How to Build a Ledger to a Concrete Block

Ledgers often hold beams, called joists, that support a structure's subfloor.

Ledgers transfer the load from joists or beams to a masonry surface, such as a concrete block wall. The essential component of a ledger connection is anchorage. Concrete anchors are the most common method of anchoring a ledger to a concrete wall. Builders frequently use anchors called "expansion anchors" or "wedge anchors" for ledger installation. The wedge anchor looks like a headless bolt with a wedge-shaped butt. The anchor's butt is hollow and, when the builder pounds the butt into a predrilled hole, it expands and grips the side of the masonry surface. With wedge anchors installed, builders simply place a ledger board over the anchors and fasten the board with washers and nuts.

Things You'll Need

• Ledger board
• Pencil
• Combination hammer drill
• Wood drill bit
• Level
• Masonry drill bit
• Electrical tape
• Expansion anchors
• Anchor nuts and washers
• Hammer
• Adjustable wrench
• Assistant

Instructions

1. Lay the ledger board on a flat surface. Use a pencil to mark the location of each anchor bolt. Although specifications vary according to building plans and local codes, place two bolt marks at each end of the board and "stagger," or alternate, the position of bolts approximately every 16 inches between the ends. Attach a wood bit to a combination hammer drill. Bore a hole through each anchor bolt mark.

2. Hold the ledger against the wall in the desired position; have a partner help you if the ledger is too heavy or long to manipulate on your own. Place a level on top of the ledger and adjust the ledger to a level position. Push the pencil through each bolt hole to create a mark for each hole on the wall. Remove the ledger from the wall's surface. Attach a masonry drill bit to the drill.

3. Flip the drill's function switch from the drilling position to the hammering position. Affix a piece of tape around the shank of the masonry drill bit at a position that corresponds to the proper depth of the anchor bolt hole. The hole depth equals the length of the bolt minus the amount that the bolt must protrude from the wall. The bolt must protrude far enough from the wall to pass through the ledger board and accept both a washer and nut.

4. Drill into each hole mark on the wall until the electrical tape meets the wall's surface. Blow air into each hole to release concrete dust. Place a washer on each bolt. Thread a nut onto each bolt. Position the ledger over the bolt holes and have your assistant hold the ledger in place. Place a bolt into a predrilled bolt hole and pound the bolt until its wedge expands and grips the sides of the hole. Pound a bolt into each hole.

5. Attach an adjustable wrench to one of the bolt's nuts. Twist the wrench to tighten the nut and washer against the ledger's surface. Use the wrench to fully tighten each nut against the ledger and secure the ledger flush against the wall.

Tips & Warnings

• If you do not attach washers and nuts before pounding expansion anchors, you will deform the threads and prevent subsequent attachment.

References

• Professional Deck Builder Online; Ledgers on Challenging Walls; Andy Engel
• National Concrete Masonry Association; Floor and Roof Connections to Concrete Masonry Walls; 2001