Johannesburg - High walls around your house attract criminals.
This was the basic message from leading criminologist Monique Marks, who was asked for comment after News24 compared the height of walls around some houses in Durban, Cape Town and Johannesburg to those of prison walls.
The Department of Correctional Services deputy commissioner for incarceration, James Smalberger, told News24 the perimeter security fence at maximum security facilities "is normally five metres or higher with the same applying to the actual wall itself".
Some of the walls News24 found were comparable to the heights Smalberger had indicated.
Marks, a criminology professor at the Urban Futures Centre at the Durban University of Technology, and Durban metro police officer Chris Overall conducted research last year to establish if high walls actually generated greater security.
In short, the answer was "no".
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"I don't think people understand. They've created their own sort of fortresses which really have imprisoned them in a very unsafe space," Marks said.
"People who are going to conduct organised crime don't want to be seen, because they need time to do these kind of things, which is why you find the more serious kinds of armed robberies and hijackings tend to take place behind walls."
For serious crimes to be committed in view of the street was "very, very different and very difficult".
Having a low wall allowed for increased visibility or "natural surveillance" from the street.
"What high solid walls do is prevent visibility, both from inside out and outside in. You have people patrolling your streets, the police or private security and something is going on, they can't see in and you can't see out," she said.
"That's very frustrating for the police. Often people say 'We pay private security companies and they tell us they never know what's happening'. It's because they can't see inside."
Marks said the ideal boundary structure would be palisade fencing or fairly low walls so you can see in and out.
Psychology of fear
Pam Golding Properties business executive Trish Luthuli said high walls could enhance the value of a home.
"Many residents value walls even if they live in one of the many popular Gauteng estates that have their own boundary walls or fences," she said.
However, Marks said high walls also created mental walls in the minds of those living behind them.
"Basically, I'm defending myself against you on the street. You on the street are a problem, I don't want you in my space," she said.
"I think that generates a psychology of fear both for the person on the inside and for the person on the outside, but also a sense of possible animosity from people on the street who are constantly confronting these defensive structures."
City of Joburg mayor Parks Tau lamented high walls around houses in an interview with News24 earlier this year.
"Sometimes the things we do that are intended to secure us cause greater harm, because we build high walls that enclose people from their neighbours, so people are unable to see through the rest of the suburb and that impacts on the suburb," Tau said at the time.
In Cape Town, there are bylaws specifying no solid wall could be higher than 1.8 metres on the street and palisade fencing 2.1 metres. Also, street boundaries, including the gate, must have a 40% visible permeability.