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How to Build a One-Level Deck

Open the door to summer enjoyment with a deck in the backyard. Literally! This 12’ x 12’ deck is a single weekend job. The structure must be made of treated wood and secured to the foundation. The decking is up to you: treated wood, cedar, or composite material.

Pressure-Treated Wood: Safety Considerations

  • Wear gloves, long sleeves, eye protection and a dust mask when sawing, sanding or working with treated wood to protect against skin contact, sawdust inhalation, and splinters. It’s for your own safety!
  • Do not dispose of treated wood remnants or sawdust in compost heaps. Do not use treated-wood chips or mulch and do not use as animal bedding or litter.
  • Never burn treated wood.

Building Code Requirements

The National Building Code of Canada establishes guidelines for the construction of buildings and various structures, including decks. However, these standards can vary depending on the local building requirements in effect in a particular province or municipality. Deck materials should be chosen based on code requirements, available space, and personal preferences.

The minimum required height of the railing is based on the height of the deck, from the ground to the deck surface:

  • Deck height lower than 24": optional or decorative railing
  • Deck height from 24" to 5' 10": 36" railing
  • Deck height over 5'10": 42" railing
  • Note:
  • The maximum distance between balusters and between the decking and the bottom rail is 4".
  • For a stairway, treads should be no less than 9¼" deep and the risers no more than 8" high.
Patch of soil with strings and stakes marking a perimeter

Layout and Ground Preparation

  • 1.1 - Mark the layout using string and stakes when planning the construction of a deck.
  • 1.2 - Run the string around the entire perimeter.
  • 1.3 - Use the 3-4-5 rule to check that the layout is square: measure 3' on one side and 4' on the adjacent (perpendicular) side; the diagonal should measure 5'.
  • 1.4 - Remove the grass and cover with a geotextile sheet.
  • 1.5 - Cover the sheet with 1" to 2" of gravel.
  • 1.6 - Mark the location of the foundation pillars according to your plan.
Concrete tubes in the ground

Build a Foundation Using Concrete Pillars Without Footings

This project proposes a foundation using concrete pillars without footings, a type of foundation suitable for most decks. View the project: Four types of foundation for your deck.
  • 2.1 - Dig holes 54" beneath the surface of the soil and approximately 10" in diameter.
  • 2.2 - Insert a form tube in the centre of each hole.
  • 2.3 - Make sure the tubes are level and of equal height to minimize the need for subsequent adjustments.
  • 2.4 - Backfill around the tubes
  • 2.5 - Pour concrete into the tubes
  • 2.6 - Insert a steel rod into each tube to reinforce the pillar and reduce structural damage due to frost heave.
  • 2.7 - Insert the post saddle rods in the centre of each pillar.
Ledger board secured to a house

Install the Ledger Board on the House

The ledger board is installed directly against the concrete foundation of the house. Remove the clapboard siding 1' above the location for the ledger board and install flashing tape. Double the size of the ledger board for a large deck.
  • 3.1 - Mark the location of the ledger board according to your plan.
  • 3.2 - Level the ledger board at the correct height, on the wall of the house.
  • 3.3 - Use concrete drill bits to drill holes in the ledger board and wall of the house.
  • 3.4 - Secure the ledger board to the house with masonry anchoring screws.
  • 3.5 - Caulk the top of the ledger board and install galvanized steel deck flashing to prevent water infiltration.
Deck support beams

Install the Posts and Beams

  • 4.1 - Put the 4" X 4" posts in the foundation post saddles. Check that the posts are square.
  • 4.2 - Use a chalk line to mark the height of the beams on the 4" X 4" posts.
  • 4.3 - Cut the 4" X 4" posts.
  • 4.4 - Build the support beams by fastening two 2" × 10" boards together.
  • 4.5 - Attach the beams to the top of the 4" x 4" posts with post saddles.
  • 4.6 - Square a joist on the beams and mark the length of the beams.
  • 4.7 - Cut the beams to the correct length.
  • 4.8 - Place a silicone seal on the beams.
Joists secured to a deck ledger

Install the Rim Joists and Intermediate Joists

  • 5.1 - Use joist hangers to secure the rim (end) joists to the ledger board. Rest the opposite ends of the joists on the beam.
  • 5.2 - Mark the location of the intermediate joists at 16" centre to centre on all beams and the ledger board. Secure the intermediate joists to the ledger board and to the beams with joist hangers.
  • 5.3 - Use a chalk line to mark the length of the joists. Cut.
  • 5.4 - Install the rim joists at both extremities of the intermediate joists.
Planks of pressure treated wood on a deck

Install the Decking

Decking boards must be laid perpendicular to the joists. Wood boards are nailed in, while other types of floor may require different materials and installation methods.
If you are installing a fascia, the boards should overhang the rim joist by approximately 1¼".
  • 6.1 - Use a chalk line to mark the location of the first board in order to start off the installation square.
  • 6.2 - Outer boards must be screwed into the joists. Pre-drill and screw the first board to the joists to prevent splitting. You can also use self-piercing screws.
  • 6.3 - Nail in the boards to cover the entire surface of the deck. If the wood is dry, use a spacer nail between the boards during the installation process. If the wood is green, place the boards tightly together; the boards will contract as they dry.
  • 6.4 - Check regularly that the boards are square and adjust the spacing if necessary.
  • 6.5 - If a board is curved, nail it in the side to straighten.
  • 6.6 - Adjust the spaces to cover the entire surface without having to cut the last segment located next to the house.
  • 6.7 - Cut off the ends of overhanging boards.
Deck stairs with measures

Build Stringers for the Stairs

  • 7.1 - Calculate one stringer for every 16" to 24" interval. Measure the height of the deck (A) and divide by 7. Round up to the nearest whole number to get the number of steps.
  • 7.2 - Divide the height by the number of steps to get the height of the riser (B). Multiply the number of steps by the depth of the stair tread you want, usually 11" (C) to obtain the length of the stairs (D).
  • 7.3 - Start with the first step on top of the stringer. Hold a square on the corner of a 2" × 12" board with the (B) measurement and the (C) measurement. Draw a right angle.
  • 7.4 - Reposition the square and mark the cutting lines for the other steps.
  • 7.5 - Draw the bottom of the stringer.
  • 7.6 - Measure the thickness of the step covering, usually a 2½" board. Remove this measurement from the bottom of the stringer and draw a parallel line.
  • 7.7 - Check your measurements and put an “X” on the sections to cut.
  • 7.8 - Use a circular saw to cut the stringer and finish the cuts with a jigsaw.
  • 7.9 - Press the stringer against the rim joist to check that it fits.
  • 7.10 - Use this stringer as a template to mark and cut the others.
  • 7.11 - Install a piece of 2" × 4" under the rim joist at the location of the stairs (F). In order to ensure a solid nailing base, make sure that the pieces of 2" × 4" overhang each stringer by at least 4".
  • 7.12 - Align and install the top of the stringers the 2" × 4" with corner plates.
  • 7.13 - Lay the base of the stringers flat on the ground.
Deck stairs assembly

Assemble the Stairs

  • 8.1 - Measure the height of the riser (B), which should be the same as before.
  • 8.2 - Screw the risers in first.
  • 8.3 - Measure the depth of the step (C) in order to cover the riser with an additional 1".
  • 8.4 - Determine the number of boards to cover the steps and adjust the width of the board when necessary.
  • 8.5 - Cut the boards according to the width of the steps in such a way as to exceed the risers by 2" on each side. Lay all the boards on the stairs.
  • 8.6 - Screw the boards into the stringers.
Deck guardails with various measures

Install the Railing

For increased stability, 4" × 4" posts should be installed directly onto the deck structure before the decking is laid. Another option is to bolt the post bases to the rim joists. The last option is to attach the railing directly to the deck using supports and brackets.
  • 9.1 - Cut the 4" × 4" posts according to the height of the guardrail.
  • 9.2 - Mark the location of the 4" × 4" posts around the perimeter of the deck. Leave a 2" space between the brackets and the exterior cladding of the house.
  • 9.3 - Mark the location of the 4" × 4" posts on the first and last step of the stairs. Ensure that the space between the post and the first step is less than 4".
  • 9.4 - Screw in the brackets under the posts. Check that they are square and install to the floor.
  • 9.5 - Mark the location of the bottom rail and top rail (hand rail).
  • 9.6 - Measure the distance between posts and cut the rails for the deck.
  • 9.7 - Place a rail on the stair posts and mark the cutting angle at either end.
  • 9.8 - Make a mitre cut at each end and check. Repeat for the second rail.
  • 9.9 - Check that they are square and screw in the railing brackets to the 4" × 4" posts. Install the rails.
  • 9.10 - Make marks every 4" on the rails where the balusters will be installed.
  • 9.11 - Predrill then screw balusters to the top rail.
  • 9.12 - Level the balusters then predrill and screw them to the lower rail.
  • 9.13 - Set post caps on the posts.
Wooden lattice on the grass beside a deck

Install Lattice Under-Skirting Around the Deck

  • 10.1 - Build a frame with 2" × 4" boards around the bottom of the deck to nail in the lattice.
  • 10.2 - Measure and cut grooved rails at a 45° angle to build the frame that will support the lattice.
  • 10.3 - Cut the lattice to measure.
  • 10.4 - Insert the lattice into the groove and use deck screws to secure.
  • 10.5 - Attach the lattice frame to the base at the bottom of the deck.

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