.D. said. You need to isolate each layer of material. I have used 1/4" T foam board between the joists and the drywall. Even better is to fur out the drywall from the foam board. This creates a layer of dead air that further reduces sound transmission.
*
There are a number of things you can do. For insulation between the joists use "rockwool" - which is an actual acoustical insulation. We've used it in a number of sound proofing projects. Works fine.
Another quick trick is to use clips to decouple the basement ceiling drywall from the joists - which transmit noise.
I'd do both. A good construction manual should discuss soundproofing options.
*
You're going to have a hard time getting rid of all the footfall noise on the wood floor. Starting from the begining you could have constructed a "floating" floor and isolated it there. Now, the ideas the guys above offer are your best course. Some dense mineral fiber - fibreglass or rockwool - and I'm not sure you can get the dense fibreglass any longer - will help with somenoise. Airseal both planes - all the holes and annular rings around penetrations of teh floor and ceiling below. Gaskets on doors between the areas also. Then drywall on resilient channels - USG's RC1'a or similar. A double layer of drywall - laminated together with jointcompound and a notched trowel - would be noticable better than a single layer. Edges and penetrations should be sealed - with a resilient, non-hardening, caulk. (USG markets an acoustical caulk like this.) Hopefully an unbroken ceiling plane with the edge supported with a angle - liek is used for hung ceilings - with caulk.
These kind of efforts suffer from the weakest link - one unsealed hole will negate much of the effort of all the ones sealed, and so on. On the otherhand, it can be done - I see (hear?) it on a lot of the projects I design In your case, I wouldn't expect much better than an stc in the low 50's given what you describe - but I think you would find that pleasing.
Good luck
*
Speaking as an architect and ex-homebuilder who has recently hired acoustical engineers for projects, I would say YES Bill you hit a lot of things on the head (quietly I guess). Acoustic batt insulation is excellent and the idea is to fill the air cavity. A dead air cavity unfilled is NOT good. That works for thermal insulation , not sound. An STC rating of 50 is actually quite good (shooting for 55 to 65 is even better, but this is not an exact science)! If your joists are exposed, you should then strap with resilient channels (also called Z-channels) then hand 1/2" or 5/8" GWB. Adding an extra layer of GWB on a ceiling is A: a bitch to do, and B: will give you more mileage on walls than a ceiling; C: it adds weight to the system which, over time, stresses connections. If you want to go further than the described system, I would add 1/2" sound board directly to the joists (it's a dark homeasote type product that's cheap) then strap them and add GWB. Another variation is to strap the joists with 3/4" wood, then add resilient channels. The overall depth of the system has a big impact on sound attenuation, up to a certain size where it becomes superfluous. Another example, a classic problem is deadening sound in an old building that has lath & plaster ceilings. You are best to blow in insulation (such as cellulose) to fill the cavity, add 3/4" strapping, then resilient channels and GWB directly over the lath & plaster. Of course, sealing all holes is gona help a lot, but if the cavity is filled well, this is less of an issue. When you're all done, do the Dance-the-jig test upstairs, or, my favorite, the "scream test".
*
Gary - I agree the double drywall is not easy but the resilient channels work better if fully loaded and -in the end - all we're trying to do is make up for lack of mass - so adding some here usually benefits.
As far as strapping the resilient channels over a solid surface - I haven't personally seen these lab reports, but all the acoustical consultants I have worked with say this is not as good as having the wall cavaity behind. The air space behind the resiliently mounted membrane helps a lot in dampening lower frequencies.
And STC 50 is good - but footfall noise is tough to beat and 50 is not sound"proof".
*Rich OWell, I just did what you want to do. Even posted messages here and got feedback from some of the same people. I used R-13 fiberglass in the ceiling (2X10's) although I was advised later that R-11 provided the same degree of "deadening". I used resilient channel on 16" centers. I was troubled by the tendency of the channel to pull away from the joists (flex) under the load of the drywall so I doubled them (overlapped them--one side is open, the other is screwed to your surface). Some resilient channel has slots that are to be aligned with joists (this channel all goes up perpendicular to the joists)--my channel was evenly perforated so it didn't require aligning. I caulked all the edges and seams prior to taping--I also caulked around the ceiling light box and the smoke detector box (don't forget that most places require a hardwired smoke detector in bedrooms/basements). The sound transmission IS reduced BUT when a kid drops a toy on the vinyl floor upstairs (its a kitchen) it seems loud. If doing it again, I think I would insulate, try some sort of soft sound board (buffalo board?) directly over the joists, then the resilient channel(but not overlapped, maybe 8" OC--use fine thread screws that only penetrate the channel), then the drywall. I probably would go for 5/8" instead of 1/2" as it is supposed to be denser but the two layers of 1/2" Bill Conner mentioned would probably be better. It is surprising how much difference the caulking makes. My client had a forced air furnace and the ducting path was not all that long between the two rooms but I was paying more attention to footfall/toy drop noise. The difference in the sound of a voice being transmitted has been far more dramatically reduced. Bill Conner advised me to check out usg.com for addition info and it was helpful. Best of luck. Thor
*
So well, it seems we're just about all in agreement. The best approach is to insulate, add sound board, strap with channels, add GWB. Caulking and sealing is very important too. I'd like to add that it is incorrect to say that "all we're trying to do is
*(oops I got interrupted) "make up for lack of mass". Mass alone does not control sound. Sound control, even more than thermal control, is based on the Whole Assembly. It is also very nuanced due to the ways sound travels. Resilient channels are very very helpful as would be building with metal studs because they take a solid wall and let it bounce as it's vibrated by the noise. There's a lot more to say, but also keep in mind that it is relatively easy to get voices and high sounds deadened, it's harder to kill footfalls and low sounds. Finally, if you try to go much further than the group of us has described, you pretty much have to consider building a separate framing system to support your ceiling below (otherwise known as a double-floor system) It's do-able but then, what the hell, you can hear voices out on the street as well as car alarms and birds. How quiet do you really want to be???
*
You're right. I should have said that all I'm trying to do when projects I work on resort to these techniques is make up for lack of mass. A masonry wall or thick floor slab will make it a lot easier to attenuate the sound energy - especially across the wide range of frequencies in music for instance - than light weight stud and joist framing will ever do. Not to mention its more likely to air seal between the two. So I'm not trying to make this light weight stuff act massive - only using these techniques because mass was not an alternative.
But I really should have started with separation as being the fundemental - more distance and more air between source and listener - is much easier and less expensive to get sound attenuation. All these fussy details of light weight stuff depends on near perfection.
By the way, no one has mentioned connecting ducts and back to back electrical boxes, etc., as weak points to be avoided. Also shorts like rigid conduit or piping should be either rerouted or isolated with flexible connections.
*Simply stated. use batt insulation in basement ceiling betweeen joists.Pete Draganic
*
Far too simply stated. Haven't you been reading what we've all said? If you do that you get just a tad better than a cheap motel room wall. From STC 25 or 28 up to STC 30 or 35. That's still pretty poor. Add the channels and you get a jump of over 10 STC values, up to 45 or more. Anyhow . . .
*
Okay, okay,,,,but, heaven forbid, you want the look of exposed beams? What the options then? Is there any wisdom to adding that homeasote product directly to the underside of the sheathing (between joists, that is)? Or maybe, atop the joists and below the floor sheathing...this doesn't sound like it would work well considering the construction adhesive that is so important to proper floor installations? Anyone.
*If you can put it on top of the joists, go back to the early posts. The best way to get this isolation is a floating floor system. Sheath the floor - put in isolation - and put a second floor in. There are a variety of ways to float the floor - most involve some sort of resilient pad or matt. I believe that was not an option in this problem - the finished floor above was in.Adding a layer of homasote between subflooring and finished flooring may - should - help - but I have never seen laboratory test data on that - only manufacture's claims.If you're now asking about timberfarme and plank construction - with no joist cavity what-so-ever - I'd say that attenuating the noise will be difficult. Sort of a poor design choice if noise separation was a priority. I had an office in the old Marlin rifle factory that was built that way. When I shut down the radio, computer, lights, etc. and listened, I could clearly hear the people above walking - knew almost exactly where they were at any given moment.
*I have seen sheet (roll) lead that was sold as a sound deadner. My guess is that it adds to the mass. I think it was for laying on the sub-floor. I doubt it would be easy to lay on a ceiling!Frank
*Frank - often referred to as leaded vinyl - basically same stuff in the aprons, etc., they use during an x-ray. Lots of mas in a thin package. Particularly appropiate for retrofitting industrial applications - like where it's got to be move from time to time. Pounds per dollar, hard to beat drywall.
*
To continue to add to this endless topic; I recently added a washer/dryer to my upstairs apartment by building into the knee wall a laundry alcove. I put soundboard and two layers of 3/4" particleboard down as a somewhat resilient and very massive flooring. I then added sheet vinyl. It IS quite quiet though I think strapping it perpendicular to the joists and then one layer of 3/4" as a subfloor would've been equally good. And finally, let me ask a question to you all: I am considering putting in a basement studio apartment. I would sound isolate the floor as we have all discussed but the hardwood flooring above is often running parallel to the old plank subfloor. If water is spilled anywhere it flows right down into the basement! How do I deal with this??? If I try to put polyethylene up first to catch the water and hold it until it evaporates, I am sure to still get leaks cause staples and lap joints will not create a perfect seal. What to do, what to do?????
*I hate to sound stupid, but does someone have a product to isolate the subfloor from the finish floor, such as a thin rubber mat? What is the brand name and where do you buy it?Thanks to all who respond to keep the rest of us informed.
*
I want to sound proof my basement ceiling. There is no carpet on the floor above it is very noisy in the basement as a result.I have full access to the joists. I'm would like to cut the noise down alot with out having to carpet the floor above. Any suggestions would be great
*
Tom - what type of isolation are you looking for or what are you looking for it to do? Moisture, movement, acoustical, vibration?