How to Build an On-Grade Deck

Choosing to build an on-grade deck instead of an elevated deck eliminates many of the conundrums commonly associated with deck building. Because an on-grade deck is only one step high, it does not require steps or railings. While deck building is a challenging task for most home owners, an on-grade deck can be accomplished more quickly--and for less cost-- than a comparable elevated deck.

Things You'll Need

• 2-inch x 10-inch pressure treated lumber
• Pressure treated or composite decking boards
• Decking screws
• 1/2-inch by 8-inch lag screws
• 1/2-inch washers
• Shovel
• Screed
• Tamper
• Post hole digger
• Tubular fiberboard
• Concrete mix
• Trowel
• Self-adhesive waterproof membrane
• Nails

Instructions

1. Remove the siding from your house up to 1 foot above where the top of your deck will sit. Cover the area with self adhesive waterproof membrane.

2. Nail the ledger board (a section of 2-inch by 10-inch pressure-treated board that runs the length of the deck) to the wall in the desired location; if there will be a step down to the deck's surface, it must be 4 to 7 1/2 inches below the door sill. Drill pilot holes through the ledger board in a zig-zag pattern. Place a washer on each lag screw and insert it through the ledger board and into the foundation of the house.

3. Cut another length of the waterproof membrane. Fold it lengthwise; one part of the folded membrane will cover the thickness of the ledger board. Attach the membrane to the wall and over the top of the ledger board. Drive roofing nails through the membrane and into the top of the ledger board at 8-inch intervals.

4. Attach joist hangers to each end of the ledger board with joist hanger nails. Mark lines for the rim joists (the doubled 2-inch by 10-inch boards that will form the sides of the deck) and dig pier holes at 8-foot intervals. The holes should extend below the frost line, which can be 4 to 6 feet deep. Use a level to determine the height of each pier so that the finished deck will be level. Continue this process across the front of the deck.

5. Create concrete piers using tubular fiberboard. Pour the concrete through the fiberboard, and level each one with a trowel. Attach post brackets into the concrete while it is still wet, making sure to leave room for a double thickness of 2-inch by-10-inch lumber.

6. Allow the concrete to cure for 1 week.

7. Nail together a pair of 2-inch by 10-inch boards to form each of the rim joists. Attach the joists to the piers. Install joist hangers at 8-inch intervals along the ledger board and front rim joist, making sure that the tops of the interior joists will sit flush with the tops of the rim joists.

8. Install 2-inch by 10-inch trim boards to the faces of the rim joists with 8d (8-penny) nails. Measure, cut and lay the decking across the joists. Nail the decking boards to the joists with 8d nails. Sand and seal the ends of the decking boards.

References

• This Old House: How to Build a Simple Deck