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Building code requirements can present a unique quandary to the introduction of fundamentally innovative techniques and methods in masonry construction.
A discussion of building code and innovative masonry construction begins by describing the alphabet soup of government and industry organizations involved in developing and commenting on this code. Here are some of the major players in developing building code for masonry construction, both in the US and internationally:
ASTM (ASTMI): American Society for Testing and Materials (International)
TMS: The Masonry Society
NCMA: National Concrete Masonry Association
ACI: American Concrete Institute
The requirements for concrete masonry units (block) are described in “ASTM C90 - 11a Standard Specificationfor Loadbearing Concrete Masonry Units.” This document has evolved over the years, and is changed as industry and uses change. It is written by committee members composed of ACI members. This document is commented in a document produced by NCMA simply titled “NCMA Commentary Discussions to ASTM C90.”
The first difficulty lies in finding a proper classification for the block system I have developed. Is it loadbearing or non-loadbearing? According to ASTM et al, if a structure does not support anything other than its own weight, it is non-loadbearing. Since my block system supports only itself, it is technically a non-loadbearing structure. This is of course untrue, since “only itself” includes a dome or arched roof, which means that it is loadbearing.
Another difficulty lays in the fact that concrete masonry units have become standardized to such an extent that there is no allowance for a triangular-shaped masonry unit. All masonry units are assumed to be rectangular, and are even illustrated as such within the code specification.
This rectangular bias, or prejudice, or way of assessing masonry creates a number of difficulties relative to triangular block. Unit strength, cracking, density, appearance, water resistance (absorption), and thermal & acoustic insulation are all affected by whether or not the masonry unit is rectangular or triangular. Fortunately, triangular block which are used to assemble into a sphere, or dome or arch are stronger, less crack prone, more water resistant; and may be made more or less dense depending on wall thickness – thus effecting insulation properties also.
Ultimately, the code is written in such a way to allow for the designer and builder to exercise their own expertise, experience, and professional judgment in their projects. It remains a question whether or not the existing code could be modified to describe triangular block used to build spheres, domes, arches, cylinders, etc., or if a whole new section would have to be added. I am reminded of how much I love to sit on committees.
