The first place I considered is windows. I researched quite a bit on this forum regarding soundproofing windows and it’s been very informative! I have learned that double pane windows are just as effective (and usually less expensive) as triple pane windows as long as there is sufficient spacing between panes and at least one pane is thick laminated glass. But shouldn’t one consider that you may be spending too much money over-engineering your window because sound could be penetrating walls and ceilings too? No sense having a 50 STC rated window if your walls are only rated to 45 STC, correct?

I did some research online regarding STC and it’s been mostly inconclusive. Is anyone aware of a website that offers STC ratings on different types of construction? For example, what would the STC rating on a 2 x 4 wall with insulation and stucco be? Or how about a 2 x 6 wall with insulation and cement board siding? Or the same wall without insulation? And perhaps that same wall with 5/8" rock or maybe two layers of ½" rock? OK, a that would be a bit pie in the sky to have a site that broke all those numbers down but anything would be better than what I’ve found.

I’m currently leaning towards going with this construction method for all exterior walls:

--2 x 6 walls using wood studs
--Standard R-13 insulation batts tighly packed into the wall cavities
--cement board siding on exterior
--two sheets of ½" standard drywall on interior

Another option is:

--2 x 6 walls using wood studs
--icylene blown in insulation
--stucco exterior
--one sheet of 5/8" standard drywall

The sound insulation qualities of icylene (or other blown in insulation) is questionable. I have read that this type of insulation along with standard fiberglass batts provide little to no reduction in lower frequency sounds (e.g. auto traffic). I’m not even sure if it provides any sound insulation qualities as some sites have suggested but I would assume that there must be some buffering in the high frequency ranges.

The icylene option is considerably more expensive than standard batts. Would it be worth the upgrade or would there be no improvement? I realize one benefit of icylene is that it helps fill all those gaps and crevices at outlets and switches. But I assume that I could remedy this with a lot of caulking in those areas.

I have been told by my contractor that going with a stucco exterior will help reduce noise. Assuming that there is more material (1/2" plywood + 1/2" DensGlass + base coat + stucco VS. single panel of specified cement board siding) the stucco option should reduce noise transfer into the home. But does anyone know how much? Would it be better to just go with two layers of ½" rock vs one layer of 5/8" rock on the interior?

I’ve read that going with two layers of ½" rock and GreenGlue in between can replicate the STC rating of very expensive QuietRock drywall. Can anyone confirm this? Would two layers of 5/8" just be overkill?

Also, I will have a neighbor in my duplex (which I plan to rent – not sell) and I don’t want to hear them nor do I want them to hear me. I plan to go with a 2 x 6 wall, R13 insulation batts and two layers of ½" drywall (Green Glue between sheets) on BOTH sides (total four layers of ½" drywall). Will this create a very good STC? Enough so my neighbor can’t hear my loud home theater system? Do I need to stagger studs to really bring the noise down? Keep in mind that floor area is at a premium here – the city only allows me to build so much interior space for my lot, including the walls. So I have to be very careful about how thick my walls are. Basically, I’m looking for the best STC rating with the smallest wall footprint. This actually holds true for exterior walls as well because the city counts exterior wall footprints as floor area also (which I think is ridiculous because this stifles energy efficient design which usually includes thicker, well insulated walls).

I’ve been obsessing over this way too much but I’d hate to build this house and be unhappy with the freeway noise after I move in. I’m afraid I’ll either go way overboard on soundproofing my home and blow my budget OR not do enough and be stuck living in a noisy home for a long time. For all of you that made it this far into my post, thank you!!!

You certainly seem to be well aware of all your options.

I have used Quiet Rock 530 for interior sound deadening. Compared to the alternatives of double walls and resilient channel--which don't work all that well, I can confirm-- it's not much more expensive. For reducing the noise between the units, in addition to the measures mentioned, consider Quiet Wood subflooring and solid doors minimally undercut.

I've been in homes built near a six-lane artery and required to have special window units. Not only did they have triple panes, they had tight-fitting closing mechanisms. I was very impressed with the quieting job they did. So it can be done.

Good luck!

You may want to check out this link as it has some pretty good explanations.

http://www.soundproofing101.com/

worthy - I knew someone would post that! I actually live right next to the freeway right now and I love it. However, I am in an all concrete building and I only have one very small window in my bedroom and I have a second window over that window so I can't hear anything. My neighbor upstairs bothers me much more than the freeway.

Land is very scarce in Hawaii and land in downtown (where my lot is) is almost non existent. In fact there is only one lot for sale in all of town right now asking $180 sq ft. The freeway in Honolulu (the stretch in front of my land) is nothing like those in the mainland. The speed limit is a well-enforced 50 mph (lower speeds = lower wind and tire noise) and very few 18 wheelers traverse the portion of freeway I am fronting. Since this is not an interstate highway (we live on a little rock), virtually no big trucks travel at night. And I’m on the upslope of the freeway (and upwind) so I don’t receive that much fallout from auto exhaust. The other side can get pretty bad. But I didn’t want to make it sound like the freeway isn’t that bad - I need good soundproofing advice!

So you’re suggesting that I don’t go with two layers of ½" drywall and GreenGlue on each side? Isn’t QuietRock 530 over $100 for a 4 x 8’ sheet? And would this be more effective (noise reduction) than the aforementioned? I’ve real elsewhere that two sheets of ½" with GG is better than 5/8" QuietRock.

They quoted me on a standard egress window – 30 x 42" casement window (which I assume is the best window style for sound insulation).

Milgard Classic Vinyl series 30 x 42" casement window…

--no STC rating
--Vinyl frame
--Stainless hardware
--"Hideaway" handle
--7/32" laminated glass (exterior) + airspace (unknown) + ¼" clear glass

Price - $473.00

The same dimension window from Milgard Quietline series…

--40 STC rating
-- same as above but with 1/8 + airspace (unknown) + 1/8 + airspace (unknown) + 1/8

Price – $739.00

Milgard Quietline also has another window with a higher STC rating…

--45 STC rating
-- same as above but with 1/8 + airspace (unknown) + 7/32 laminated + airspace (unknown) + 7/32 laminated

Price – $878.00

I’m thinking that two panes of glass which equal nearly ½" of glass (one pane being laminated) would serve better in blocking out lower frequency noise than three 1/8" panes of plate glass (not laminated)? Could the construction of the mechanism, seal and frame help mitigate noise that it justifies the 55% price premium? The second window seems beefier with TWO 7/32" laminated panes and one 1/8 clear panes. But the price - $878!!!

I would assume that casement windows are quieter than slider windows however the Milgard product shows sliders as having a higher STC (about 1 point higher) than casement. Makes no sense to me.

Maybe I should be posting this in the windows forum?

I just checked my bills. I used QR510, which is rated at 49-68STC depending on the wall method you use. US prices as low as $39.95 per sheet. But that's the mainland!

I’ve real elsewhere that two sheets of ½" with GG is better than 5/8" QuietRock.

Green Glue's website doesn't claim anywhere near this.

Land is very scarce in Hawaii and land in downtown

(My mother inherited the land under a shopping centre on Beretannia, so I know the value! Most land is leased; hers is well into its second 99-year lease.)

Using undersized insulation serves no purpose. To begin with it will fall down. Roxul claims its Safe'nSound insulation is denser and abosrbs more sound than other fibrous insulation.

As for the price differentials--about right.

But since you're building a whole house, get prices for all your windows and exterior doors at once. Go in with plans, let the suppliers do a takeoff and get several written quotes.

The most impressively soundproofed place I stayed was at a hotel, I think in Boston, with a view of the runways. I literally could barely hear the aircraft taking off, even though there was a big window in the room directly facing the runway. Some clever techniques went into soundproofing that hotel!

Cynandjon – the site does suggest to not pack the insulation "tightly", however it doesn’t suggest leaving an airgap. Using the proper sized R19 batts as mike13 has suggested would not allow for any air space at all. Please explain how I could have an airspace but not use the proper sized insulation resulting in it falling to the floor eventually.

Sierraeast – The only "film" I’m aware of is the plastic film that is sandwiched between to plates of monolithic glass to create a laminated pane of glass. I prefer to stay away from any film product that goes on after the window is installed because I’m afraid that over time this film will degrade and bubble, fade or peel. But who knows… if there is a film out there that can be installed after the windows are in, I might use it if I’m not happy with the end result of the new construction. I really hope that I won’t have to do this though.

Chiefneil – The noise encountered being next to the freeway (this particular freeway at least) is much lower than that next to or near an airport. I’m also in Hawaii so it will be unlikely that I’ll have any luck finding a reasonably priced contractor that knows anything about soundproofing. The ones that do will likely cost an arm and a leg as they probably don’t work with residential projects very often. Because of our temperate climate, sealing a home is not something contractors here bother doing. Regarding soundproofing, I’m just going to have to hold the contractor’s hand through the entire project. I told him that soundproofing (and energy efficiency) is the single most important aspect of this project.

I did a quick google on airport soundproofing and turned up the article below, among others. A few calls might get you some details that you can apply to your own home.

flgargoyle, yes, I have looked into SIP and ICF construction. No local contractor here will touch it with a ten foot pole and if you're lucky enough to find one, they will charge you a ridiculous premium. There just isn't anyone doing it here in the islands - weather is too warm here. The other problem (bigger problem) is that this type of construction would never fly (even if contractors were open to it) in apartment zoned areas. My lot is apartment zoned and the city only allows X sq ft of building area for X sq ft lot. In other words, the interior space is at a very high premium and it's imperative that every square foot possible is used for functional floor area. The footprint of the exterior and interior walls all count towards your buildable sq footage. ICF has a HUGE footprint compared to standard 2 x 4 ext walls. All that space is gone forever and your home is that much smaller. You might be thinking what is another 15 sq ft on a 30 linear foot run of exterior wall (about what one would lose going with ICF over standard walls)? Well, consider that our average two bedroom home is 750 sq ft and you'll see what I mean. You will lose approx 55 sq ft of livable space in a 750 sq ft 2 bedroom condo. Homes in Hawaii are TINY compared to homes in the mainland. We need to eek out every little square foot possible so ICF will never work here - at least in downtown where space is huge premium. Ironically, ICF wouldn't make much sense elsewhere on the island because most any noisy area is where land is at a premium.

Because of the space premiums in your location, QR would be the preferred method of sound attenuation. One layer of QR provides STC equivalent of up to 4-5 layers of conventional drywall on resilient channel.

I received some pricing for the QuietRock product and it's very pricey.

$65.00 for the 5/8" product with 51 STC
$45.00 for the 1/2" product with 49 STC

Alternatively, I could go with two layers of 1/2" and Green Glue in between and the cost would be roughly $37 per sheet ($11 x 2 drywall + $15 GG). This would provide an STC of 53. Of course the labor would be higher.

I would argue that the two layers of standard rock would do a much better job of reducing low frequency noise because of the additional mass. STC ratings are great if you're trying to block out speech or loud voices, however, STC does not consider lower frequency noises (sub 150 Hz). You need mass (plain and simple) to block out lower frequency noise and the QuietRock product does not provide much mass. Nobody has been able to confirm my reasoning behind this but the STC doesn't help me too much if the primary goal is to block out traffic noise. I would be losing 3/8" of wall space if I go with the two layers of half inch drywall but the loss is <4 sq ft per unit. Not too bad.

Unless anyone can tell me otherwise, my conclusion is that QuietRock is not a good product to use if I'm primarily trying to block out lower frequency noise.

On its website, Green Glue claims to post a third party comparative evaluation of an unnamed constrained damping drywall product and gg and concludes: "The superior damping of Green Glue...combined with the fact that two layers of conventional drywall are heavier than one layer of thin factory damped drywall, result in the Green Glue assembly offering significantly superior performance in the critical low frequency region and superior scores in all measures of performance."

I wonder what product they used?

Standard 1/2" gypsum board weighs 1.3 lb.s per sq. ft. QR 530 5/8" weighs 2.8 lbs. per sq. ft. So in fact QR provides greater sheer mass plus several constrained damping layers.

I see that National Gypsum now has a soundproofing gypsum board with a a single damping layer; it may be cheaper to install than QR.

Green Glue claims to enable diyers to trounce the damping performance of controlled-condition manufactured products at a fraction of the cost with just a caulking gun. Amazing.

I had a designer friend who did a bank headquarters in TO. Lead sheathing it was. At least, around the boardroom. And doors that must have weighed 300 pounds each.

After some research, I've decided that metal framing was a better bet as it provided a significantly higher STC rating than wood framing. My exterior walls consist of a stucco exterior, R13 (2" thick) fiberglass insulation batts, 3 5/8" metal studs and 5/8" rock interior. I couldn't ascertain what the STC rating would be on this assembly but I'm guessing close to 50. Any advice is much appreciated!

Metal studs will also serve to protect you from the Hawaiian scourge of hosting almost every known type of termite. One downside to metal framing -- metal studs/joists lose their structural intensity much faster than wood in the event of a fire.

The following link should be able to give you a close approximation of your STC rating:

http://www.saecollege.de/reference_material/pages/STC Chart.htm

Good luck...

ronnatalie, yes, I found that cotton is a better sound insulator (and a greener product) than fiberglass batts but they are not available in my neck of the woods. And shipping it across the Pacific is definitely not an option.

When you mention stucco exterior, are you talking old-school 2" thick stucco on lathe or the more modern/common EIFS/dryvit which is installed over insulation board? I would recommend the dryvit type with 1.5" insulation board if you go with the 3 5/8" wall. the exterior insulation board will help close up cracks in the construction and increase the R-value of the wall. 6" wall construction is better if you can afford it. Always fill your stud cavity with the same sized batts. Don't put 3" insulation in 6" walls. There are three elements to good sound control. Acoustic Mass, Acoustic Seperation, and "Crack Control". The mass of your wall will help repel some sounds. A 6" concrete wall will "bounce" much more noise than a hollow 4" stud wall. Acoustic seperation deals with whether sound can propogate through a wall (or ceiling). If someone taps on the wall, does the noise come through to the other side of the wall. This is where offset stud walls, sound isolation channels or clips and similar methods come into play. Crack control is vital around doors, windows, electrical outlets, and anywhere you have a thru-penetration from outside to in. The most expensive wall can be thwarted with a cheap or poorly installed window. Call for contractors to pack voids with insulation and use foams and caulks religiously at all openings. Buy the best you can afford/justify. Oh, and no window film is going to make a window quiet. It may improve the insulation quality/reduce light transmittance, but acoustic performance will be minimal. With steel studs I would use acoustitherm or Fibrex insulation instead of fiberglass. Almost all fiberglass insulation is light-weight , even the "acoustic batts" are almost identical to standard batt insulation. Acoustitherm and Fibrex are rock/slag based products that are much denser. Request a 2.5 pcf or higher product. It will provide the same R-value for your wall and help increase the wall mass. Hope some of this is useful.

I build SCIFs that must meet sound (and electromagnetic) transmission standards.

The 'standard' wall is steel studs, fiberglass filled, with 2 layers of 5/8 drywall on each side (staggered joints by one stud bay between layers ).
Acoustic caulk on top and bottom plates.

Drop leaf door seals for the bottom and acoustic seals on top and sides.

You need to evaluate what noise frequencies you need to block.
Low frequencies may not be a severe problem.

The contractor (a very good friend of mine) convinced me to go with stick construction instead of metal because of the additional cost. I was also told that heavier gauge metal studs are no better in sound insulation than standard wood studs. Not sure if there is much truth to that.

Currently, our exterior walls will consist of 5/8" QuietRock (model 525) drywall on 2 x 4 wood studs, 1/2" plywood w/waterproof membrane (Tyvek or similar) and standard fiberglass insulation in between. Attached to the exterior plywood are 1 x 4 wood furring strips and I plan to attach 1/4" thick 4 x 8 foot HardiPanels to the wood furring strips. The HardiPanels will not be placed butt to each other but will rather have a space of approx 5/8". This is to create a "grid" pattern to the exterior wall. My goal is to build a modern, minimalist home.

So essentially, (from the outside in) I have 1/4" HardiPanel concrete board, 1/2" plywood sheet, 2 x 4 stud and 5/8" QuietRock on one wall. Would anyone have any idea what the STC rating of such an assembly would be?

I've been told by a local dealer of QuietRock that I should look into the "triple leaf" effect and that spacing the HardiPanel away from the plywood could cause the STC rating of the wall assembly to drop as a result of this phenomena. My reasoning would be that placing the 1/4" HardiPanel 3/4" away from the plywood would increase the STC rating since we are adding a third but very small airgap. Keep in mind, however, that the HardiPanel assembly is not completely sealed and air/sound tight because I am spacing each panel away from each other by roughly 5/8".

The other options I was looking at was going with 2 sheets of standard 5/8" drywall and GreenGlue between. I have heard that this assembly would reduce low frequency penetration into the home much better than one sheet of QuietRock 525. Is this true?

And another facade option would be to go with stucco so instead of a 1/4" sheet of HardiPanel and 5/8" "air space", I would have densglass, a cementitious coat and the stucco coat on top. I'm not sure if this would provide a better STC than spacing 1/4" HardiPanel away from the plywood but I'm assuming it would. If anyone can chime in on this I'd really appreciate it.

For the windows, I am looking closely at Migard's Quietline product. I may just use these windows for the bedroom windows (because of cost) and other windows in the home where people are not so sensitive to noise would likely be a standard double pane windows with thicker laminated (one pane) panes of glass (to achieve at least a 35 STC). Is this a good idea? And is it true that vinyl windows are a better sound insulator than aluminum? Everyone I talked to here says that vinyl is superior to aluminum for soundproofing but I've found some information online to the contrary. My concern with the vinyl is that it is only available in white and an off-white "tan" color, both of which won't match the modern exterior of my building. What would my options be if I went with vinyl but didn't want those frame colors?

Regarding flooring, the building is 3 stories high (garage at bottom, kitchen/living second and bedrooms third) I am looking at standard TJI for the floor between the bedroom and kitchen/living area but standard 12" joists for the kitchen/living floor (garage below) and the roof (nobody above).

I'm trying to achieve the best "STC per buck". The QuietRock product is NOT cheap - about $60 per 4 x 8 sheet. I'm willing to incorporate other sound proofing techniques/materials as long as the price is reasonable. Heavier insulation may be one of those options. Any advice is much appreciated!

I'm not sure though that your proposal to sheathe with
Hardie Board creates a third leaf. In any case, providing a drainage plane is essential, so don't forgo the spacing if you stick with that idea.

I would consider, as jgedney suggests, an EIFS exterior, which provides both sound and thermal insulation.

I would go for the best windows. I visited a client once near a major highway; when they closed the special sound resistant casement windows, the difference was amazing.

The 3 elements of an effective sound resistant wall are, in order of effectiveness, 1) mass 2), resilience, and 3) absorption.

A thick masonry backup wall or veneer is best. Thin masonry is not much better than other thin materials. In the absence of thick masonry it is best to use some kind of resilient mechanism to support one of the faces of the wall. These are usually channels with cutouts or rubber support gaskets. Quiet Rock etc attempts to provide resilience without adding thickness to the wall. If thickness is not a major issue there are cheaper ways to get the same or better results for less cost. Absorption using insulation materials is not very effective until the thickness is greater than 6" but even a thin layer will help prevent sound from traveling laterally from one crack to another.

Nothing reduces sound transfer better for the buck than deep or double studs and common resilient channels supporting drywall or sheathing. If the wall is designed properly the difference between wood and steel studs should not be measurable. It is also important to seal all joints and avoid long screws to insure that there are no acoustic short circuits.

The only effective windows I have seen were two independent windows set one behind the other in the opening. They are very effective in urban hotels in Europe.

Thermal insulation is a secondary concern because the home is located in Hawaii (it never gets below 60 degrees). My assumption is that standing concrete board off the plywood by 5/8" and allowing some airflow may reduce the heat gain slightly. We're essentially shading the plywood but I do realize that considerable heat will still penetrate. The insulation and remaining wall assembly should take care of the rest. Only the west-facing wall is really of concern and this happens to be the wall facing the freeway.

mightyanvil - I agree. Virtually everything I have been told about "soundproofing" was contradicted by acoustic professionals. But the interesting thing is that many "professionals" don't agree on certain aspects of soundproofing. Everyone has there own opinion on what a assembly should be and that things become more polarized once you throw the "budget" element into it. For example, greenglue will argue that their assemblies are the best bang for buck... and QuietRock will argue the same. Some people will swear by sound clips... others argue they increase wall assembly size and create "weak walls", physically. I'm just a confused mess. I'm worried if I hired someone, I would only get one person's opinion... and it may not be the best solution for my project.

I don't have much space to work with. Between the units will be an 8" CMU wall (fully grouted). I assume this should be sufficient for a party wall. Flanking shouldn't be an issue because the wall will run past the rooftop and into a rooftop deck area. Will an 8" CMU wall be sufficient for a party wall?

Space is a huge premium (interior space goes for about $600/sq ft in my area). If I increased the wall thickness by just 3", it will cost me $150 for every lineal foot of wall. 2" inches will cost me $100/lineal foot. Wall thickness is definitely a huge issue so I have to be careful of how I go about soundproofing. I need the highest possible STC with the thinnest possible wall. That is why I'm going with 2 x 4's and QuietRock.

I did consider the "double window" system but with only 5 5/8" thick walls to work with, I'm not sure how to get two window frames installed. Is this even possible? Maybe two single pane windows could fit? If so, I could go with two cheaper "standard-framed" 1/4 laminated window frames and mount them next to each other. Could this work?

When you set too many conflicting constraints for a building element you must lower your expectations for performance. In the end you will have to rely on the opinion of one person if you can't find a consensus. I would never take the opinion of a salesman over a professional.

Consider using site improvements to block as much wheel noise as possible.

You will never find a consensus for anything on the internet.