How to Build a Low-Level Cedar Deck

Building a low-level patio deck is a quick and easy way to add a beautiful cedar outdoor living space to your garden. It is ideal when the height of the interior of the floor is close to the surface of the garden.

Being low to the ground, a platform deck does not require railings or stairs. It has an open airy feeling that makes it an ideal place for relaxing or entertaining.


Mark the area for your deck with stakes and string. To check the accuracy of the right angles create a right-angled triangle with sides 6 feet by 8 feet by 10 feet (or proportionate measurements). Using string, run two lines from a proposed 90-degree corner. Measure and mark points 6 feet from the corner in one direction and 8 feet in the other. A line connecting these two points and completing the triangle should be 10 feet in length. If it isn't, adjust the perimeter lines to square the corner. Once the perimeter is staked out, it is time to place the footings.

Footings and Posts

Next run string lines for each row of footings your deck requires. Measure along these string lines and drop a plumb bob to pinpoint all footing locations. Mark each by sticking a spike into the ground. For the foundation, dig holes for post footings 300mm square and 600mm deep. Pour 100mm of loose gravel in the bottom of each footing hole to provide drainage under concrete footings. Pour concrete footings and cast metal post anchors into the top to secure the posts. Mark posts to indicate tops of beams. On sloping terrain cut the posts to the length required to make the deck level.

Installing Beams

A deck beam is attached to the posts, and helps support the weight of the joists and decking. On a low level deck the joists butt into the beam rather than run across the top. Build each beam from a pair of pressure treated 50 x 150mm stress graded timbers held together with 4.0 x 60mm deck screws spaced every 450mm. Attach beams to posts with 5.0 x 150mm Rugged Structural Screws. Cut all post tops flush with tops of beams.

Hanging Joists

Joists provide support for the decking boards and should be spaced at either 400mm or 600mm on-centre depending on the thickness of the decking used. Measure along the beam and mark where each joist will be attached. Draw the outlines across the top of the beams. Attach joist hangers to the beams positioning each hanger so that one of the flanges is against the joist outline. Nail flange to framing member with joist nails. Cut a piece of scrap joist to use as spacer. Hold the spacer inside each joist hanger then close the hanger around the spacer then nail the remaining side flange to the beam with joist nails. Cut the joists to length and seal cut ends with a preservative. Position all the joists and run a string line across the tops. The joists should touch the line evenly. Attach the joist hangers to 50 x 150mm joists with joist nails. Attach 50 x 150mm rim joist to post using 7.0 x 100mm Rugged Structural Screw. Reinforce inside corners of rim joists with angle brackets attached with joist nails.

Laying Decking

Position deck boards so that ends overhang rim joists and space boards about 3mm apart to provide drainage. Attach decking by driving a pair of 60mm or 80mm (depending on the thickness of decking used) deck screws into each joist. Once the decking is down, snap a chalk line to mark straight cut-off lines flush with the outside edges of the rim joist, following these as you trim the boards together. When installing deck boards, it's important to avoid finishing with a partial board at the edge of the deck. To prevent this from happening, you can vary the spacing slightly between the last 12 or so boards on the deck. Begin measuring the distance to be covered when about 2 metres of "un-decked" width remains. By slightly adjusting the size of the space between boards, you should be able to finish with a full-width board.

Finishing a New Deck

Finish a new deck with Seasonite New Wood Treatment. An immediate application of Seasonite will seal out excess moisture and protect wood against fading keeping it looking new longer and providing mildew resistance. Seasonite penetrates into the wood and regulates the release of moisture, unlike some new treatments that just sit on the surface and are easily scuffed off. Apply one liberal coat of Seasonite to all wood surfaces using a brush, roller or garden spray. Work Seasonite into cracks between boards and allow it to soak into the end grain. Allow to dry overnight. Once the timber is seasoned - in a year or so - treat with Textrol Clear Penetrating Finish.


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