Brett Field
Picture frame decking is a deck with a border of boards running around its edge. The main boards stop against the border, so the edge shows one long board instead of a row of cut ends. Ekodeck says picture framing gives its composite decks a clean finish and strongly recommends it.
Below is what it looks like, why people choose it, the extra framing it needs, how timber and composite differ at the corners, what it does to the price, and what to watch on the Gold Coast. The details come from the board makers' install guides and the timber industry's deck guides, checked on 27 October 2026.
What does a picture frame deck look like?
The main boards, called the infill, run one way across the deck. Border boards run around the outside edge. Where two border boards meet at a corner, they are usually cut at 45 degrees and joined in a mitre, the same way a picture frame is.
Trex's Australian guide lists a few ways to change the look:
- a border in a contrasting colour, or the same colour as the infill
- two border boards side by side, for a wider frame
- extra borders through the middle that split the deck into sections
- infill boards laid on an angle inside the frame
- fascia in the border colour, so the frame seems to wrap down the side of the deck
Ekodeck also offers a herringbone corner instead of a mitre, which it says handles expansion and contraction better.
Why do people picture frame a deck?
Mostly for a finished edge. Without a border, every infill board ends at the edge of the deck, so you see a line of cut ends. TimberTech calls the framed version "a clean finished look".
There are practical reasons too:
- Fewer butt joins. When boards are too short to cross a deck, they are joined end to end. Trex says borders through the middle of a deck can remove the need for these joins. Ekodeck advises against butt joins in its boards on any size of deck, and suggests a breaker board (a cross board through the middle) on decks longer than 5.4 m.
- Less debris at the edge. Trex says a border that overhangs the fascia helps keep leaves and dirt out of the gap between the fascia and the joists.
- Pool and stair edges. A border gives a straight, finished line where a deck meets a pool or the top of the stairs. Trex suggests matching the border to the stair risers and the infill to the treads.
What extra framing does a picture frame deck need?
More joists or blocking under the border. Trex's Australian guide calls the blocking "the most important step" and the main difference from a standard deck. Here is what four makers ask for.
| Guide | What goes under the border |
|---|---|
| Trex Australia (2024) | Two extra joists on each side where the border runs the same way as the joists: one under the border's inner edge, one under the infill ends. None needed at the outside rim joist. |
| TimberTech (US) | Every infill board end fully supported. Extra blocking or joists no more than 406 mm (16 inches) apart, or 305 mm for a firmer feel, plus blocking at each mitred corner. |
| Ekodeck (V10.25, 2025) | Noggins between the joists under the border, shown in its picture frame drawings. |
| ModWood (2021) | A double joist, or a block fixed to the joist, wherever board ends meet, because screws must stay back from the ends. |
A border board that runs the same way as the joists has nothing to sit on unless extra framing goes in under it. The infill boards that stop against it need something to fix to as well. TimberTech says all the extra framing must sit level with the tops of the joists and be screwed, not nailed. Trex says you will need four or more extra joists, plus hangers, fasteners and flashing tape.
Timber Queensland recommends joists 45 to 50 mm wide, because they split less and give better fixing at board joins and ends. Our guide to deck joist spacing covers the spacing under the infill.
What gap goes at a mitre joint?
Composite makers set a small gap, which depends on the temperature on the day.
- Trex: its picture framing guide and 2024 install guide ask for 1/8 inch (about 3 mm) at a mitre above 4.5°C, and 3/16 inch (about 5 mm) below that. The same gap goes between the infill ends and the border.
- Ekodeck: a mitre gap 2 mm smaller than its normal end gap, "to reduce the likelihood of gaps opening".
The timber guides do not cover mitres. For butt joins, Timber Queensland and WoodSolutions say to fit the board ends tight, with a slight back-cut so the top edges close up. The full side and end gaps for each board type are in our guide to decking board spacing.
Timber or composite: which suits a picture frame better?
Both work, but they move in different ways, and that shows at the corners.
| Timber | Composite | |
|---|---|---|
| How it moves | Across its width, as it takes up and loses moisture | Along its length, with heat |
| Fixing at board ends | At least 12 mm from the end, holes pre-drilled (WoodSolutions) | Screws kept back from the end, so a double joist or block goes under it (ModWood) |
| Cut ends | Seal every cut end (WoodSolutions) | Seal cut ends near pools and spas (Ekodeck) |
| Long decks | Staggered butt joins (Timber Queensland) | Breaker boards (Ekodeck) |
The US trade magazine Journal of Light Construction explains what happens at a timber mitre. A dry board that swells opens the long point of the joint, and a wet board that dries opens the short end. Its advice is to pick boards of similar grain, colour and moisture. WoodSolutions says to put a protective finish on every face of timber decking, including freshly cut ends, and lists unsealed cut joints as a common deck problem.
Composite borders are part of each maker's system. Trex says to use square-edge boards for the border, because its grooved boards are made for hidden clips. People on Bunnings Workshop ask how to clip down Ekodeck picture frame boards. For its 3 mm clip system, Ekodeck's manual answers that one: C-clips or modified standard clips every 450 mm.
Does picture frame decking cost more?
Yes, but none of the cost guides we checked puts a figure on it, so we will not guess one. The extra cost comes from three places in Trex's guide:
- Framing: four or more extra joists, plus hangers, fasteners and flashing tape.
- Boards: border boards hang a little past the frame, so they must be slightly longer than the deck.
- Time: Trex says a border takes "extra construction steps and materials, and additional design and layout work". Every corner is a mitre cut.
For what a whole deck costs per m2, see our deck cost guide for the Gold Coast.
What should you know about picture frame decks on the Gold Coast?
Heat. At the Gold Coast Seaway weather station, the average daily top is above 25°C every month from October to April, and 28.9°C in January. ModWood says to fix its boards when it is under 25°C and they are out of full sun, because a board in the sun runs 20 to 25°C hotter than the air. Mitre gaps are set by the temperature on the day, so cut and fix composite borders in the cool of the morning.
Salt air and pools. ModWood says only stainless steel clips, or two named KlevaKlip models, can be used around pools and within 1 km of salt water. Ekodeck says board ends near a pool or spa must be sealed with a clear, solvent-based paving or concrete sealer, and it recommends 316 stainless steel screws into timber joists. Our decking timber guide covers fixings near the beach.
Termites and framing. The extra joists and noggins are deck framing, so the same rules apply. Timber Queensland says treated pine framing more than 150 mm above the ground must be H3, and framing on the ground H5. WoodSolutions says pine treated only to H2 is not suitable for decks.
Air flow. A border with a fascia can close in the deck's edge. ModWood says not to seal off the deck ends, and WoodSolutions says a low deck's perimeter should be kept open for air.
We build timber and composite decks across the Gold Coast, including pool decks and deck stairs, with or without a border. You get a timeline with the proposal, before any work starts. See our deck building page for what we build.
Where do these figures come from?
Checked on 27 October 2026: Trex Australia's picture framing guide (November 2024) and the Trex 2024 Decking Installation Guide; TimberTech's picture frame guide (US, undated); the Ekodeck Designer Series product manual (V10.25, October 2025); ModWood's decking fixing instructions (2021); Timber Queensland Technical Data Sheet 4, Residential Timber Decks (revised March 2014); WoodSolutions Technical Design Guide 21, Domestic Timber Deck Design (revised October 2020); Journal of Light Construction, "Movement in Mitered Corners" (March 2010); and Bureau of Meteorology climate statistics for Gold Coast Seaway (prepared 22 October 2026). The metric conversions are ours. We will check the figures again every three months.
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