vgkg, unfortunately your window glass is all one unit. The two pieces of glass are sandwiched over a "Spacer" which creates the area which gas is pumped into. This inside space is also whee your LOW/E coating is applied to the glass. By not replacing it you may be in a dangerous situation with that damaged piece of glass. With it being such a big piece of glass you open the possibility of the damage escalating further with shards falling out. You also loose the overall strength of the glass with one sheet being cracked. I would strongly recommend replacing the glass unit. One huge benefit of replacing the glass is todays glass is so much better than your old glass. You'll notice a big difference between the old & the new.

I suspect you aren't going to be able to replace the glass with a thinner IG unit. If you end up having a glass company do the work, I'd ask if the existing IG has a Low e coating and if so, how much more glass with loe e and argon would add to the price. If the exising windows don't have Low e then I wouldn't get in on the replacement. If they do, I'd recommend the new IG with it.

With your glass being so large, you've got "double strength" insulated glass units (IGU). When one of the pieces breaks, not only has that glass been destroyed, but the sealed airspace has been destroyed as well. The whole unit usually is replaced in such cases. Is it possible to reseal the glass in the same frames? The answer is possibly "yes" from a technical standpoint, but 'no' from a practical one. The time and cost involved to retrofit such units would be much more expensive than buying new ones. I don't think any glass replacement companies would take the risk of trying to do this.

No matter how you look at it your going to have a hefty price tag on replacing this glass. It's well worth the extra couple bucks to get a new IGU with LOE/Arg. The heat you see daily in Florida can be very extreme. By not having the protection of LOE film & some type of inert gas such as Argon or Krypton, you'll spend more money trying to cool the heat that will bypass clear glass.

LOE or Low Emissivity coating blocks heat loss through normal clear window glass. It substantially increases thermal window performance while maintaining the appearance of uncoated glass. It reduces summer heat gain, and is also known to reduce the harmful ultraviolet rays, which cause fading of interior finishes. The coating reflects 40% to 70% of the heat that is normally transmitted through glass, while allowing light to pass through.

To see if you have a LOE coating on your existing glass just wait until it's dark out and grab a lighter. Hold the lighter up to the glazing unit and observe the reflections of the flame. There will be one reflection for each surface in the glazing assembly. A single pane of glass will have two reflected flames and a simple two layer insulated glass will have four reflections etc... Any surface with a low-e coating should reflect back an image of greater intensity and a slightly different color than the rest. Noting which reflection has shifted in color will tell you which surface is coated. Try the same experiment from the opposite side of the glazing. This should confirm your identification of the low-e surface. These reflection effects are the result of the fact that low-e coatings are somewhat more reflective than glass alone across the spectrum and so will appear to reflect back an image brighter than the other surfaces, and because they selectively reflect greater amounts of longer wavelengths and so they reflect back more red. This second effect is more noticeable in some coatings than others. Hope you understand this and it helps you out in some way. Good Luck!!!

I am agreeing 100% with Guy - with one slight qualification - and with the caveat that if the 1980 vintage windows in the Florida room are tinted then I would bet my paycheck and his that none of them are LowE coated.

First, if you are going to the expense of replacing this thing then get a LowE2 or LowE3 coating on the replacement - it is worth the extra cost. But (the qualification), I am less certain of the gas infill especially if the replacement IG is manufactured locally.

If the IG unit is manifactured by one of the major IG folks then I would say consider a gas infill. But if it is put together by a local glass shop then I would not consider it.

Very few folks in your area have experience dealing with IG's (dual pane glass) and even less (probably none) when dealing with argon or krypton fill. They probably have no idea how to correctly fill an IG space.

I would also strongly suggest that you might consider getting tempered glass in the replacement. It is relatively cheap insurance against future expensive glass replacement and a huge safety advantage in a window that large. The rock that broke the outer pane would have likely bounced off tempered without a problem.

Guy can tell you all about what broken glass can do to human skin....I am a big fan of safety glazing in many circumstances.

Thank You for the good info! Yesterday I removed the broken outer pane which was still hanging in place but shattered. It was brown tinted while the interior pane is clear so there is a striking difference now. I'll get some estimates and contact my home owners Ins to see what's covered with the $500 deductable. The broken pane was in a million tiny pieces designed to break in that manner? Ugh, one tiny pebble, so much headache!

Oh yeah, now that the window has been "cleaned up" it really doesn't look bad, just clear. I was also wondering about (just in case the replacement cost is prohibitive) if there's a product or service out there that could just add a coating to the remaining clear pane to tint it to match the other windows, or at least come close to a match and reduce the heat/light/UV coming through? Either a professional service or DIYO kit?

Hey Oberon, Nice to see your smiling face around. It's been awhile since we've collaborated on one of these questions. I hope life finds you and your family in great health and happiness. I've been so busy I hardly have time to visit the forums anymore. Winter was the worst I've seen in 20 years and Spring brought an avalanche. Feast or famine, that's always the way it works. Johan's having a slow one this year, as are the others. Take care my friend!

Sorry, had to say Hi to an old friend.

It would cost you more to have the coating applied than buy a new piece of glass. The coating is applied to the glass through a machine while it lies flat. It has to be done in a better environment than outside. It sounds like you have tempered glass if it broke into tiny cubes. That would also explain the thickness of the glass. Sounds like one heavy piece of glass!! Can't imagine putting that one in.

I know your trying to do everything in your capacity to save this single sheet of glass. I would call on a glass company down there and see what they would have to say about what you have. Maybe they have some options or ideas I don't know about or do.

Thanks Guy! Will contact the specialists in my area and make a plan. No problem on the Hi to an old friend, they are the best ones indeed.

Hey Guy! How have you and the family been, as well? I have been travelling a ton lately and also haven't been on line much at all. It has been a number of weeks since I have had a chance to drop in to the site.

Johann has looked much better the past few games - like every year it seems he waits until the all star break to turn it up a notch. I am sure everyone wonders why it works that way...and as always, great to hear from you. Glad to hear that you are so busy. With the housing slowdown it feels like a lot of folks in the industry are having to scramble a bit for the jobs that are available.

Vgkg - sounds like the original window was tempered after all from your description. So much for the rock bouncing off - obviously....

Ultimately, even the single lite is going to keep the rain out which is what windows are supposed to do. If you find that you can't replace the IG at this time, then a solar-reflective film wouldn't hurt to help block some of that solar heat from getting thru the clear singe pane.

You can go DIY or you can have a film-pro do it. If you plan to hire it out, then as Guy said, it might very well be more cost effective to replace the IG. If you want to try the DIY version then you should be able to get it done without breaking the bank...with the thought that it isn't as easy as it looks.

I also agree with Guy that the original window would have been heavy and no doubt awkward to install at that size.

Let's see - 4x8x1/4" - glass at 155lbs cu/ft - get the calculator out - 207 lbs for the glass alone, not counting the weight of the frame which depending on style could push this thing up to 300lb range. Wouldn't want to try that one alone!