Transform a sandy no-go zone into a maintenance-free outdoor living space using manufactured boards.
When the owners of this beachside home extended up and back, they needed to cut into the sloping block, resulting in a change of level between the house and backyard.
A timber retaining wall was installed, but a solution needed to be found for the 1500mm wide strip of rubble that remained between the back of the house and the retaining wall.
The owners decided to cover the gap by building a timber deck matching the floor level of the home, extending from the back of the house to the retaining wall.
A low 15.6 x 1.5m deck was designed to be built DIY using H3 treated pine for the ledgers and joists, and H4 treated pine for the in-ground stump posts.
Choosing the type of decking to lay was an important decision. The deck had to be tough enough to withstand year-round exposure to the elements and the rigours of three young children playing on it, while being low maintenance.
The deck plan
The treated pine framing was clad with Ekodeck, an engineered composite decking material from Ekologix (ekologix.com.au).
Ekodeck boards come in 5.4m lengths, which worked well with the almost 16m long deck area.
Composite boards are extremely durable and easy-care, requiring neither oiling nor painting.
Made of natural fibres, including bamboo with reclaimed timber and recycled plastic, this product range is available in four colours with boards either 137mm or 88mm wide.
When planning a deck, ensure the timber sizes, spans and spacings meet Australian standards and check with council whether approvals are needed.
If using manufactured boards like Ekodeck, carefully read the manufacturer’s installation guide before commencing any work.
A 6mm gap is needed between Ekodeck boards. Cut 20 spacers from 70 x 35mm scrap timber with a circular saw. Use 4mm spacers for the butt-joined ends. To prevent the boards from mushrooming, countersink all pilot holes.
In warm climates, predrill holes slightly larger than the screw diameter, minimising joist penetration.
This will allow for any increased movement caused by expansion and contraction.
TIP Nailing is not recommended for composite boards.
Use a water level to transfer the house floor level to the ends of the wall at the back of the house and to the retaining wall. Measure down 23mm from these level marks, allowing for the thickness of the decking boards, to establish the ledger heights and set taut stringlines in position.
Prop the retaining wall ledgers in position to the set stringline and drill 4.5mm diameter pilot holes at 450mm centres. Use a 5mm hex drive bit to secure the ledgers to the wall using galvanised bugle screws. TIP Use a cordless impact driver or electric drill for maximum torque.
To prevent the retaining wall from carrying the deck’s weight, support the ledger on treated pine stumps. Cut a housing for the ledger in the top of each stump, then dig 300mm diameter holes 450mm deep. Secure the stumps to the ledger using bugle screws, then concrete them in position.
Drill 25mm recesses 20mm deep, then 12mm diameter holes through the ledger at 450mm centres. Prop the house-side ledger in position and drill holes in the wall with a 12mm masonry bit, securing with Dynabolts.
TIP Cut the house ledger to fit neatly around the downpipes.
Cut the joists to fit, then secure a joist hanger bracket on each end with clouts. Prop the first joist in position and use a builder’s square to set it square, then secure using galvanised clouts, flush with the ledger top.
TIP Spray the joist hanger brackets with a rust-guard paint.
Secure a trimmer between two joists, supporting a shorter joist to accommodate each downpipe. When the decking is being laid, use an offcut of stormwater pipe to mark the cutout on the board nearest the wall. Use a jigsaw to cut out the shape, keeping a gap of 6mm around the pipe.
Measure and mark the 450mm joist spacing on both ledgers. Working with a helper on the opposite side of the framework, square up each joist, then secure the hanger brackets to the ledgers using galvanised clouts.
TIP Cut 405mm wide timber spacers to speed up the process.
Set a stringline 287mm from the house wall to avoid the downpipes, then lay a row of boards against it
and drill countersunk clearance holes, securing with screws. Position the next row of boards, using a spacer
at every second joist to ensure the required 6mm gap is consistent.
Cut and secure timber blocking to each joist under the butt joints of the boards to stop the joists from splitting. Stagger the joints by changing the length of the starting board in each row from a full-length 5400mm board to an 1800mm board, then a 3600mm board followed by another full board.
Secure the remaining boards with pairs of screws at each joist, using a 4mm thick spacer to maintain the required gap at each butt joint. Use a stringline to check the alignment of the boards after every three rows are laid, scribing the last row of boards to fit the available gap.