Home & Garden Columns

About the House: Through a Glass Sharply

By Matt Cantor
Friday September 07, 2007

Everybody has a little internal list of least favorite ways to die. Some of these are rational, but mostly they’re derived from some fantasy, childhood experience or errant datum we’ve chanced upon. Perhaps we were children and heard an awful story. Maybe we encountered saw someone killed in a movie—lots of those, aren’t there?! Perhaps it was simply a story related by a friend. Regardless of the source we all have these.  

I think these fears extend into injuries as well and not just to the finality of death. I know that, for myself, certain kinds of sickness are nearly unbearable while others, and these may be the dread of another, are sort of no big deal. For example (am I grossing you out yet?) I have little fear of bleeding, having cut myself about a thousand times and sometimes rather severely. It might be a carpenter thing. Those of us who have built houses and handled tools are fairly accustomed to sucking our own blood while we wait for a promised coagulation. 

While I do not fear a death by blood loss nearly so much as numerous other fates, I am much aware that it is a common way to leave the humanosphere. In the late 1970’s deaths caused by glass lacerations were so common that the Consumer Product Safety Commission created a series of heavy guidelines that continue and grow today.  

What was happening was mostly one of two things. People were either walking through glass patio doors (OW!!) or striking and breaking shower doors or enclosures (OW again!). Blood loss can kill you in minutes if the damage is sufficient. The carotid (neck) or femoral (leg) arteries, when sliced, can bleed out in five minutes. Basically this means that you simply do not have the time to get adequate medical help. Again, sorry. This is so awful to discuss but I’m sure you’ll agree it’s important; mostly because there are real answers and valuable actions that CAN be taken. 

The glass industry, much aware of these issues (who gets sued, after all?) began in the early 1960s to produce shower and patio doors of a relatively new material called tempered glass. The easiest way to think of tempering is to visualize a vandalized car. Those funny little squarish pebbles of glass that litter the ground are the remains of tempered glass. Tempered glass, invented by the Austrian chemist, Rudolph Seiden (b.1900), is made by heating one side of a sheet of heat-strengthened glass to a higher temperature than the other and then cooling it very rapidly. This creates a tension between the two faces of glass that forces it to crack perpendicular to the plane of the glass, rather than in sharp shards that can cut through my sensitive and incredibly important body. Breaking perpendicular to the surface of the glass creates little squarish pebbles and, while these may cause abrasion, will spare us the nastier experience when we strike and break a sheet of glass. Danke schön, Herr Seiden! 

Let’s talk about patio sliding glass doors just a bit. I feel as though the greatest danger with these is where there is a distant objective that acts as an incentive to speed. Let’s say you have a swimming pool surrounded by happy people and clam dip twenty feet from the door and a good twelve or fourteen feet of room to cross toward the door leading to the pool. Now, let’s say that the door is clean and there’s nothing to alert one to the presence of the glass. You might, as many before you have done, assume that door is open. You see, it looks almost the same open or closed if the glass is clean. You might then be walking at 5 mph by the time you hit the glass. Some just walk right through and this, of course, it usually tragic. 

If you have a non-tempered sliding glass door please consider replacing it with a new one. These days you can’t buy anything BUT tempered glass doors unless you buy something used. If you’re really strapped for funds, there are two alternatives. The first is to put a safety film on the glass. These films are commonly available and help limit the nature of the breakage. The film is essentially a sheet of strong sticky plastic that holds the shards of glass together and prevents deep laceration. A very cheap alternative is to put stickers on the glass door so as to alert the potential victim to the fact that the door is present. This is a better but bad choice (all you parent know about these choices, right?). The point is that any action is better than none but given the concern level, replacement is the wise choice. 

So how do you know if you have a non-tempered glass door? Tempered glass nearly always bears a tempering mark or “bug” in one corner of the glass, usually at the bottom. The mark is sort of a glass tattoo, heat fused onto the glass and somewhat translucent. You may have to wash the door to find the mark. Well, HAVE you washed the sliding glass door in the last five years? If the door has no discernable mark, it is extremely likely that this door is low strength glass and dangerous. By the way, these same marks are used on all forms of tempered glass and you’ll recognize them as being similar to the ones seen on your car windows. 

Aside from breaking in such a mannerly and genteel fashion, tempered glass is also less likely to break at all, being roughly 4-6 times the strength of common glass. Laminated glass is another form of safety glass but less desirable than tempered due to the fact that it will still crack sharply and grab little flaps of skin (sorry) as one bounces off the plastic-reinforced sheet. Wired safety glass is a much older form and again, while safer than common float glass, can still do tremendous harm when compared with our beloved tempered glass. 

Shower doors are another major concern and have been the subject of the building codes for about 30 years. While no one is making anyone remove older ones, it has been impossible to buy a new untempered shower door or enclosure since the 1970s. Again, tempered ones have been available since the early 60’s but enforcement has taken time to catch up with manufacturer wisdom. What all this means is that you may still have a shower enclosure that can kill or injure someone who does nothing more malicious than swing around, elbows out, and smack the door.  

Today, none of the glass in a bathing area below 5’ and none of the glass in either an enclosure or a shower door may be non-safety type. This includes windows in the shower or bathing area as well as mirrors. Some special exceptions are made for art glass. 

The more we learn about the danger of glass in our houses, the more extensive the list of uses or places where we want to use safety glass grows. Here are a few of the other places we want to be looking out for: 

Windows that nearly reach the ground are vulnerable to kicking, rolling objects and children at play. Most codes today demand that where glass is within 18” of the ground, it should be tempered.  

Where glass is in any kind of door, including those multi-lite “French” doors, it should also be tempered. Again, unless you buy an old used door, you just can’t find a non-tempered “French” door. Nobody makes ‘em. 

Glass that is within about two feet of a door (sidelites) should be tempered due to the shock of a slammed door. Many a marital dispute has ended with the crash of such a window (followed by that most absurd of proclamations, “See what you made me do?”). 

Mirrored sliding closet doors (how I hate having to see myself that much) are not required to be tempered in most communities but must be adhered to a backing that prevents those nasty pieces from coming free. Nonetheless, you can buy these in tempered glass and this gets my vote. 

These are the traditional areas that we in the home inspection business have been looking at for decades- but wait, there’s more! Now the building codes are asking us to look at all glass in the walking path. If you can walk within three feet of any large glass pane (>9 s.f.) that is close to floor level (>18”) and at least three feet high, the new codes are asking that this be make of tempered safety glass. My guess is that we’re just a few years away from ALL of our windows being made of safety glass. It may seem like a pain but in the long run, we’ll look back in disbelief that we ever lived so blithely with such treachery. 

The code is also speaking to glass used in railings as well and thank Buddha! What crazier place than a stair railing might you use glass? Actually, I think glass is very cool and love it in all these odd places but I feel a lot better about that platform-heeled mom in short-shorts and a tee as she walks down the glassed-in stairway knowing that when the worst case occurs and she losses her footing, that the paramedics will spend most of their time complimenting her voluntary piercings and no time treating the involuntary ones.