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How to build a wood patio deck

A wood patio deck extends the living space of the home to the outdoors, providing a homeowner with an attractive area to entertain, relax and enjoy outdoor living.

While the construction of a wood deck is relatively simple, the entire process of planning, permitting, framing and decking requires time and careful preparation. Here are some building basics.

Check the zoning requirements of your municipality. Most zoning ordinances require setbacks, or no-build zones, for all sides of a property. Setbacks limit the area in which a deck may be built. Also check the buiding permit submission requirements for decks to determine the drawings that must be submitted for a building permit.

Examine the entire area where the deck will be constructed. Where will the steps to the yard be located? How does groundwater drain across the area? Is there a view to a road or neighbouring property that is undesirable? Assessing the entire yard in relation to the planned deck is essential to make the deck work well with home and yard.

Plan the deck on paper. Begin with the overall dimensions and location of critical pieces, such as stairs and raised sections. Gradually add on more detail as the design takes shape, including direction and type of decking.

Plan the foundation. A deck is normally supported on 4x4 treated lumber posts, which are set on galvanised post anchors embedded in 8- to 10-inch diameter concrete footings. Check the frost depth for your area to determine the minimum foundation depth. Lay out a foundation plan that results in joists spanning no more than 10 feet.

Prepare the building code permit documents. These normally consist of a foundation and framing plan, foundation detail, and step and railing dimensional information. A zoning permit may also be required. For this permit, show the deck dimensions on a property survey to demonstrate compliance with setback requirements.

Begin construction by laying out the foundation locations on the ground. Use a system of strings and batter boards to construct a rectangular grid. Check for squareness often, and measure along the grid lines as well as diagonally to ensure that the deck is not skewed.

Attach the ledger board to the foundation wall of the home using lag bolts. A ledger board is often used in deck construction as a framing attachment adjacent to the house. Set the location of ledger board carefully, making sure that the thickness of the deck and desired slope has been taken into account.

Grade the area beneath the deck, establishing a smooth surface that drains away from the house. Install black plastic sheeting over the ground, and weight it down with gravel or a regular spacing of stones, being careful not to obstruct water flow under the deck.

Use a post hole digger or auger to dig the footings to the proper depth below the frost line. Pour the footings with concrete mix, and set the galvanised post anchors into the top of the footing before it sets up. Ensure the anchor is in line with other footing anchors, and plumb (vertical).

Set the 4x4 treated posts into the post anchors, leaving them long for final cutting later. Bolt a 2x8 joist to the outside of the 4x4 posts, creating the rectangular box (band joists) that will form the outside dimensions of the deck. Install joist hangars at 16-inch intervals within the rectangle. Measure frequently to make sure that all joists are square to the outside perimeter.

Lay the joists into the joist hangars and nail with galvanised nails to securely attach. Install 2x8 blocking at the midpoint of all the joists. The blocking helps the entire structure to function as a unit. Secure the stair stringers to the side of the frame with a 2x2 ledger or toenail attachment.

Install the railing verticals before beginning decking. Depending on the style of railing, these verticals may lag bolt to the outside or inside of the band joist. Lag the verticals securely in place at the required intervals, checking for plumbness.

Install the decking perpendicular to the joists. Use a nail or other spacing device to allow approximately 1/8-inch separation between decking boards to allow for expansion.

Use a line level and shims to adjust the decking elevation to ensure drainage across the face of the deck (in the direction of the decking). A slope of 1/8-inch per foot is sufficient.

Allow the decking to overhang the framing during installation. Strike a pencil line across the decking edge later to cleanly trim the edge with a circular saw.

Install the trim boards around the edge of the deck for a finished appearance. The trim may need to be installed in two pieces, with the upper piece trimmed out, to cover the depth of the joist.

Deck the stair treads and runners, allowing a 1-inch nosing on the steps. Install the railing balusters and verticals around the perimeter, sand all rough edges, and check for raised screws or nail heads.

Apply stain or clear finish to the decking and railing for a finished appearance.


Check zoning setback requirements first. Look at the use of the entire yard when planning the deck. Choose the decking material early. Its thickness affects the framing.


Call for the required building code inspections (normally footings and framing). Check the posts for plumbness. Check the level and slope frequently. Call for a utility markout before digging for deck footings.

Things Needed

  • Post hole diggers
  • Concrete mix
  • Post anchors
  • Joist hangars
  • 4x4 treated posts
  • 2x8 treated joists
  • Galvanised nails
  • Hammer
  • Square
  • Measuring tape
  • String level
  • Bubble level