OK, I give up…what is it? One of our clients is asking for “Riot Glass”. Is this, as I suspect, just a slang term, and if so, what does it mean? Bullet resistant? Blast? Lexan?
Any one heard of or used riot glass?
“Riot Glass” is a slang term for laminated glass.
I have just done some research on security glass. There are different tests available for attack resistance, forced entry resistance and ballistics resistance. Assuming that ballistics is not the issue, check out H. P. White Laboratory’s test procedure HPW-TP-0500.03 (available on their website www.hpwhite.com), and ASTM F1233 Standard Test Method for Security Glazing Methods and Systems. Both of these standards include a sequence of physical attacks using various tools. The glazing is then classified according to number of attack sequences the glass is capable of resisting. Reviewing the web sites of some glass fabricators, it appears that some relatively thin laminated glass products would meet the lowest grade of attack resistance. However, I don’t know the specific composition of those assemblies (yet, I’m not done with my homework), but I would not assume that ordinary nominal 1/4 inch lami would do the job. I would suggest that you need to get much more specific direction from your client about their expectations.
John makes a good point: The design team needs to counsel the owner in the wide variety of tests, and the corresponding plethora of products out there that meets those various requirements. The Architect cannot possibly decide on which product is best suited for a certain application without first having some “expectation criteria” from the Owner: WHAT THREAT LEVEL ARE THEY TRYING TO STOP?. I feel the Owner has some obligation to reveal, or at least provide some sort of minimum base line regarding what threat level to which the Architect needs to design.
If an Owner merely asks for “bullet-proof”* glass for a pharmacy window, the Architect - assuming they consult UL 752 - is faced with the prospect of 8+ rating levels. Absent any input from the Owner, which one do they select to design to?
- Correct term is Ballistics Resistant
The required level of protection may in some cases be dictated by the owner’s insurance carrier.
For this kind of “stuff”, getting owners to tell you what standard to design to is difficult. Getting familiar with the standards and products can help direct the conversation, but it will still be kinda dicey.
Typical laminate glass construction uses 30-mil PVB. There is UL 972 “Standard for Burglary Resisting Glazing Material” that requires a 60-mil PVB interlayer. It prevents “smash-n-grap” type attacks and is not intended to be ballistic resistant.
I was in on a discussion about bullet-resistant construction where a specialty glass fabricator suggested in the absence of other guide lines from the owner, the Architect should inquire about what firearms the owner’s security officers are carrying. Choose ballistic-resistant products that resist bullets from that firearm.
The thinking is that the weapon most often discharged in that environment will be the security officer’s weapon (shots fired by officer with his/her weapon, shots fired by someone who has taken the weapon, or accidental discharge). Feds require UL Level 3 (tested to resist shos fired with a .44 magnum handgun); I would hazard a guess that UL Level 2 (.357 magnum handgun) would be adequate in most settings (not a professional recommendation).
I generally design to “high powered small arms” (UL level 3) if there is no specific design criteria from the Owner, although I advise them that this selection is preliminary and subject to their carrier’s approval. in urban hospitals, we are designing for automatic long guns, and I forget what level that actually is.
also: remember that if the glazing is ballistics resistant, the surrounding walls and ceilings must be as well – otherwise, the perpetrator simply jumps on a chair, pushes up the ceiling, and fires down through the ceiling space. In addition if you are designing for impact resistance (like for the WTO riots that were in Seattle five years ago, ) you need frames that can withstand the impact as well. if the glass is going to deflect, which is what laminated glass does, it will need larger frame bites to deflect from and return to.
My orginal question rises from a client rep suggestion to change the outboard lite of some normal IGU (no blast or ballistics required) to “riot glass”. The client is fairly savvy about ballistics and blast requirements, both of which were required with great specificity on other components and assemblies in the project, so it surprised me that a slang term was used in this case.
We have been pushing the client to give us tangible performance criteria, as suggested here, but I suspect that in this case, “riot glass” = “laminated glass” in the mind of the client. Thanks to all for the references and comments, which have been very helpful.
We have an office building project with a curtainwall designed for blast resistance, but the laminated lite is the inner lite of the insulating unit, not the outer lite. The reason is that the outer lite is sacrificial, with the inner laminated lite providing more protection for the building occupants. If the outer lite is laminated, the inner non-laminated lite could still fracture and blow inwards, harming the occupants.