france, rebuilt -- so before all our glass was domestic and after world war ii it became foreign. they had all the new factories and we had the old ones. so they set up a product, and they would pour it and polish it automatically, so it was perfectly flat. and that was the origin of the polished plate. then, subsequently a process came up called float glass. and that was just revolutionized the industry because they poured glass out on a bed of hot tin, voluntary-in tin. why this -- vol tin tin. how they came up with that -- they just poured it on the bed and it was self-leveling and they made it so fast, cooled it

down -- i mean you go to the factory in stockton and it's just like making cellophane or whatever. this comes in, comes out, bam. and it's now, you know, inexpensive and quick. and so the word -- technically it's not polished but it's just plate. it works. and so the question is how thin do you want it. so then your window glass is done the same way now. so it's all done on this little thinner. what we have here is a product -- again, 3/16. this used to be called -- again, the old term was crystal. if you talk to somebody my age, they would say -- because 3/16 was always poured glass and always crystal. they didn't do a twin ground. so it is the same thing as the

quarter inch. and you still see it around because they put it in where they're trying to lighten a way. you want to put it in a window so it's not so heavy on a double-hung. it's a good product, but again, you know. you know, it's like window glass, you just have to hit it just a little harder. plate glass, same way. you know, this is what essentially was in i-magnum. this is what's in the mills building. this is what's in the rust building. this is what's in th in the hurt building. there's putty around them. they're going to shift. the wood kind of comes and goes. so it takes quite a bit to break a piece of plate because -- i mean you can -- this will take quite a bit of vertical weight

but if it gets bound or whatever, you know, if you just get it in the wrong spot, that's what happens. >> we're seeing some major high rises going up near the bay bridge and south of market and i'm wondering what kind of glass is being installed in those towers, and what will be the effect in an earthquake. >> ooh, excellent question. >> oh, boy. i think i will -- the right answer is when you come off of that part of bay, i always get in the left-hand lane. >> [laughter.] >> but there are -- those are tempered. and, you know, presumably, they will shift. and what it depends on how much this whole thing swins, whether there's enough give and take in those frames so that they don't crack. i have seen tempered glass in the los angeles quake, where the tempered glass actually kept the building together. it was acting like plywood. big surprise.

the tempered caught right at the frames and it was the tempered clearly that was keeping everything together. the building was going this way, and the glass was acting almost like a sheer wall. other times it totally collaps collapsed. seismically, ooh, that's a laurence question. >> they have limits on what both the transient drift and permanent drift is allowed to be, how far they are allowed to sway and how far they're allowed to be out of plumb. what they calculate it to be they come up with a resilient system of setting the glazing so that at the levels of drift there should be no pressure placed against the glazing. so that's the design. we will wait for a big earthquake and see how it plays out. but should be okay. the drift issues are things that we've been talking about for these high rise buildings. what are appropriate drift limits, and how much can a 600

foot building be permanently displaced and still be an acceptable building. how long can we expect the glazing in one of these new buildings to last? >> the state of california pushed the idea of, ooh, insulated glass is the answer to everything. it will keep energy down, and heat in. this is mandated, insulated glass. the problem is that they -- the public is not fully aware that insulated glass does not last forever. and that in time, it will -- it's reliant on a seal around the perimeter, and it will fog up. and it depends on the manufacturer of the kind -- who manufactured it, what kind of guarantee do you have. and sometimes that guarantee could be as little as a year, or five years, for some of the cheaper stuff. the best stuff, they're garden 10 years. >> what about the glass itself.

in my house we have hundred-year-old windows. >> the glass will be there forever but the thing inside will fog up in insulated glass. if you're lucky, you can get 20 years out of something, or 25 would be a lot. in these high rises, the probs -- the homeowners associations don't always realize that so when they put money aside for repairs, -- i'm president of the four seasons homeowners association and we're putting money each year towards replacement of the windows. there are other associations that are not doing that, and sometimes they come up with a big surprise, and say all of a sudden they get this 75,000, 100,000 assessment. it's not something i guess that the city can legislate, perhaps, but -- >> that's interesting -- >> but it's something everybody needs to know. there's a life to this product.

>> there's an inplied did youribility to the code but doesn't stay what it is. we often approve materials and the code says when we approve alternative methods of materials, there's eight specific lets which include safety, health, fire assistiveness, security, durability is one of those things. when someone says i'm going to use this product and i think it's equivalent to what the code requires one of the questions is how durable will it be and that raises the question what is the durability that you would normally get out of a product that is approved by the code. as we move towards these so-called performance design standards where they say i'm going to perform like the code even though it's not a product that meets the code, we're more and more asking the question, what if the regular code expect for all these things, fire resistance, durability, sanitation, so on. durability is one of the big

questions that we have not yet really wrestled with sufficiently. so if you were to say we're meeting the code, i would say what does the code require for durability. >> in terms of safety, why is glass in high rise buildings not laminated? >> sometimes it is. it is seldom, but the issue that we were just talking about could be -- is true for laminated insulated glass, or tempered insulated glass. it's the insulation that goes bad, not the glass. >> but we were talking about skylights, skylights were tempered, we had a problem with chardz coming down. >> and to answer the question, yes, laminated glass is very often used for glass. and we do use quite a bit of laminated glass.

it's ordinary, laminated is two pieces of window glass together, with a pbb in between. ordinarily it's 030 or to meet safety requirements and they put a little bug on the corner that says what requirements that meets. >> if you use a piece of safety glazing it is required by the code to have the little stamp that's permanently etched into the glass or attached somehow. so that you can see what the safety glazing requirements are being met. >> sometimes, though -- sometimes, if for example you have a french door, and you've got 18 lights that are about 10 by 12s, you may, sometimes, talk the inspector into say, hey, i don't want to see american tempering, tempering, tempering, as an advertisement on each of these stupid little

panes. this is silly. suppose i give you certification that i bought all of these at a tempering or laminating factory, and i put one at the bottom of the panel. sometimes, you can talk your way into that. >> and in fact there's a strange exception in the code that says you only have to list those in a french door with many lights for the bottom pieces are lower than 18 inches off the floor and for the top pieces that are more than -- and anybody remember what the details are? i think it's 40 inches. so the middle ones, where you're not at arm level pushing through or kicking, don't actually have to meet the same standards. >> but they have to meet the same standards of safety, but maybe not the same standards of -- >> labeling. >> -- labeling. and so sometimes it comes down to just common sense, but other times, you know, sometimes you have to just follow the letter of the law. >> common sense in the building

code. okay. laminated glass -- >> so laminated glass is actually a fairly strong material. you know, again, if you hit it in the center, it is. it's a little weaker on the edges because what happens is it can kind of chip, and sometimes it will run, or whatever. so the edges -- because essentially you're talking about two pieces of eight inch glass. the edges are a little bit fragile. but, you know, that's what happens. essentially, you've got point of impact there, but it all stays together. and so in a quake or whatever, in an accident, auto glass, we used a lot of that in the auto industry, a lot of lamination. so this is what works pretty well for that. plastic, you know, plastic is

easy. we're doing more complicated plastic, but great material, except scratches, it does all sorts of things, and it burns. not the perfect product. another instance that we're talking about, that is what do we do with mirrors. mirrors are essentially quarter inch glass, with a silver backing. and so the -- how do you protect those. these can't be tempered. they can't -- technically they can be but when you temper something, it puts a slight wiggle in it so then that mirror becomes a funhouse mirror. not good for retail, particularly. what we do, and this is required for sliding wardrobe doors, where it's a door, and it's moving, is to put the safety backing on the back of it.

so the mirror will break, but it will stay together by virtue of this category two. it's got like fiberglass mesh going through the back of it. it's still a mirror. sometimes we use this around bathtubs, so in case you get up, and... so it will break. but it's still holding together. >> is there another insulated glass that's available, besides doing that layer with the fog, that will -- you know, that will break? >> no. the glass is all fine. and there are different kinds of things you can put in. you know, you can put in a argo, some of them -- you can put in kind of like a vacuum. there's lots of things that -- and they have come up with better kinds of sealants. now frankly it's a better product than was made years ago.

so it does hold up better. but it's sometimes like a double beautled seal or a silicone then a beautle and there's a des cant which resists moisture in that little tin frame around it. they're doing everything they can to keep this thing together. the problem primarily is if the bottom -- if that seal -- if the bottom part of the glass, if your weep holes get gummed up and the glass finds itself sitting in water, not draining quite right, water and that sealant is dynamite so that makes it fail sooner. so the first thing you want to do is go home tonight and clean out your weep holes and make sure that everything is draining through your windows. but it's only going to last at this point, technology-wise until they come up with a better product and better sealants.

25 years is a wonderful thing for laminated glass. >> in the building department i see people coming in and replacing windows that they have replaced already, they replace with double glaze -- well 10 years ago, 15 years ago, and the seals have improved. but i see many people replacing them again and we will see them being replaced again if they can last another 20, 25 years. whereas the windows in my house might be a hundred years old but they're not double glazing. i think the state is in their push to have energy efficiency, requiring dual glazing, or other similar standards, is actually not looking at the long term durability issues from a like cycle cost for homeownerses. so what's an alternative that meets energy standards? clearly drapes that are insulated, or some other form of shutters, where you actually are -- where you're not trying to create and maintain a

permanent seal between the two levels, is a very effective way, and probably would meet the state energy requirements. nobody is pushing that. everyone is say i've got to have insulated glazing in my house and i think there are other creative ways with much better life cycle outcomes for the property owners. >> primarily design. if you have essentially like an awning or something that's going over the window on say a certain exposure, the use of a tinted glass would also reflect a certain amount of heat. >> what about e-glass? >> low e? >> uh-huh. >> low e glass has like a film on one side that makes it particularly effective in insulated glass. but it can't, at this point, be used by itself because that e-film washes off. another product that we did is -- these were stainless steel grids that came down, motorized

grids that were fascinating. and they also were of course protection for the house. you couldn't break through the stainless steel grids. but it was essentially a screen that came down over the exterior. >> there is a wonderful example of that in san francisco. when you go to the area where the new giants ballpark is, the old san francisco fire department pump station, which is at the corner of second and townsend streets, which is now converted to the fire department headquarters. they used to have gigantic steam pumps and pumped it into the high water pressure system, which is all over the city, the big hydrants with the colored tops. now they have small diesel pumps so the rest of the building is used for the headquarters. if you look at that building you will see, above the windows, are large metal cases that hold

rolldown shutters, that were intended so that they could separate the building from another 1906-style configuration, and continue to pump water out of the bay to this separate water system for -- so that they can -- and it was put in place after the '06 earthquake, when of course all of the water supplies failed in the city for fire protection. it's a great building. >> next question i have is if you can describe what's the difference between glass and glazing? >> glass is the noun, glazing is the verb and a glazer is the person that puts in the glass who glazes the glass. so glass is just the term for any one of these products, are glass. glazing is the process of putting in that glass, and you would put it in sometimes what people would call a glaze or putty.

that's -- and -- the a archaic name of the man that puts it in is glazer. >> is there a way to create a more effective glass without the air-space issue? >> what happens is that air-space in between does not transmit heat because the two -- the inside and outside pieces of glass are not touching. >> the lamination is actually an insulation? >> it's not. if you put a piece of plastic in between those two pieces of glass, essentially the heat goes right on through and so does the cold. >> and so does noise by the way. >> i'm talking more about having a thermal break like some window companies have a thermal break in their system so there's outside and inside aluminum. >> the thermal break is plastic that they use in those windows

but it doesn't give you the same performance that an air gap do does. and talking about acoustics, it's very -- one of the great misconceptions is that insulated glass, with that air space, gives you acoustical protection, when in fact it does not. it's not what you use for an acoustical problem. what you need -- i mean what's giving you some protection there is the fact that you've got two layers of glass. but the sound beneficiary -- beh pieces of parallel, the sound goes right on through. what you need is a piece of laminated glass -- your best insulating for sound is a piece of laminated on both sides, and an air space, or just a really thick piece of laminated, using different thicknesses of glass so they vibrate at different

levels. we use a lot of material where we have quarter inch on the outside, and 060 interlayer, and a piece of 3/8 on the inside, they're vibrating at different levels and the insulating is turning them down and that really cuts down sound. san francisco has become far more noisy and we do a lot of acoustical installations. the fact is the thicker this glass gets, the more it insulates against sound. so it's just you keep throwing money at it, and the sound goes down. the problem is that, you know, your walls may not be as -- you don't want to have the glass be more advanced than your walls, or the fact that you've got an open window, you know -- you have to seal off anyplace that air is going to infiltrate. >> the building code changed in 1974 to require sound

transmission assemblies be placed between units, apartments, his in new buildings, or condos, and to reduce outside noise inside residential units at the end of 1974. and it's not just the window assembly, but it's the whole building facade assembly that has to be put together in a way. and it further says, in the building code, in these requirements, that you have to be able to properly ventilate your residential unit with the windows closed. you can't be requiring to meet the residential ventilation requirements by opening your window because then obviously you're not meeting sound transmission requirements. so charles assaulter, you work with charlie, an old friend of ours that i went to high school with. >> really. >> really, in high school. he does a lot of this in the city and he's come and given us one of these brown bag lunches with acoustical separation and talked about just what he's saying, using different

thicknesses of material. the assembly has to go beyond the glazing, it has to be the building wall assembly that reduces outside noise. >> tempered glass is designed to take impact. that would have broken the window glass or the plate. i'm trying really hard. this doesn't want to break. let's give it a real... you know, so it's a good product. it's interesting. this center is the strongest part. the weakest part is at the edg edges. it takes quite a bit of impact, as you see. but -- in a quake, when they say don't leave the building, you know, there's a reason.

you're probably better staying inside, under a desk or whatever else, because it's probably not going to be the glass that falls down but the cornice, some of the ornamental brickwork. who knows. we're likely to get hit by a power line. >> stay in the building. >> stay in the building, get under your desk. keep a bottle of scotch there for -- at all times. i certainly do. >> [laughter.] >> any other thoughts or questions? >> so any final questions? >> can you -- having a foil in between? >> with a foil? between? >> yeah. when you have two glass plates, you put the foil in between so it wouldn't fall down. >> yes, you're right. so a lot of times, we do tempered glass on both sides, and plastic lamination, or whatever, in between. actually, what we prefer to do

is -- i put heat strengthened glass, which we haven't really talked about, and tempered on the other side. heat strengthened glass is glass that is kind of tempered. you know, it's tempered, but not fully tempered. it's got kind of a half measure. stronger than eneeled glass and will take more impact. but where we saw the big piece of glass broken into shards the heat strengthened glass will break into shards maybe this size. the tempered glass, as you see, broke into teeny pieces. so if both sides were tempered and it broke, you know, this whole thing would peel -- you know, would fall over, you know, with this plastic in between, if it didn't have the century guard that -- the new depont stuff which is going to keep it rigid. but if we used heat strengthened on one side and tempered on the

other, the two will still remain rigid. >> i want to thank you all for coming. i want to thank ken paige for this extremely exciting and illuminating adventure today in glazing. and invite you all to come next month when we talk about how to plan a home remodel, and thank you all very much. >> thank you for coming. >> [applause.]