# Max.length of 3 meter unbuttresed double-brick wall ?

• posted on November 16, 2007, 4:59 am
Here is S.Africa, where they had a burglary over a 1 meter high wall, they have highened the wall to 3 m. with old-used [but good quality] bricks which they had lying around.
I have heard of free-standing walls collapsing and killing persons, eg. in a storm.
Apparently free-standing walls should have 'posts' built from eg. 4-bricks at specified intervals ?
Since the government building inspection department is probably non-functional since the recent 'liberation take over', I'd like some international advice.
The bricks are British imperial sized: 75x 110x 230 mm. The wall is double bricked, with 'cross-layed' at the top.
Thanks for any input,
==Chris Glur.
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• posted on November 16, 2007, 1:20 pm
On Nov 15, 11:59 pm, problems@gmail wrote:

Foundation / footing and reinforcing are important in wall stability. An engineer is needed to calculate stability. T
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• posted on November 16, 2007, 1:22 pm

It happens.

"Pilasters."
I recently had to convince a client that this was a concern for an interior wall he did not want to reinforce with steel. If you had a wall fall on you, I'm sure you'd rather it was a gypsum partition.
Another variable to consider is the straight length of the masonry wall. Walls with jogs, spaced closely enough, buttress themselves. (Our code here calls for intersecting walls or buttresses (pilasters) at no more than 36x the wall thickness for non-loadbearing walls.) There is the precedent of the traditional serpentine wall to consider, too, and which deals with the problem of overturning and wall slenderness:
http://commons.wikimedia.org/wiki/Image:Serpentine_wall.jpg
At 3m high and presumably 230 thickness you are at 13x thickness which is a bit higher than my engineer would permit...If you are concerned, you should have a pro look at it, or stay away from it, especially in a good wind or if people are operating vehicles near it.
--

MichaelB
www.michaelbulatovich.ca
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• posted on November 16, 2007, 2:05 pm
Michael Bulatovich wrote:

I was going to reference him to the serpentine wall at the St. Louis, MO, Zoo. It's tall, but wavy to keep it standing up...
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• posted on November 16, 2007, 2:58 pm

Sure you were. ;)
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• posted on November 17, 2007, 11:31 am

The UK codes have something similar - can't remember the ratio, 25 years since I last had to use it - but that code didn't have seismic requirements, or much in the way of wind-loading for free-standing, as I recall.
Avoidance of pilasters would require some form of reinforced bond beam coping, maybe post-tensioned rods, foundation to coping at ?? spacing. Easier to do it in hollow masonry block. Keep the bricks for decorative paving. Or crush into pea-gravel for the same purpose :-)

Once saw an example of something like this - free-standing wall at the side of a fire station. The wall was post-tensioned, eg threaded rods from top to foundation. A fire truck is capable of packing a punch ...