If you’ve worked with wood at all, you know that as great and versatile as it is, it’s generally not the hardest material in the world. When you hammer a nail into a spruce framing member, you can easily drive it beyond the surface of the wood, even if it’s a big framing nail. When you drive a screw into the same wood, you can countersink it without pre-drilling.
Which brings us to bolts. Often, you need to use bolts when attaching framing members – to a sill, to a wall, to each other. What’s going to happen to the bolt as you continue to tighten the nut? Well, it’s going to sink into the wood, just like the nail and the screw.
Fortunately, there’s a simple solution: washers. No namby pamby little washers, either. The force of the bolt must be spread out over as large an area as possible – within reason. With smaller washers, the fibers get crushed before the bolt’s tight enough to hold the two pieces together. So use a larger washer, maybe three times the diameter of the bolt’s head.