Deck, pergola and patio certification

What are the other exempt rules?

Any single deck, patio, pergola, terrace or verandah may be up to 25 m². A combined limit covers them all as well. Where the lot is larger than 300 m², the total may reach 15% of the ground floor area of the house. Where the lot is 300 m² or smaller, the total is 25 m².

Height is capped at 3 m above ground, and enclosing walls at 1.4 m. It must be set back behind the building line on every road frontage. Keep it 900 mm or more from each boundary, or 5 m in most zones that are rural or large-lot residential. Any metal components need a low reflective, factory pre-coloured finish. Where the roof attaches to the fascia, it has to be built to an engineer's design. Rainwater from the roof must drain into your existing stormwater system without disturbing current drainage.

Balustrade requirements

Under the building code, any deck, stair or landing with a potential fall of 1 m or more needs a barrier (balustrade). Deck barriers need a minimum height of 1 m. On stairs the barrier can be 865 mm above the step edges, and the top of the handrail must also be 865 mm or more above them.

If the drop exceeds 4 m, which is common on sloping blocks and upper decks, the barrier must not be climbable. Horizontal parts between 150 mm and 760 mm above the floor must not act as a ladder. That rules out many horizontal slat designs. Tensioned wire barriers have their own rules, including wire tension limits and support rails no more than 900 mm apart.

Timber decks in bushfire areas

On bushfire prone land, an exempt deck or roofed structure closer than 5 m to a house has to use non-combustible materials. If approval is needed, a deck linked to a house in a bushfire area must be built to AS 3959 or the steel framing bushfire standard, with NSW bushfire planning rules on top.

Your Bushfire Attack Level (BAL) decides how strict the material rules are. The scale starts at BAL-LOW and ends at BAL-FZ (flame zone). Open decks need materials with better ignition resistance. Fast-track complying development is ruled out on sites rated BAL-FZ or BAL-40, so a deck there needs a development application. On bushfire prone land, any deck closer than 6 m to a building must also satisfy the NSW bushfire planning rules. Pick decking and frame materials after the BAL is known, not before.

Stairs from a deck to the yard

Stairs leading off a deck follow the stair rules in Part 11.2 of the National Construction Code (NCC) Housing Provisions. Every flight has between 2 and 18 risers. On an ordinary straight stair, each riser is 115 mm to 190 mm high and each going, the horizontal depth of the step, is 240 mm to 355 mm.

A slope check applies as well: two risers plus one going must add up to between 550 mm and 700 mm. For example, 180 mm risers with 260 mm goings give 620 mm, which sits inside the range.

Risers and goings have to stay constant through each flight. Neighbouring steps can differ by no more than 5 mm, and the biggest and smallest in a flight by no more than 10 mm. Where risers are open, no gap between treads may be big enough for a 125 mm ball to slip through. Fix the finished level at the bottom of the stair before the stringers are cut, so the last step is not taller than the others.

Slip resistance and landings outdoors

Stair treads need a slip-resistant surface, or a nosing strip, rated under AS 4586. The tread surface must reach P3 or R10 when dry and P4 or R11 when wet. Outdoor stairs get rained on, so plan around the wet rating.

Where a landing leads onto a flight going down, that slip-resistant surface has to extend at least 190 mm back from the edge. Ask the supplier of the decking boards or tiles for their test classification before you order.

Landings must be at least 750 mm long, with a fall no greater than 1:50. One is needed where a door opens onto a drop of more than 3 risers or 570 mm, and it must run across the full width of the doorway. Raised decks where the back door opens straight onto stairs are a common place this rule bites.

Privacy screens on and around a deck

A freestanding privacy screen can go up without approval when its height is 2.5 m or less, measured from the existing ground level, and its length is 5 m or less. Keep it 900 mm or more from each boundary, and do not fix it to a boundary fence or a retaining wall. The concession does not extend to foreshore land.

Those limits describe a screen that stands on the ground. For a screen built onto a raised deck, go through the full privacy screen provisions in the Codes SEPP (the state planning policy for exempt and complying work) before treating it as exempt.

Planning exemption does not switch off the building code. The screen must still be strong enough for its job and put up the way its manufacturer specifies.

Shade sails over decks and patios

Shade sails and similar fabric covers are assessed under a separate exempt category for shade structures, not under the deck and pergola rules. To be exempt, a shade structure tops out at 3 m, taken from the existing ground level, and it must stay behind the line of the house facing every street.

Each boundary needs a 900 mm gap, rising to 5 m in the R5 large-lot residential zone and in rural zones other than RU5 villages. The Codes SEPP also caps its area. The exemption is lost in a foreshore area, on State Heritage Register land and where an interim heritage order applies.

Posts, footings and fixings must be sound enough to carry the sail and be put up as the manufacturer specifies, as with any exempt work.

Heritage areas and protected land

In a heritage conservation area, including a draft one, an exempt deck, patio or pergola has to be located further back than the building line facing each road. That keeps new outdoor structures out of the streetscape.

The exempt rules generally do not reach land on the State Heritage Register or land protected by an interim heritage order. Wilderness areas and declared critical habitat are excluded too. On any of these, a deck or pergola needs approval, however small it is.