ORPHANAGE JOB

So what’s the difference between a class B block and the typical concrete block available at a local lumberyard or home store? It comes down to the required thickness of the walls and the size of the hollow core. Blocks purchased at home repair and maintenance stores typically have large hollow cores and are not adequate in thickness or density for fire resistance.

So how does an inspector know if the block being used is of the correct classification? The construction design will indicate a required classification. Additionally, block shipments usually contain a certificate with its classification and inspectors should ask to see that certificate.

1. Block classification should be checked routinely and automatically. There are also various issues to consider before application such as the type of mortar used, how to keep the mortar from freezing, what accessories will be used and the bearing conditions and penetrations. All of these components comprise an assembly.
2. Indeed, masonry construction is solid and serves the construction industry well. And to make my brick mason friend happy, I will concede that it is almost “forever.” However, as with other types of construction, masonry too, is subject to inspection and must also comply with applicable codes and standards. Early in my career, I worked with a brick mason who declared “masonry construction is forever.” In a humorous response, I teased him saying he’d spent too much time carrying mortar up a ladder. But actually I knew when properly installed, masonry really is solid; it serves the construction industry well and provides outstanding protection against the spread of fire. Given its tested reputation, many inspectors have developed a mindset that keeps them understanding that because masonry is fire-rated it needs no inspection, or that all 8-inch block has a two-hour fire rating.
3. Consider the common misconception that all concrete block has a rating. If you look at the UL Fire Resistance Directory, it shows the block used in a fire-rated assembly must meet certain requirements. A 2-hour firewall requires a class “B” block. The block alone must be constructed following certain specifications. Its fire resistance rating is based on the thickness of the block.

So what’s the difference between a class B block and the typical concrete block available at a local lumberyard or home store? It comes down to the required thickness of the walls and the size of the hollow core. Blocks purchased at home repair and maintenance stores typically have large hollow cores and are not adequate in thickness or density for fire resistance.

So how does an inspector know if the block being used is of the correct classification? The construction design will indicate a required classification. Additionally, block shipments usually contain a certificate with its classification and inspectors should ask to see that certificate.

Block classification should be checked routinely and automatically. There are also various issues to consider before application such as the type of mortar used, how to keep the mortar from freezing, what accessories will be used and the bearing conditions and penetrations. All of these components comprise an assembly.

Indeed, masonry construction is solid and serves the construction industry well. And to make my brick mason friend happy, I will concede that it is almost “forever.” However, as with other types of construction, masonry too, is subject to inspection and must also comply with applicable codes and standards.