- There are essentially two different types of anchor bolts: J bolts and friction anchors. J bolts have a hook on the end that resembles a j. The hook can be hooked around a piece of rebar or just seated into wet concrete. A friction anchor has a ring around its bottom that is pulled tight by the pressure of the tightened bolt and held in place in a hole in the concrete foundation. You can also set a friction anchor into epoxy. You will need a hammer drill and a 1/2-inch concrete bit for installing the friction anchor. Optional materials include epoxy, a thumb wrench and a hammer.
- Make sure that the concrete into which you are installing the friction anchor is dry and solid. The concrete should be poured solid from the footer and up to the top of the block--the footer should have an anchor that ties the filled block cell to the footer, but that is for another article. Place the anchors four feet apart. Drill a 1/2-inch hole into the concrete with a hammer drill and bit. Be careful not to break the concrete with the hammer drill. Blow out any remaining concrete dust before you place the anchor. If you are using epoxy--although not necessary--apply it to the hole first. Insert the anchor bolt and then install the sill. The bolt will tighten in the hole as you torque the nut tighter.
- A J bolt anchor bolt should be fastened around a piece of rebar that has an inverted j on its end. Insert the rebar into the block cell, pour the cell close to the top of the rebar, hook the J bolt anchor bolt to the end, and continue to fill the cell around the J bolt. Some builders pack old concrete sacks into the lower block cells and fill only the top cell, leaving the J bolt with little structural support. You should fill the cells completely solid, from the footer to the top of the block. Make sure that the J bolt is plumb and straight in the concrete before it dries.
previous post
next post