Building a One-Level Deck

Get the most out of summer by building a deck for relaxing, entertaining, and enjoying time with friends and family. Follow this comprehensive guide to constructing a 12' x 12' deck in a single weekend. The structure needs to be secured to the foundation and made of treated wood, but the decking can be made of treated wood, composite wood, or cedar.

Difficulty level : 
Duration : 
1 week

Safety Considerations for Pressure-Treated Wood

When sanding, sawing, or working with treated wood, you need to wear long sleeves, gloves, a dust mask, and eye protection to protect against splinters, skin contact, and sawdust inhalation.

Treated wood should not be burned, its wood chips should not be used as mulch, animal bedding, or animal litter, and its sawdust or other remnants should not be disposed of in compost.

Building Code Standards: Deck Railings

The construction of buildings and structures, including decks, must follow the National Building Code of Canada guidelines. However, the standards may vary based on the local building requirements of different municipalities and provinces.

For deck railings, the minimum required height is dependent on the height of the deck as measured from the deck surface to the ground.

  • A deck surface with a height below 24" may have an optional or decorative railing.
  • A deck surface with a height between 24" to 5' 10" must have a railing of at least 36".
  • A deck surface with a height over 5'10" must have a railing of at least 42".

Important: The distance between balusters and between the bottom rail and the decking must be no more than 4". Stairway treads must also be no less than 9¼" deep and risers no higher than 8".

Before you start: Always refer to your local building codes to identify which codes apply to your building project.

Lay Out and Mark the Location of the Deck

  • 1.1

    Use strings and stakes to outline the deck's layout, running the string around the entire deck perimeter. 

  • 1.2Ensure the corner is square using the 3-4-5 rule: a measurement of 3' on one side and 4' on the perpendicular (adjacent) side should equal a 5' diagonal and a perfect square.
  • 1.3Remove grass, cover the area with a geotextile sheet, and cover the sheet with gravel up to 2" thick.
  • 1.4Consult your plan and mark the foundation pillar locations.
Calculator - Soil

Use Concrete Pillars to Build the Deck Foundation

In this project, you will be using a foundation of concrete pillars without footings, which is suitable for most types of decks. View the project for installing a deck foundation.
  • 2.1Dig holes to a depth of 54" with a diameter of approximately 10".
  • 2.2Place a form tube at the centre of each hole, ensuring the tubes are equal height to avoid the need for later adjustments.
  • 2.3Backfill around the tubes and pour concrete into each one.
  • 2.4Place a steel rod into every tube for reinforcement and to reduce structural damage from frost heaving.
  • 2.5Place the post saddle rods into each pillar's centre as well.

Install the Ledger Board Against the Foundation

Remove the clapboard siding on your home's concrete foundation 1' above the location where the ledger board will be installed. For a larger deck, double the ledger board size. Install flashing tape as well.
  • 3.1Consult your plan and mark the ledger board location.
  • 3.2Level the board against the wall of the house and at the correct height.
  • 3.3Drill holes in the ledger board and the house using concrete drill bits.
  • 3.4Use masonry anchoring screws to secure the board to the wall.
  • 3.5Caulk along the top of the ledger board and prevent water infiltration by installing galvanized steel deck flashing.

Install the Deck's Support Beams and Posts

  • 4.1Install the 4" X 4" posts into the saddles of the foundation posts, ensuring that they are square.
  • 4.2Mark the beam height on the 4" X 4" posts using chalk line and cut the posts.
  • 4.3Fasten two 2" × 10" boards together to build the support beams.
  • 4.4Use post saddles to install the beams on top of the 4" x 4" posts.
  • 4.5To mark the beams to the correct length, set a joist against the house and square it on the beams.
  • 4.6Cut the beams to length and apply a silicone seal along the top.

Install the Rim and Intermediate Joists

  • 5.1Secure the rim joists (end joists) to the ledger board using joist hangers, resting the other end of the joists atop the beam.
  • 5.2Mark the intermediate joist locations on the ledger board and beams at 16" centre-to-centre.
  • 5.3Use joist hangers to secure the intermediate joists to the beams and the ledger board.
  • 5.4Mark the joint lengths using chalk line and cut.
  • 5.5Install rim joists at both intermediate joist extremities.

Install the Decking Boards

If you are installing decking boards, they need to be laid perpendicular to the joists. Wood boards are installed using nails, while other flooring types may call for different installation methods and materials. Additionally, if installing fascia, ensure that the boards overhang the rim joists by about 1¼".
  • 6.1Start the installation off square by using chalk line to mark the first board's location.
  • 6.2Outer boards need to be installed to the joists with screws. To prevent splitting, pre-drill and screw the first outer board. Self-piercing screws work as well.
  • 6.3Nail in the rest of the boards and cover the entire deck surface during installation.
  • 6.4For dry wood, use a spacer nail between each board. For green wood, install the boards together tightly as they will contract when dry.
  • 6.5Frequently check that the boards are still square and adjust if necessary.
  • 6.6Nail any curved boards in the side to straighten them.
  • 6.7Adjust your spacing as you go so that you cover the entire deck surface without needing to cut the last segment next to the wall.
  • 6.8Cut the ends of overhanging boards to fit.

Build the Deck Stair Stringers

  • 7.1Consider the width of your stairs and calculate one stringer per each 16" to 24" interval.
  • 7.2Take the deck height (A) and divide by 7. Round down your result to the nearest whole number for the number of steps you will need.
  • 7.3Divide deck height by stair number for the height of the stair riser (B). Multiply your desired stair tread (C), typically 11", by the number of steps for the total length of the stairs (D).
  • 7.4Take a 2" × 12" board and start with the top step by holding a square on the corner with the (B) and (C) measurements, drawing a right angle.
  • 7.5Reposition the square along the board to mark the rest of the steps.
  • 7.6Mark the bottom edge of the stringer (E).
  • 7.7Measure the step covering board thickness (usually 2½") and subtract the thickness from the bottom of the stringer, drawing a parallel line across the board.
  • 7.8Double-check your measurements and mark the sections to cut away with an "X."
  • 7.9Cut the stringer with a circular saw and use a jigsaw to finish the cuts.
  • 7.10Check that the stringer fits by placing it against the rim joist.
  • 7.11Use your finished stringer as a template for cutting the others.
  • 7.12Install a 2" x 4" (F) under the rim joist to provide a nailing base for the stairs. Make sure that it overhangs the stringer by at least 4" for stability.
  • 7.13Use corner plates between the top of the stringers and the 2" x 4" for alignment and installation.
  • 7.14Ensure that the base of the stringers is lying flat on the ground.

Measure, Cut, and Install the Stairs

  • 8.1Cut the risers to the riser measurement (B) and screw them in first.
  • 8.2Add an additional 1" to the stair tread measurement (C) so that the steps cover the riser.
  • 8.3Determine how many boards you need to cover the steps. Adjust width as necessary.
  • 8.4Cut the boards to a width that exceeds the risers by an extra 2" on either side.
  • 8.5Lay the boards across the stairs and screw them into the stringers.

Install the Deck Guardrail

Installing 4" x 4" posts directly into the structure of the deck before the decking is laid offers increased stability. Alternatively, you can bolt the bases of the posts to the rim joists. The final option is attaching the railing to the deck directly with brackets and supports.
  • 9.1Cut the 4" × 4" posts to the guardrail height and mark the location of the posts around the deck perimeter.
  • 9.2Make sure you leave a 2" space between the exterior cladding and the brackets.
  • 9.3Mark the post locations on the first and last step as well, leaving a space of less than 4" between the first step and the post.
  • 9.4Screw in the post brackets, ensuring that they are square, and install them to the floor.
  • 9.5Mark the locations of the handrail (top rail) and the bottom rail.
  • 9.6Take the measurements between every post and cut the deck rails.
  • 9.7Place a rail against the stair posts to mark the cutting angles at each end. Use a mitre saw to cut the ends and check the fit. Do the same for the second rail.
  • 9.8Check that the railing brackets are square and screw them into the posts. Install the railing.
  • 9.9Make a mark every 4" along the rails for the balusters’ installation.
  • 9.10Pre-drill the balusters and then screw them to the top rail. Make a mark every 4" along the rails for the balusters’ installation.
  • 9.11Level the balusters, then pre-drill each one and screw to the lower rail.
  • 9.12Finish the posts with post caps.
Install railing

Install a Lattice Under-Skirting Around the Base

  • 10.1Build a 2" x 4" board frame under the bottom of the deck where you can install the lattice.
  • 10.2Build a frame for the lattice by measuring and cutting grooved rails at a 45° angle.
  • 10.3Cut the lattice to fit the frame. Insert it into the grooves and secure it with deck screws.
  • 10.4Install the lattice frame to the board frame under the deck.
Install lattice

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