Why does substrate matter?
To determine the strength of a fastener before withdrawal will occur, we need to know what the fastener will be embedded into. The PSI of concrete tells us the density of the concrete. In turn, we can determine how much withdrawal the fastener can resist. The higher the PSI, the higher the withdrawal capacity.
Similar to the concrete, wood density can be measured by using the specific gravity. Specific gravity can typically be determined by what the species of lumber is. Again, higher specific gravity results in higher withdrawal capacity.
Of course, concrete is typically far more dense than wood, which is why we generally see larger wood fasteners required than concrete anchors.
NOTE: WE DO HAVE A PRE-CALCULATED LIST OF SPANS/FASTENERS FOR SPECIFIC SUBSTRATES THAT WILL WORK IN MOST SCENARIOS. IT IS IN EVERYONES BEST INTEREST TO SUGGEST THAT A BUILDER USES HIGH PSI CONCRETE, OR HIGH SPECIFIC GRAVITY BLOCKING MATERIAL, ESPECIALLY WHEN CALCULATIONS ARE GOING TO BE REQUIRED!!!