Bolt spacing and edge distance chart

Reading it

• —NDS geometry requirements for full design value — the standard the building code references rather than the code itself. Defaults, not law: ring the building department, and get anything holding a structure up designed by somebody who will stamp it.
• —End distance is along the grain and edge distance is across it. The gap between the first two columns is the useful one: a tension joint tries to split a plug out of the end of the board and a compression joint does not, so turning a connection around nearly halves the room it needs.
• —Everything scales with the bolt rather than with the timber. A wider board does not make a bolt near its end any safer.
• —Reduced spacings are permitted at a proportionally reduced design value and are deliberately not printed here, because that is a decision with a load behind it rather than a number to read off a chart.
• —The hole is a sixteenth over the bolt — enough that it goes through two parts whose holes never quite line up, and no more, because the slop is movement before the joint takes load. A lag is different: its threads cut their own way and want a pilot hole smaller than the shank.