Deck Building 5 - Drilling Holes for the Ledger

Margin of Error: 1/4”

Most Common Mistakes

  1. Using a badly bowed board.
  2. Not using rustproof lag screws or bolts.
  3. Not installing ledger at proper height or location.
  4. Not caulking bolt holes before installing ledger.
  5. Drilling holes where joists will be attached.

After you have decided on the placement of the ledger, in regard to both its height and its location on the wall, you are ready to install it.

Choose a good straight piece of ledger stock (usually the same size as the joists) and cut it to the proper length. Again, this is the total length of the deck less 3”. Now you can drill holes in the ledger for the lag screws or bolts that will hold the ledger to the house. These holes are drilled with a bit that is 1/8" larger than the actual screws so that you will have a little play for adjustments. Usually the holes are in pairs, one on top of the other, every 30”, or staggered singly every 15”. Be sure that all holes are drilled at least 1” more from the edge of the board for proper holding. You may want to check with the local code to see if there are any regulations concerning the location of these lag screws.

With the ledger resting on saw horses, begin at one end and mark the lag screw locations. Always drill a pair of holes 12” in from either end. Drill all needed holes.

You are now ready to temporarily attach the ledger to the wall, mark the corresponding holes on the siding, remove the ledger, and drill the holes in the siding. If there is a slight bow in the board, turn this toward the sky, since it is easier to push it down to get it straight.

Place the ledger’s top edge at the mark you have located on the wall that represents the top of the ledger and nail one end temporarily in place. Then place a 4’ - 8’ level on the board, get it exactly level, and temporarily nail in the other end. The ledger is now temporarily nailed in its proper place. Check once again to be sure it is exactly level before marking the holes. Then, with a felt-tipped pen or sharp pencil, mark the lag screw holes that were drilled in the ledger on the wail. Now remove the ledger.

You are now ready to drill the lag screw holes in the wall. Do not use the same size bit that you used on the ledger. Use a bit that is one size smaller than the shank of the lag screw. This will assure that the lag screw has a good bite into the wall. Drill all the holes, being sure to hold the drill straight so the lag screws will go in straight. Again be sure that you are drilling into solid wood, or use the blocking and bolt method described earlier.

After removing the ledger, as a precaution before you attach the ledger permanently to the wall, squirt some silicone caulk in the holes in the wail before screwing in the lag screws. This will help keep rainwater running down the wall from flowing into the structure through the lag screw holes.