Special Inspections
Some building departments require “special inspections” for the bolts, holddowns, and plywood. These are performed by third party companies. Each special inspection costs $1,000. $650 for the special inspector and $350 to us.
Bolt Inspections:
For the bolts, they usually want to physically watch us tighten 25% of the the bolts with a special socket wrench called a torque wrench, even though we always install them with impact wrenches similar to what mechanics use to tighten bolts on tires. We do this because it is so fast and the bolts are very tight. When we tighten them with a torque wrench they are looser than they could be. Once the special inspector leaves we go back and tighten them properly.
Perhaps the strangest thing about this is that tightness of bolts has zero impact on the sliding resistance of the bolt. 1 month after a house is built all the nuts on the foundation bolts are loose because the mudsill shrinks after it dries. At this point you can remove the nuts by hand. If tight bolts were a serious matter, re-tightening the bolts after the mudsills shrink would be a code requirement.
Types Of Special Inspections
There are two other types of special inspections.
Holddown Inspections: Holddowns requires bolts be placed in holes that are dust free. The special inspector will be checking for dust after we drill the hole in the concrete. The holes we drill are dust free. We use a special bit attached to a vacuum that removes all the dust when we are drilling holes in the concrete. Some building departments require pull tests which only special inspection firms have the equipment to perform.
Plywood Inspections: If plywood nails are spaced less than 4″ apart on the edges another special inspection is required. For these inspections that inspector stares at the nails for 10 seconds and you are billed $1,000. To avoid this expense we install the nails 6″ apart and when the inspector is gone we re-nail the plywood 3″ apart. We do this because a retrofit with nails 3″ apart is twice as strong as a retrofit with nails 6″ apart and 25% stronger than a retrofit with nails 4″ apart. This webpage explains the importance of nail spacing. In other words, we do what we can to prevent the building department from making us do it wrong.
