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[Link: icc-es.org]

Guys, remember there are at least two different kinds of building blocks in use. There are concrete blocks, sometimes erroneously called cinder blocks but these are made of concrete and are quite hard and strong. They are used where strength is needed or exposure to the weather and are often used in 8 to 12 inch thicknesses, however they are available down to 4 inch thicknesses, so check which ones are used before mounting heavy items.

Secondly there are light weight blocks, could be made with cinders as they were originally, often from coal powered boilers. Now they may be made with other light weight materials that are available locally, which could be cinders, steel mill slag or light aggegate. These are not very strong and are used for sound and/or fire separation, not structural, often between office or housing units, and only when not exposed to the weather. Be carefull when mounting on these as they cannot carry the same weight as genuine concrete blocks and often use thin blocks giving a wall 4 to 6 inch thickness.

Before mounting anything on a block wall it pays to know the thickness of the blocks and the type of material they are made of, otherwise you could have a failure with the item falling off or even the wall collapsing.