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Glass Types and Information
There are two kinds of safety glass used on RVs, Motorhomes, and Motorcoaches- Tempered Glass and Laminated Glass.
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(a) Safety Glazing Material. Safety glazing material is any glazing material so constructed, treated, or combined with other materials as to reduce, in comparison with ordinary sheet, plate, or float glass, the likelihood of injury to persons by glazing material whether it may be broken or unbroken.
Federal Motor Vehicle Safety Standard (FMVSS) No. 205, “Glazing materials,” (49 CFR 571.205), specifies performance requirements for the types of glazing that may be installed in motor vehicles. It also specifies the vehicle locations in which the various types of glazing may be installed. The purpose of FMVSS No. 205 is to reduce injuries ( e.g., lacerations) resulting from impact to glazing surfaces, to ensure a necessary degree of transparency in motor vehicle windows for driver visibility, and to minimize the possibility of occupants being thrown through the vehicle windows in collisions. FMVSS No. 205 applies to passenger cars, multipurpose passenger vehicles, trucks, buses, motorcycles, slide-in campers, pickup covers designed to carry persons while in motion and low speed vehicles, and to glazing materials for use in those vehicles.
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This glass is composed of 2 layers of glass (typically annealed/plate glass) with a security layer, PVB (Polyvinyl Butyral) between the panes. PVB is the required interlayer for this automotive/RV application. The panes of glass maybe tempered or heat strengthened in some cases, but isn't required -or- neccessary here.
If either of the glass panes is compromised the (PVB) interlayer keeps the glass together- so glass is less likely to break free and hurt anyone. Laminated glass is required for windshield applications.
Laminated glass can be used in most side window and windshield applications. Windshield and window glass used for the operation of the vehicle are held to glass color and tint guidelines though. This is why you can see the dark privacy glass 'windshields' on towable RVs, yet on any motorhome/motorcoach they are solar/green or clear.
Laminated glass can be built into double pane glass units, as well as take the place of double pane glass units if the proper thickness is used to match the thickness of the double pane glass. You can click here to learn more information about laminated glass units.
Laminated glass shouldn't be used in shower enclosures though. Being that laminated glass is typically constructed with plate glass, the glass cant withstand the stress around the hardware contact points for shower enclosures.
Laminated Info
Tempered Glass
Tempered glass is plate glass which is super-heated for a brief amount of time, then rapidly cooled 'quenched' to harden it. Tempered glass is 4-6x stronger than plate glass, being able to handle stress and impact- it is commonly used in automotive applications. If tempered glass does break it shatters into small pieces. These small pieces are not able to critically hurt anyone. This being the case, all fabrication (cutting, drilling, and grinding) must happen to the plate glass before it is tempered. Some minor polishing can be done to the edges and surface of tempered glass, but that is about it. If too much of the suface is removed (cut or grinded on) the entire glass shatters at once.
Tempered glass can withstand a great amout of surface impact. It takes a lot of pressure in a small area on the surface for it to shatter (i.e. the most common reason is a rock getting thrown from a lawn mower). However, the 'Achilles Heel' of tempered glass are the corners and edges. If the edge or corner of tempered glass receive impact from a hard object, it is most likely that the glass pane will shatter. This makes the newer frame-less windows extremely vulnerable.
Tempered glass isn't used in windshield applications because not only would the glass shatter all at once (instead of cracking), completely obstructing the view of the operator. If the tempered glass wasn't also laminated, it would end up all over the cabin/cockpit, operator, and passengers. This is why lamianted plate glass is best for most windshield applications.
Tempered Glass
Glass Values
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