As Mike pointed out, there are a number of conflicting and overlapping code issues involved. For example, Kritlyn's orginal question concerned impact glass. Technically, impact glass isn't actually required anywhere. A homeowner can use shutters or even plywood (with certain requirements/restrictions for plywood) and not need impact glass. Windzone requirements specific to impact glass are spelled out in ASTM E1996-05 and include several levels of protection required anywhere from a garden shed to "essential" structures such as hospitals, schools, police and fire stations. Within the windzone guidelines are levels of testing for the different types of structures within the specific windzones. It isn't particularly complex, but it is involved. The specific requirements do separate roof windows from vertical windows for example and also windows that are above and below 30'. As Mike pointed out, local codes can become much more (or less) restrictive and much more specific. Design Pressure, or DP, requirements also vary by location and windzone. DP is NOT necessarily indicative of an impact product. That is why some manufacturers can get away with saying they sell "hurricane" windows that are not impact resistant - they have met windload Design Pressure requirements, but remember that that window isn't specifically protected from the neighbor's flying lawn furniture in the event of a storm. It will require something to protect it from an impact. DP ratings do apply to specific windspeeds and as such may be mandated in certain areas. Often, the requirement is specified by the architect or engineer designing the home or the protection for the home...and it is quite possible to have different requirements for windows in the same house based on orientation and location (such as near a corner).

I'm putting my money behind bossyvossy. PVC is not only structurally weaker, it has a shorter lifespan. If you plan on "flipping" your house to an ignorant buyer who doesn't know the shortcomings of PVC windows, go ahead and use them. But if you plan on keeping your home or passing it on to the next generation, what sense would it make to install windows that are going to need replaced in 20-25 years? Is it worth saving a few bucks on the front end just to spend 100% or more of what you are planning to spend on today's less expensive PVC windows? A QUALITY aluminum framed window with a high performance finish will easily last in excess of 50 years. Plus, PVC is the scourge of the planet in both its manufacture and disposal whereas aluminum is totally recyclable. Help yourself and help the planet and go aluminum. They may not be as good as old growth wood windows, but they are more affordable and require less maintenance.

@Ron. Once again you have missed the mark, Ron. The hurricane testing standards were developed to reduce property losses only with no regard as to human safety. The insurance companies said that if something wasn't done, insurance costs would skyrocket in Florida or not be available at all. So structural engineers and the window industry got together and the testing standards that we have today are the result - far from perfect but somewhat satisfactory to the insurance companies. They hoped that by stopping the pressurization of the structure they could stop the roof from being blown off and thus reduce the amount of total structure losses. That is why it doesn't matter that the window is destroyed by the large missile impact. As long as it stays within the window frame and stops air from entering the building, it is considered an acceptable product. The fact that it is sacrificial and will no longer function as a window makes no difference. You might be better off understanding the topic than trying to psychoanalyze me. As I said previously, I'm not here to promote my product but rather to educate and inform the reader that impact windows are not the safe, ideal form of hurricane protection that they may have been led to believe. @Pensacola You totally understand my point. Thank you. I'm going to let this thread die before someone has it devolve into name calling and personal attacks that achieve nothing and only give good, informative forums like this one a bad rap.

If you want limited service life, go with the vinyl. If you want your windows to outlive the mortgage, get aluminum. The heat loss/gain differential works out be pennies a month. IG units vs. single pane seems to be about the same situation. Until someone perfects a way to control the internal airspace pressures, leaks are inevitable and the gas is gone well before the warranty. Nationwide leakage percentages published by the industry are low (1-2%) but regions like Florida and the Southwest run higher (I see dozens every month). Laminated glass with a low-e coating appears to be most cost effective and combined with aluminum frames would be my personal choice, but that's just me.