I installed a sliding window in my home in Minneapolis and the inspector failed it saying it's not tempered glass. How can I tell if it’s tempered based on the stamp?

Here’s the code info from the stamp:

Quality Control & Testing
Series: 7400 HS
Accredited by
LCP000-2756x1538 (109.61)+S
American National Standards Institute
R-PC20-1829x1829 (12x72)HS.
Validator: ALI®
MFR Code: TTW-1
RPG40-1829x1219(72448)+S (INS. TEMP CL)
This product rated in accordance with NERC 100 400-008

  • Is this window above the tub or shower? (And if yes, is it less than 60” from the drain?) Mar 10 at 1:55
  • Does it have the 16 CFR 1201 markings on it? If not, it is not compliant safety glass, even if it is tempered Mar 10 at 4:31
  • Just about every tempered door and window I've installed has been clearly labeled TEMPERED.
    – isherwood
    Mar 10 at 14:25
  • Look at sunlight though the glass using polarizing sunglasses. Google for examples of what it will look like if it's tempered.
    – Ariel
    Mar 10 at 21:17

1 Answer 1


The glazing is required if it’s within 24” of a door edge (jamb) and it’s required if all of the following items are met: it’s greater than 9 square feet, bottom edge is less than 18” from floor, top edge is greater than 36” above floor, AND a walking surface within 36” horizontally of the plane of the glazing. (See Section 2406.3.7)

There are installations where safety glass is not required, but I don’t see any that apply in your case: around swimming pools, stairways, etc.

If the glazing is required to be safety glass it can be plastic, laminated or safety and shall meet CPSC 16 CFR Part 1201 “Safety Standard for Architectural Glazing Materials”. You can contact the following agency to get your question answered and verify you have approved safety glazing:

Consumer Product Safety Commission
4330 East West Highway
Bethesda, MD 20814-4408

  • you seem to be answering a different question.
    – Jasen
    Mar 12 at 0:30
  • 1
    @Jasen The first part outlines if tempered glass is even required. The second part of the answer gives you a place to go who can interpret the code and let you know if it’s tempered, as the inspector requires.
    – Lee Sam
    Mar 12 at 4:23

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