Annealed Vs Tempered Vs Laminated Glass Differences

Different Types of Glass Used in Replacement

This our broken annealed plate glass. Notice the sharp glass shards.

This article is an extension of A Basic Guide to Glass & Glazing. We will try to explain to you differences and the various uses for laminated, tempered, and annealed glass for residential and commercial glazing.

Annealed Plate Glass

This is today’s cleanup :(. We received bad delivery. This glass is called annealed plate glass. Annealed glass gets its name from the process by which it is made- the Annealing Process. The glass is heated above its “annealing point” of 600 degrees and then is cooled at a very slow and controlled rate. Annealed glass, unlike laminated or tempered safety glass,  breaks into sharp glass shards that can have devastating results if improperly installed. Annealed glass has the potential to free fall and cut in a similar fashion of a guillotine.

Glass Cost-

Annealed glass is cost effective in comparison to both laminated and tempered glass (see below).

When to use Plate Glass?

Annealed glass is priced a lot cheaper than both tempered and laminated glass, but it’s use does come with various concerns, codes, and regulations. State Regulation and building code forbids annealed glass to be installed in bathrooms, doors, and door lites (the glass adjacent to the door.) Also it is illegal to use plate glass if the glass is larger than 9 Sq Ft. Annealed glass is commonly found in single, double pane & triple pane windows as well as old cabinets and tabletops. Annealed plate glass is a great option when used in a low-traffic area, where safety is not a major concern.

Safety Glass

State & Federal law as well as building code regulation requires safety glass when replacing door glass, door glass lites, bathroom windows, shower glass, furniture glass and any piece of glass over 9 sq ft. Federal regulation requires all auto glass to have safety glass. Annealed plate glass is not allowed in vehicles.  The two main types of safety glass are laminated glass and tempered glass.

This is a common charictoristic of broken tempered glass- they break into small dull popcorn-like pieces.

Tempered Glass

Tempered glass, also referred as “toughened glass,” is plate glass that goes through a special heat & cooling treatment to toughen the glass. The annealed plate glass usually is heated to 1110 degrees farinheight then is cooled on the outer surfaces. The cooling pattern causes the outer surfaces to contract faster than the center thus giving the tempered glass its strength.
Tempered glass is considered safety glass because it shatters in a unique way that prevents harm. You can see broken glass with the picture on the left.  The glass often shatters or ‘explodes’ into many tiny and dull pieces.

When to Use Tempered Glass

Tempered glass can withstand 5-7 times the amount of pressure than plate glass, thus it is best used when safety is of concern. Tempered glass can quickly and safely shatter when a  situations arises where one has to either escape or be rescued from harm. Tempered glass is choice for high end retailer’s display cases and storefronts because tempered glass can be created from ultra-clear low-iron glass. Unfortunately glass that has been tempered cannot be cut, therefore it is unwise to choose tempered glass when a non-professional measures the glass. The tempering process generally takes 6-10 business days as the  wait time is contingent on how busy the tempering facilities are. We recommend laminated-safety glass when time is of essence.

This is what storefront laminated glass looks like after somebody tried to break in. The glass maintained its structure, and the thief was not able to get in.

Laminated Glass

Laminated glass is a type of safety glass. Rather than shattering like tempered glass, laminated glass maintains its integrity after breaks. Laminated glass is basically a sandwich. It has two sides of glass that sandwiches vinyl- either polyvinyl butyral (PVB) or ethylene-vinyl acetate (EVA). The laminated unit can be made of either annealed or tempered glass.

When to use laminated glass

Laminated Glass maintains its integrity when blunt force is used against it therefore s is great solution when break-in security is a major concern. Examples of laminated glass include storefront doors, windows, and display cases. All windshields are, by law, laminated glass- this prevents shards of glass flying into the car when objects hits the windshield.

See Also:

• Tempered Glass Vs. Laminated Glass
• Common Glazing Terminology
• Common Window Problems
• Servicing Areas

Additional information :

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