Someone recently asked me, “What is CPTED?”
CPTED (pronounced sep-ted) stands for Crime Prevention Through Environmental Design, and is defined as “a multi-disciplinary approach to deterring criminal behavior through environmental design.” The concept is that by incorporating certain design elements or modifications, we can influence a potential offender before a criminal act takes place. For example, increasing exterior lighting and reducing landscaping that could conceal an intruder may discourage attempts for unauthorized entry to a building.
CPTED strategies can be useful in any type of facility, and there are numerous training programs and resource materials available. Given the current focus on school security, some of the materials are specific to educational facilities. The concepts used in CPTED are valuable for analyzing schools, and there are often simple changes that can be made to reduce the likelihood of an intruder entering the building. Some of these concepts may seem like common sense, but it’s all about balance – providing a safe environment without negatively impacting the educational experience.
There is an article by Brad Spicer in Campus Safety Magazine called 11 Components of a Secure School Front Entrance, which includes some good ideas about implementing CPTED for the front entrance doors in a school. I like that he mentioned the use of mullions (although a mullion often sits behind the doors rather than “between double doors” as the article states). I’m not sure, though, about the recommendation for door pulls and push bars to be flush with the door to prevent them from being tied together. I agree that it’s important to avoid that if possible, but the ADA Guide recommends 1 1/2 inches of clearance behind door pulls, creating a conflict between accessibility and security.
Check out the article and leave a comment below if you have any CPTED-related ideas to add, particularly regarding the door pull issue (we talked about it a while back).
Photo: Special-Lite FRP pair, posted with permission from Chris Mayer of Mayer Door.
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This article, about passively deterring unwanted behavior through architectural design, reminded me about a related subject, hostile architecture: architectural design to passively drive away the homeless. Things like small metal spikes to stop the homeless from sleeping in front of entrances, park benches designed to be impossible to lay on, artwork and architectural detail meant only to fill space that could be occupied by the homeless. It’s the same concept as the passive security in this article: using social engineering via architectural detail to discourage behavior the building owner/manager doesn’t want. But on the other hand it turns our urban environment into an inherently human-unfriendly space, so that only people engaged in “economically useful activity” can freely use the space.
I was interested in how you feel about this type of design? Maybe you could do an article or blog post on it.
Hi Michael –
Honestly, I have not looked into that issue, other than discussions with architects about whether to lock the inside or outside doors on vestibules in areas where people may enter a vestibule through an unlocked exterior door and seek shelter in the vestibule. I’ll put it on my list and read up on the topic.
– Lori
I am an architect and work primarily on schools and my preference is to have the front door unlocked and the vestibule door locked, but both options can work. I think allowing people into the vestibule gets the average parent inside and out of the weather where they can take off their hood and be seen by the admin staff. From there they can be buzzed in or speak through an intercom before being allowed into the admin space. But even once they are in the admin the door into the school is also typically locked as a second means of control.
I think he was more referring to a fixed center mullion that more of treats the opening as two individual doors in one frame. At least that is the way I read it.
You could definitely do a fixed center mullion, but a removable mullion is more common and allows the full width of the opening to be used to move furniture, etc. through.
– Lori
But to get the visual deterrent (I think he is talking about on the exterior) the fixed mullion would be the way to go.
Do you think seeing a mullion between the doors, vs. seeing a pair with the mullion hidden behind them, would be a visual deterrent?
– Lori
I think it could show a more “beefy” opening to someone who doesn’t know doors and frames. Plus if you add some through bolts into the hardware I think that could also potentially be a deterrent. They may not know what is keeping it shut but shows that there is a footprint of something (especially for 2 and 3 point latching panics). The way I see it is if the more you show the more likely it is that they will think that opening isn’t worth the hassle. Criminals want an easy in & out and if you make it look hard the more likely they will try somewhere else. But that is just my thought on it.
Actually, CPTED historically did not involved hardware. The concept goes back to the 60’s; but it’s was not until the a criminologist named Tim Crowe in his book “Crime Prevention Though Environmental Design” (not to be confused with C Ray Jeffery’s book of the same name), that the concept was popularized (I know because I was there with all these guys) and incorporated into the national crime prevention narrative: “….The proper design and effective use of the built environment can lead to a reduction in the fear of crime and the incidence of crime, and to improvement in the quality of life.” The basic assumption of this theory is that the arrangement of buildings and/or the internal and exterior spatial relationships can either encourage or discourage crime. CPTED then, extols prevention of crime as byproduct of good design. Its original guiding principles included natural access control, natural surveillance and territorial reinforcement. Later on, “proper use and maintenance” of space was added as a fourth principal. In most of the literature supporting CPTED you will find little about door hardware and technology (more often considered as “traditional target hardening” strategies); rather, physical security strategies are used to support CPTED. The example I often cite is an exit alarm or delayed egress device that forces entrants to a more highly surveilled entry point. BUT, if good CPTED practice is actually incorporated in the design, the use of locks, guards and technology measures can be minimized.
I can give you thousands of examples of this design motif at work, but my point is that it has little to do with hardware and everything to do with design and use of a space. Properly implemented, it can cut cost, promote customer flow and enhance the occupant experience.
We recommend a door pull on only **one** leaf of a pair of doors to “prevent them from being tied together”. Around these parts, pranksters and vandals will place a stick through the two pulls to keep the doors from opening. A center mullion with single point rim panics is much preferred to the pricey PIA vertical rod devices which we avoid whenever possible.
Pulls:
My go-to accessible flush pull: the Trimco 1111C.
Surface pulls, I suppose, could be fastened with thrubolts designed to break at, say, several hundred pounds, knowing that the locking device latchbolts will fail at a much higher value. Haven’t actually specified such an item; if CPTED has guidelines for break-off fastener design, then it seems that we have a solution.
CPTED does not include hardware solutions like this because its not within its scope of the principle. CPTED is about the relationship of space and its impact on criminal and occupant behavior.
The best solution to address the door lockin issue (using standard hardware trim) in my view is having only one pull on the active leaf of a pair. That said, architects don’t like the unbalanced look of the door and its up to us to persuade differently.
Tom’s suggestion called “engineered weakness” is something Allegion has done before (that clutch mechanism on the vandal resistant lever trim). Lori, take that up with your engineers. How about a pull that will come apart, but will not be engaged until the interior bar is depressed?
Great long needed attention to this topic. I was introduced to cpted thru crime prevention organizations in the 80’s. Double pulls create poor function and hazardous situations. The alternatives suggested here are enlightening and helpful.