I have had the opportunity to deal with Chinese glass and windows on a few occasions. That opportunity included both laminated and tempered product as well as regular annealed.

Personally I wouldn't consider it for my home under pretty much any cicumstance. If you feel otherwise then I would wish you good luck.

What would be the advantage?

Michael

The home I'm building is right next to a busy freeway - with no sound barrier. The prices I received for double or triple pane products locally are insane. My requirements were vinyl frame, double pane 1/4" and 1/4" (one plate must be laminated) min 5/8 or 3/4" clear spacing.

Standard double pane windows are cheap and plentiful but they provide very poor sound insulation. The windows in China with specs I required were 60-70% lower in cost than similar spec product here in the states. My concern is with requirements and certification - if windows need any to be installed in homes here. For example, an electrician won't install a light fixture if it is not UL approved.

Windows imported into the US must meet US specifications. Part of the specification for safety glazing is the "bug" in the corner that identifies the glass as safety glazing. Part of the requirement is that the bug has to be in english - so it will be - from China or not.

The last Chinese window and door company that I dealt with had tested their product to required US specifications - and they failed - they could not meet those specifications.

But, they were not dissuaded by the results because they felt that the windows did meet "minimun specifications", in their interpretation of the specification (they did not), and that there were "ways" of getting their product to market despite the failures....

Tempering glass is relatively easy and I have no doubt that they can meet the requirements for tempering glass.

Laminating glass is a bit more involved, but again, the Chinese are in the process of taking over the windshield replacement market (a number of major US windshield plants have either closed or are in severely reduced production mode), so I know that they have the facilities to laminate as well. My concern is are they actually doing what they say they are doing?

Toys, tools, pharmaceuticals...windows?? I lack a certain level of trust in Chinese imports - but they are cheap.

Imagine this. Buying that window made in China, paying export fees and transportation and STILL be lower in cost?

I'd be worried, my friend.

Michael

I would stick with Chinese food, not their windows. They can't produce a product for import that hasn't been recalled.
If you can't find a product in this country that fits the bill, you're not looking .
Ron

I have to agree with both of you regarding the questionability of China made product.

I have a close friend that resides in mainland China and he has made a couple suggestions regarding manufacturers. One of the manufacturers he suggested built the curtain wall system for two luxury condominium projects in my area. I assume that a company that can mass produce often highly complex curtain wall systems of high quality could produce a few standard double pane windows. If the company you work with has a strong working relationship with others in the US I think concern should be minimal. China can crack out some junk, for sure. However I've seen a lot of junk cranked out of our domestic plants too. Another thing to consider is that a lot of plants in the US are beginning to assemble products ONLY and a good part or all the material is imported - often out of China. Legally, the companies are allowed to stamp "Made in the US" on their products granted all the assembly was done in the US. But this is really far from the truth.

Forunately (and unfortunately), China is improving their overall QC and this could mean more and more outsourcing of manufacturing. This will translate into lower costs for consumers but less work for our people.

I'm currently leaning towards working with a local outfit. His pricing is more than double that out of China but it's better than what I've been looking at (triple+). Thanks for your input. I'll do what I can to support my local economy but paying triple to quadruple for a similar product is beyond me.

Chinese made window bashing aside, I understand your desire for laminated glass for sound control purposes, but for your consideration I might suggest that an 1/8" opposite lite - versus 1/4" - with the increase in airspace width that results may give you slightly better sound attenuation results than using a 1/4" monolithic glass and a sacrificing airspace as a result.

For sound attenuation "wider is better". If you are looking at a 5/8" airspace with 1/4" mono glass - then the additional 1/8" - giving you a 3/4" airspace afforded by using 1/8" glass - would likely be advantageous.

Even more so, if you currently have a 3/4" airspace and can kick it up to 7/8" with the additional 1/8" then that would also potentially be to your advantage.

Interesting comments, Oberon. I did some of my own research online and it seems that if I need to reduce low frequency noise I need more mass. Your comments suggest less mass and more air space. Also, laminated glass seems to have a huge advantage (noise reduction) than monolithic, however you suggest otherwise. Now Im just confused!!! But seriously, let me make sure I understand this correctly.

Option A --- ¼" monolithic glass + ¾" airspace + 1/8" monolithic glass

Rather than:

Option B --- ¼" laminated glass + 5/8" airspace + ¼" monolithic glass

Are you saying that I would have better noise reduction (living next to a freeway) with option A rather than option B? Im not discounting what youre saying (and I value your opinion and knowledge) but this doesnt make sense to me. My understanding is that mass is key to reducing low frequency noise. And that laminated glass reduces noise much better than monolithic. How can that extra 1/8" of airspace have a greater effect on noise than the extra 1/8" of glass AND laminated vs monolithic (1/4")? What if I increased the airspace on option B by 1/8" Will this make option B superior to option A? Thanks for your help.

tcjohnsson,

Sorry that I wasn't clear in my previous post.

You definietly want the laminated glass if you want maximum sound attenuation.

You want option A - but WITH laminated glass as the 1/4" lite.

The three most common methods of reducing sound thru a window - in their order of sound-blocking effectiveness:
First is laminated glass
Second is a wider airspace between the lites
Third is different thickness lites within the IGU or Insulating Glass Unit

But, something I failed to mention in the orginal post is that downsizing the mono lite also gives you an effective "different thickness lites within the IGU". I didn't mention it in the original post because I was thinking "overall" and not lower frequency attenuation that you will need. Your post kind of "knocked me on the head"...

Which brings up the next question - since the laminated unit would be made up of two 1/8" annealed lites plus a .030" PVB interlayer, should it be considered as the same or as a different thickness than the monolithic 1/4" lite? We shall see.

Also, is a wider airspace an advatage at all frequencies - or at specific frequencies - or at higher frequencies? Again, we shall see.

Also, is thicker monolithic an advantage at specific frequencies? Again, we shall see.

Okay - numbers.

- product STC overall 100hz 5000hz

1/4" lami - (1/8" x .030 x 1/8") 35 25 46

3/8" lami - (1/8" x .030 x 1/4") 36 27 52

1/4" mono lite 31 23 41

1/4" mono / 1/2" air / 1/4" mono 35 29 58

1/4" lami / 1/2" air / 1/4" mono 39 28 56

1/4" lami / 1/2" air / 1/8" mono 35 32 57

1/4" lami / 1/2" air / 1/4" lami 42 26 58

1/4" lami / 1" air / 1/4" lami 46 28 62

Wider airspace an advantage for "overall" performance and at higher frequencies. But, at 100hz the wider airspace does not offer an appreciable advantage.

Thicker mono lite is a definite advantage at higher frequencies but not so much at lower.

The best performer at lower frequencies is 1/4" lami / 1/2" air / 1/8" mono...which happens to be closest to option A - only with laminated glass rather than mono as you listed for option A.

And the increased airspace in option A will benefit the overall IG performance, but it won't really do anything extra for the lower frequency performance.

And the number columns were good in the "message" box but won't line up in the submitted box - hape you can make sense of them!

Sorry Oberon! I didn't know you responded... until now! Anyway, are you still around? I hired an acoustics engineer after racking my brain about this for hours on end. I'd like to share some of what I've learned (and paid for).

Welcome back and no trouble.

I am curious what he had to say...

Oberon -

I found a window manufacturer - Oceanside Aluminum.

They make a triple glazed window with 1 1/4" IGU.

Since these windows are going into a home right next to a freeway (as discussed, low frequency noise is most noticeable), would you recommend triple glazing over dual glazing?

My thoughts are -

1/4" lam + 3/8" airspace + 1/8" lam + 1/4" airspace + 3/16" lam

The 1/8 lite does not need to lam but the window rep said it would increase the STC.

What concerns me is that the windows being installed are XX sliders (both windows slide horizontally, independent of each other). My concern is the seals won't be very effective with such a window type and all this work to get the glass right could be negated by the inherent "un-soundproof" qualities of such a window type. Are these concerns warranted?

I told the manufacturer that I would prefer to put two windows in tandem (two dual sliders on top of each other). This is similar to what Soundproof Windows does - throw one independent window on top another. But the rep said this is not necessary and the XX slider would provide an STC high enough despite being right next to a loud freeway.

Wouldn't a insulated glass unit w/laminated glass + a single glazed unit w/laminated glass on top of it be considerably more effective than the triple glazed unit? The benefit would be in the huge air space (about 2") between the exterior and interior windows. But then again, maybe this will only help with high frequency noise?

This is driving me crazy! Thanks for your help!

Did the rep give you an STC number? Or did he just say that it "will be good enough"?

The triple as you describe it should give you very good numbers, but as you are thinking if the windows aren't tight then the very expensive glass package ends up being a waste of money.

Something else to keep in mind is that a great STC may not indicate great performance at the frequency that you want to block - but that may be tempered because we hear different levels of sound at different frequencies...nothing simple.

For example (borrowed from ASTM E90 - Airborne Sound Transmission Loss, 1/3 Octave Band Data):

"Tested values (in dB) for an STC 52 window shall be:
1/3 Octave Bands: 125 160 200 250 315 400 500 630 800
Transmission Loss: 28 39 42 44 45 50 52 52 53
1/3 Octave Bands: 1000 1250 1600 2000 2500 3150 4000 5000
Transmission Loss: 53 55 57 62 64 68 70 75"

First thing is to see what the STC is for their proposal.

Second is to find out how tight the window - air infiltration in CFM.

Again for example (borrowed from ASTM E283 - Rate of Air Leakage Through Exterior Windows, Curtain Walls and Doors): "Air infiltration at a test pressure of 6.24 psf (50 mph) shall not exceed 0.0 cfm per sq. foot as measured in accordance with ASTM E283."

You can even calculate air leakage to sound transmission loss using the formula
10 log10 [1+ .012(L/S)^10STC/10]
but who really wants to go there? You just want a quiet window...

Wow, that's crazy! I am waiting to hear back from them regarding the air infiltration numbers. They gave me one but it seemed WAY too low. Also, I have decided to not go with a triple pane window.

I have been told my my acoustical engineer that a single pane laminated lite (9/16" thick including 0.060 interlayer) will provide an STC of 39. This is for the glass only... so I'm not too sure what the number would be if you take into account the actual window (frame, mechanical, slider, etc). We were also looking at another option - 1/4" lam + 5/8" airspace + 3/16" standard glass would only provide an STC of 36.

He said going with the double pane option is not going to give me better numbers. In addition, a single pane laminated would provide significantly better attenuation in the low frequency range and considerably better in the higher frequency range than the double pane option. However, he did say that the performance of a double pane window would be slightly better in the "middle frequency range".

Do you know what the frequency highway/freeway noise consists of and which frequency is most "annoying" to people?

Do you think I should do away with the double pane IGU option altogether and just go with a thick single pane laminated? Are there pros and cons to going double or single pane? Thanks again in advance. You have been INCREDIBLY helpful.

Oh, and the manufacturer put the STC number for the 9/16 single laminated glass at 41. And he also said that differing the thickness of the glass in the laminated glass itself makes a significant difference. For example, a single pane laminated lite consists of 2 glass pieces. One is thicker than the other (I think it is 6mm and 8mm + the interlayer). In addition, he said 41 STC is "more than enough" sound isolation for most people. Even being within 40 feet of the freeway. Do you think 41 (or 39 STC) is enough for being in a bedroom RIGHT NEXT to a busy 6-lane freeway?

Good morning,

Feeling like a little bit of "light" reading?

Use this link and get ready...you are going to enjoy this, I think.

Nice read! But it's 1:30 a.m. and I still need to go to bed! I got to page 25 and then my brain farted... and I started seeing double. Or at least I think. Notice how figure 1.15e and 1.15f are the same? Either that's a mistake or I'm REALLY tired.

Hey Oberon, I just posted this on an AVS forum to a guy named "Ted". I figured you may have something to say about this single lam choice and its performance in my application. Seems like a winner? ....

The specs of the single lam (3/4" overall) are: 1/4 tempered + .060 PVB interlayer + 1/2 tempered. The manufacturer of the lite is Arch Aluminum and Glass Co. The manufacturer of the window is Oceanside Aluminum in California. The manufacturer claims an STC of 41 for the lite but has no testing data for the actual window itself. The air infiltration number on their windows comes in at .09 so I'm assuming the frame performance of their sliders and awnings is desirable. My acoustics engineer decided the single lam is the best performer in the lower frequency area, which is most critical for my application. In order to match the low frequency performance of the single lam, I would need to go with a huge IGU - at least 2 1/2" thick including a 2"+ airspace and just as much glass with one lite being laminated. Finding a window manufacturer with that kind of IGU is difficult and likely not an option for me.

I found that the OITC numbers for single lam windows are superior to double pane IGUs (w/one lam).

I found this site along with lots of STC and OITC data on various glass configurations -

http://www.saflex.com/pdf/en/archi/S...ical_Guide.pdf

The data shows that a single lam (the window I have spec'd for my project) consisting of 1/4" + 0.60 PVB + 1/2" has an STC of 41 but an OITC of 36 which is extraordinarily high. To match that OITC in an IGU configuration, I would need to go with a significant 2" airspace and similar amount of glass (in weight/mass). Apparently, losing the airspace altogether is beneficial for applications where traffic is the main source of noise. A single lam performed better than all IGU configurations w/single lam and Here is a link to the manufacturer of the laminate and its performance -

http://www.archaluminum.net/technica...ting_chart.pdf

Any caveats with this decision of going with a single lam window? I asked about the thermal value/benefits of going with an insulated glass unit over a single lam but the manufacturer said it would be nil as I'm in a temperate climate and the laminate itself contains a Low-E coating (for heat reflectance). Seems like a single lam configuration is a no-brainer? Not only that but now my entire building will have hurricane proof and security windows which should reduce my homeowner and hurricane policy premiums a bit.

After this research and the recommendation from my acoustics engineer, I wonder why any window manufacturer would suggest using an IGU unit if the install location is in a temperate climate and traffic, train or airplane noise is a concern. Am I missing something?>>>

Whoops, looks like the addition of symbols to demarcate where the post began and ended cut off a part of it. Here it is again -

Hey Oberon, I just posted this on an AVS forum to a guy named "Ted". I figured you may have something to say about this single lam choice and its performance in my application. Seems like a winner? .................................

Ted, I have decided to go with a single lam on ALL windows for my project. That includes those that face the freeway, those that are perpendicular, and those that face away from the freeway.

The specs of the single lam (3/4" overall) are: 1/4 tempered + .060 PVB interlayer + 1/2 tempered. The manufacturer of the lite is Arch Aluminum and Glass Co. The manufacturer of the window is Oceanside Aluminum in California. The manufacturer claims an STC of 41 for the lite but has no testing data for the actual window itself. The air infiltration number on their windows comes in at .09 so I'm assuming the frame performance of their sliders and awnings is desirable. My acoustics engineer decided the single lam is the best performer in the lower frequency area, which is most critical for my application. In order to match the low frequency performance of the single lam, I would need to go with a huge IGU - at least 2 1/2" thick including a 2"+ airspace and just as much glass with one lite being laminated. Finding a window manufacturer with that kind of IGU is difficult and likely not an option for me.

I found that the OITC numbers for single lam windows are superior to double pane IGUs (w/one lam).

I found this site along with lots of STC and OITC data on various glass configurations -

http://www.saflex.com/pdf/en/archi/S...ical_Guide.pdf

The data shows that a single lam (the window I have spec'd for my project) consisting of 1/4" + 0.60 PVB + 1/2" has an STC of 41 but an OITC of 36 which is extraordinarily high. To match that OITC in an IGU configuration, I would need to go with a significant 2" airspace and similar amount of glass (in weight/mass). Apparently, losing the airspace altogether is beneficial for applications where traffic is the main source of noise. A single lam performed better than all IGU configurations w/single lam and Here is a link to the manufacturer of the laminate and its performance -

http://www.archaluminum.net/technica...ting_chart.pdf

Any caveats with this decision of going with a single lam window? I asked about the thermal value/benefits of going with an insulated glass unit over a single lam but the manufacturer said it would be nil as I'm in a temperate climate and the laminate itself contains a Low-E coating (for heat reflectance). Seems like a single lam configuration is a no-brainer? Not only that but now my entire building will have hurricane proof and security windows which should reduce my homeowner and hurricane policy premiums a bit.

After this research and the recommendation from my acoustics engineer, I wonder why any window manufacturer would suggest using an IGU unit if the install location is in a temperate climate and traffic, train or airplane noise is a concern. Am I missing something?>>>

There are IGU windows available with sound attenuation values that exceed those that you mention, but that in no way diminishes the sound performance values that you quoted - which are darn good.

I would suggest that even in a moderate climate an IGU window is a good investment from an energy performance standpoint. Obviously if you live in a more extreme climate (hot or cold) then the value of a higher performance window is potentially greater.

I am thinking that the 1/4" + 0.60 PVB + 1/2 is going to be fairly expensive? Of course any window meeting the numbers that you are looking for is going to be costly.

Expensive is an understatement. With shipping, the cost on 55 windows and doors is a staggering $90,000. And I was incorrect about the thickness. Here are the specs -

8mm tempered + .060" PVB interlayer + 6mm tempered

Total thickness is .6112" or just a hair (1/100th of an inch) less than 5/8".

According to the reference guide you sent me, this should yield an STC of roughly 40 and an OITC of 36 which are the numbers for:

9.5mm + .030" PVB + 6.4mm (overall thickness 0.66")

This does yield about 2mm of additional glass mass but provides only a 0.75mm vs a 1.5mm PVB interlayer.

The STC isn't what excites me... it's the OITC. 36 is very impressive for a glass assembly.

Now I'm just worried how well the frames will perform.

IGU glass is usually only beneficial if the ambient temperature outside and the (preferred) ambient temperature inside is significantly different. In Hawaii, it is rare to have a temperature differential of more than 15 degrees (temp extremes range in the evenings from 55 degrees (low) and in the daytime 90 degrees (high)) so I'm not really that sold on IGU units here. As long as the PVB interlayer has a Low-E coating with heat reflective properties, single lam windows should not transfer a significant amount of heat and only then should it do so when the sun is directly hitting the glass.

To achieve an OITC rating of 36 in IGU, I would need more mass and a overall IGU of over 1 1/2". So far, the largest IGU I could find was 1 1/4" as standard. To achieve that OITC rating I would need more than 1 1/4" to work with even with DOUBLE LAM. It was pretty much my best option to get the OITC. I have pretty much ignored the STC figures as I understand the OITC reading is much more important when considering noise from traffic. Thanks again for all your help.

Using a 1.524pvb interlayer will give you about a 1db to 2db gain in noise reduction versus using a .762pvb interlayer. You might also consider asking your glass supplier about sound-reduction interlayers as well.

There are four companies worldwide that manufacture laminated glass interlayers (outside of China). Two of them offer sound reduction PVB as an option. The laminated glass folks that you mentioned in your earlier post will be aware of that option if you ask them about it.

Also I am curious why tempered glass? ONe thing to keep in mind is that tempered glass will have a certain level of distortion. Thicker glass typically less so than thinner glass. Adding two lites of tempered in a laminated make-up can result in significant distortion thru the glass due to non-parallel surfaces because of tempered distortion.

Thanks again, Oberon. I've read what you said about SGP vs PVB interlayers and that PVB is superior acoustically. However, in order to have the windows wind rated to hurricane requirements, I must use an SGP interlayer. Would you advise going with a SGP interlayer vs a .060 PVB interlayer?

Also, I'm only accustomed to hearing .030 and .060 for lam thicknesses with SGP being a standard .090. What is 1.524 and .762? Are these 1/8" specifications?

The manufacturer claims tempered glass is 4 times stronger, thus decreasing the chance the glass will break upon impact. Is this not true? Is all tempered glass subject to distortion? Should I be concerned with a 6mm and 8mm tempered sheet in one lam?

Sorry for the confusion. In your previous post you mentioned PVB in millimeters ("...0.75mm vs a 1.5mm PVB interlayer."), so I switched to millimeters in my post somewhat out of habit.

While some laminators use inches for the interlayer thickness - .030, .060, .090 - others use millimeters - .762mm, 1.54mm, 2.286mm. When you used millimeters I assumed that your supplier was talking in metric so I went that way.

Not much different than glass; glass can be referred to as double strength, 1/8" and 3mm for the same product.

And tempered glass is considered to be four times stronger than annealed glass, and at the thicknesses that you are considering distortion potential is minimal, but the possibility is there. Take a look at some large storefront windows when you have the chance and notice the distortion in the glass. That is the nature of tempered. Distortion in the storefront windows may be very minimal so that you don't even see it, or it may be really obvious - often depending entirely on the skill of the operator.

I had mentioned in a much earlier post that tempering glass is easy, but tempering glass really well (flat) takes good equipment, technical skill, and a bit of artistry from the furnace operator.

I am not entirely familiar with the hurricane requirements in Hawaii, but I seem to remember that the islands used the basic ASTM E1886 and E1996 reqirements - but I could be wrong about that...

You will not meet large missile, or ASTM missile D (basically the same thing), impact requirements using either .030 or .060 interlayers. For consistent impact performance you need an .090 interlayer - either PVB or SGP. So, based on your last paragraph, what sort of impact are you considering when you mention "...thus decreasing the chance the glass will break upon impact..."?

It is true that tempering the glass will help keep an errant baseball from potentially breaking your glass, and it will add a good bit to the level of windows that the windows can handle without broken glass, but if you are thinking of impacts from flying palm trees or coconuts in the event of a hurricane, then tempering the glass really doesn't add a lot to the overall impact performance.

I am also a bit puzzled about needing SGP for windloads. You are using some very thick glass and considering tempered as well, so what windload are you thinking of meeting that you need SGP?

I like SGP, I think it is an amazing product, but for sound applications I would suggest that it is not the best choice.

Also, which island are you on? I lived on Oahu from 1981 to 1984.

I'm on Oahu and the project is right in downtown Honolulu. A very busy and noisy location.

Thanks for the clarification. I don't know why window manufacturers do that - intertwine metric and standard into the same specification. It gets really annoying.

I think I'll take the risk with the slight distortion if it means stronger windows. No palm trees nearby to go flying into the windows but I have a larger concern - neighbors with REALLY old homes. I'm afraid a good storm will shred these 1930's stick homes, subsequently torpedoing debris into my home.

The hurricane insurer is requiring a statement from the window manufacturer. And the window manufacturer seems to think SGP would be required to be "hurricane proof", thus qualifying for the discounts.

One other consideration is going with a single lam vs an IGU with one lite being lam. The problem I see is that the OITC performance would suffer considerably if I try to go with an IGU when working with a 1.25" overall IGU thickness. The tests show that a single lam (5/8" thick) would perform best in the lower frequency ranges and better than any IGU configuration that can fit into a 1.25" IGU. But the downside with a single lam is energy efficiency. The homes are being built as zero energy, meaning they will generate as much of their own energy as they consume. The manufacturer said the LOW-E coating is on the laminate itself and therefore the window performance is good when sun light hits the glass directly. Don't know if this is true or not...

I would think the additional thickness of the SGP would balance out the acoustical performance at least in the low frequencies. Since this home is being built right next to a freeway, would you recommend SGP over a PVB interlayer? I don't think PVB comes in a .090 thickness but I could be wrong. All the tests and assemblies I have seen do not show PVB @ .090 thickness, only SGP.

Where did you live on Oahu if you don't mind me asking?

SGP is not intended to be an acoustical product. While there may be some slight advantages to SGP versus monolithic glass (very little I suspect), an SGP laminated glass window will not stop sound - even at lower frequencies - nearly as well as will PVB in the same application.

While there is really no such thing as being "hurricane proof, PVB is readily available at .090 interlayer thickness. Interlayer at.090, whether PVB or SGP, is pretty much the standard for impact performance in hurricane prone areas.

And while I like SGP and I consider it to be a superior product when used in hurricane prone areas, I am very curious why your window supplier said that SGP is the only option to "qualify for the discounts". What is he basing his assessment on?

LowE coatings are also readily available with laminated glass. The coating is applied to the interior of the laminate and the result is SHGC that is very close to what you would get when using an IG unit with the same coating in the same situation, however the coating will not improve the U-value over that of the same glass without the coating because the coating needs an airspace to improve U-value - something that laminated glass doesn't offer obviously.

And no trouble about where I lived on Oahu, heck, I asked first!

Anyway, I lived down near Pearl City in a Marine housing area called Manana (and I no doubt just wrecked the spelling), just up the hill from the Pearl City Tavern - assuming the Pearl City Tavern is still there. I was Navy, not Marine, but about 1/3 of the residents in the housing area were Navy with 2/3 Marines.

I heard from a neighbor that in Miami-Dade county they do not allow imported windows from China to be installed. Is this true?

There is no prohibition anywhere in any of the Dade county requirements against Chinese made windows or components

Oberon... just wanted to give you an update on my situation. The windows arrived last month and were recently installed on the project. I'm going for LEED Platinum (originally it was LEED Gold)... the first of its kind for a multi-family in the state.

We had a big problem when the windows arrived, and you're not going to believe this... but they were NOT Low-E. Obviously I ordered them as Low-E but somebody down the line dropped the ball. In any case, the window manufacturer is taking care of the issue and will, at their cost, apply tint to the entire project.

I ended up going with 1/4" + .90" PVB + 1/4" for a total glass thickness of 19/32. The STC and OITC ratings were almost identical to the 8mm + .60" PVB + 6mm

I paid more for the thicker PVB interlayer but it does meet missile impact ratings and I'll qualify for discounts on hurricane insurance. And of course the acoustics improved with the thickest available interlayer. With freeway traffic at full capacity/full speed, the difference between having the windows open and closed is dramatic... and this is without the seals in place yet.

So now back to the tint... the manufacturer has connections with 3M so they recommended I choose a product from them (though I do not have to choose their product). After researching all their available films, I found the PR50 film from their Prestige series to offer the best combination of SHGC, interior reflection and visible light transmitted numbers (my three most critical features).

http://www.3m.com/us/arch_construct/scpd/prestige/products.html

The property offers these unique exterior planter boxes (on second and third levels) that are lit up at night. A high interior reflectivity number would mean you could not enjoy these "mini-gardens" outside the specially designed windows... as you would only see a reflection of yourself and everything in the house - as opposed to the garden. And this tint seems to offer a very low interior reflectivity number. This is in addition to very good SHGC and decent light transmission numbers.

You are definitely the authority when it comes to windows... so I'm thinking you may have an opinion on tints. As always, your input is ALWAYS appreciated.

Regarding the insurance people (Allstate), I think they didn't know what they're talking about. I'll let you know what they say about the .90" PVB interlayer.