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Home / Composite decking / Accessories / Fixing system
Fixing: the hidden clip, the screw, the anchor
No screw goes through the face of a Tarimatec board. Each board is held by a stainless clip that also sets the gap to its neighbour, so the finished surface is unbroken and the expansion gap is right by construction rather than by eye.
The fixing set
Dimensions and grades are from the 2025 Tarifa and the Manual Tecnico 2023. The clip is available in two stainless grades; which one you specify depends on how much salt the deck will see.
Hidden clip H, AISI 304L
The standard fixing clip: stainless steel, 40 x 45 mm, one per board per joist crossing. It locks the board down and holds the gap open for drainage and thermal movement.
- Stainless AISI 304L, 40 x 45 mm
- 25 clips per m2 of deck
- No visible fixings on the walking surface
Hidden clip H, AISI 316L
The marine-grade option. Specify 316L for saline environments: coastal decks, salt-water pools, and rooftops where de-icing salt is used. Supported by the manufacturer's salt-environment certificate.
- Stainless AISI 316L, same geometry
- Specified on request, quoted per project
- Recommended wherever chloride exposure is expected
Start clips, screws and anchors
The perimeter runs are held by start clips; the clips themselves are screwed to the aluminium joist; the joist is anchored to the structure.
- Start clip, AISI 304L, 32 x 29 x 10 mm
- Screw DIN 7504P, stainless A2, 4.2 x 25 mm
- Anchors: minimum 6 mm section, 35 mm penetration
One clip, two boards, one gap
Quantity rules
- 25 clips per m2 of deck: about 22 fixing clips plus 3 start clips (Tarifa 2025).
- 25 screws per m2, DIN 7504P stainless 4.2 x 25 mm.
- One clip at every crossing of board and joist; joists at 350 mm centres maximum.
- Approx. 3.5 linear metres of aluminium joist per m2.
- Approx. 2.6 boards per m2 at 2,500 mm lengths, before cutting waste.
- These are suggested quantities for regular rectangular layouts. Curves, steps, hatches and diagonals need more.
Both the hollow and solid profiles use the same clip and the same screw, so a mixed-profile deck needs one fixing schedule, not two.
304L or 316L?
| Situation | Specify | Why |
|---|---|---|
| Inland residential terrace or garden deck | AISI 304L | Standard grade; the clip is not exposed to chloride |
| Freshwater or chlorinated pool surround | AISI 304L | Standard grade, with the usual rinse-down care routine |
| Coastal deck, salt-water pool, marina | AISI 316L | Molybdenum content resists chloride pitting |
| Rooftop or entrance deck treated with de-icing salt | AISI 316L | Winter salting is a chloride exposure like any other |
| Hospitality or commercial deck with a long service life | AISI 316L | Small cost line, removes a long-term maintenance risk |
Grade upgrades are a per-project line on the quote, not a separate order. Ask for the salt-environment certificate with your technical pack.