How to Install Composite Decking Around an In-ground Pool: Our Complete Guide

A gorgeous pool deserves an equally impressive surrounding. Composite decking gives Kiwi homeowners a barefoot-friendly surface that shrugs off UV, chlorinated water and gritty togs, all while looking like freshly oiled timber. It is also low-maintenance and carries long warranties, so you spend more time swimming and less time sanding. Below is a start-to-finish walkthrough tailored to New Zealand conditions, codes and climate, packed with practical installation insights for poolside composite decking projects.

Quick Table of Contents

• Pre-build planning
  
• Preparing the sub-base
  
• Building a code-compliant frame
  
• Laying composite boards
  
• Trimming, fascia and pool-edge detail
  
• Safety checks before the first splash
  
• Cleaning and care
  
• Typical costs in Aotearoa
  
• Frequently asked questions
  
• Next steps
  

1. Pre-build Planning Your Deck

Check the rules first

• Deck height: A building consent is not required if nobody can fall more than 1.5 m from your finished deck surface, though a barrier is mandatory once the drop exceeds 1 m.
  
• Pool barrier: Clause F9 of the Building Code demands a continuous fence or pool wall at least 1.2 m high, with no gap larger than 100 mm.
  
• Slip rating: Choose boards with a certified P4 or higher anti-slip profile tested to AS 4586 for peace of mind on wet feet around your in-ground pool.
  

Pop into council with a site plan showing the swimming pool, deck outline and finished heights. Getting the thumbs-up early avoids painful halts once the joists are in.

Measure twice, sketch once

Grab a tape, and mark pool length, width and any bulges from steps or swim-outs. Add at least 900 mm of clear walking space all round so loungers, toys and adults can pass one another comfortably. A curved coping looks stunning against straight decking boards, yet it requires more trimming time, so budget accordingly and explore different design options first.

Select materials

• Framing: H3.2 treated pine or galvanised light-gauge steel bearers resist splash damage.
  
• Boards: Millboard, Trex, Futurewood and Ekodeck all offer UV-stabilised ranges in NZ. Many include hidden clip systems that keep screws away from tender toes and pool liners.
  
• Fixings: Stainless-steel screws or manufacturer-supplied concealed clips plus galvanised bolts for the ledger ensure proper installation.
  

2. Preparing the Sub-base 

A pool deck sees constant drenching, so drainage is vital.

1. Excavate any soft soil until you reach firm ground.
   
2. Lay geotextile to stop weeds, then spread 50 mm of GAP 20 compacted hard-fill.
   
3. Set piles or adjustable pedestals. Pedestals are superb for variable ground and low-height builds; they screw up or down to fine-tune levels without extra cutting.
   
4. Run fall away from the pool at 2 mm per metre so splashes never pond behind the boards; one of the simplest installation tips that pays off for decades.
   

3. Building a Code-Compliant Frame

Ledger and bearers

Bolt the ledger to the house or pool-house studs with 12 mm galvanised coach screws spaced 400 mm apart. Flash behind it to keep cladding dry.

Joists

Most composite decking suppliers recommend joists at 400 mm centres (450 mm max at ninety-degree board layout). Angled patterns need tighter spacing – Futurewood says 350 mm at 45°.

Lay joists perpendicular to the planned board direction. Double-up joists at deck board butt joints and where breaker boards will land.

Hardware

Use stainless-steel nails or structural screws and check every connection is at least 100 mm above finished ground to avoid perpetual damp.

4. Installation Tips: Laying Composite Decking Boards

• Acclimatise packs for 24 hours onsite so expansion is predictable.
  
• Set a starter clip along the outer rim joist; tap the first board in.
  
• Run boards full-length where possible. If you must butt-join, stagger joints across the deck for a natural look.
  
• Maintain a 5–6 mm side gap (clips usually dictate this) and a 3 mm end gap for boards under 3 m, widening slightly in the Deep South where winter temps dip lower.
  
• Trim curves: A jigsaw with a fine-tooth blade follows pool contours; template the curve with cardboard first.
  
• Face-screw last board if access prevents hidden clips. Pre-drill and countersink to avoid mushrooming.
  

These steps make installing composite decking boards straightforward and consistent with an inground pool.

5. Trimming, Fascia and In-Ground Pool Edge Detail

• Fascia boards hide joist ends and give a crisp shadow line. Mitre inside corners for a furniture-grade finish.
  
• Skirting in matching composite decking shuts out rodents under low decks.
  
• Coping break: Leave a 6 mm expansion gap between deck and pool coping stones, filling with flexible MS polymer sealant. This prevents heaving, cracking tiles and keeps the transition tidy in high-traffic pool areas.
  

Add glass or aluminium railing if the deck edge sits higher than 1 m above ground.

6. Safety Checks Before the First Splash

• Handrails or glass balustrades on any edge with a fall of 1 m or more must meet F4 load specs (0.75 kN horizontal).
  
• Gate self-closer: Test that it latches every time.
  
• Board traction: Hose the deck, walk barefoot, and note any slippery spots. Replace smoother boards or add traction strips if needed. Slip-resistant composites like MoistureShield or Millboard’s textured range test well around pools.
  

A reputable deck builder will document these checks in your handover pack.

7. Cleaning and Care

Composite decking may be low-maintenance, but it is not no-maintenance.

Task	Frequency	Tip
Light wash with garden hose	Monthly in summer	Soft-bristle broom plus mild dish soap lifts sunscreen residue.
Deep clean	Twice a year	Use a non-chlorine composite cleaner; rinse thoroughly.
Inspect fixings	Annually	Tighten any clips that have crept due to thermal cycling.
Re-test sealant gap	Every 2 years	Replace flexible joint if cracking appears.

8. What Will It Cost?

Recent NZ quotes put composite decking around pools between NZ $300 and $600 per square metre installed, depending on board quality and frame complexity. A 25 m² wrap-around deck could therefore range from roughly $7.5 k to $15 k. While upfront spend is higher than pine, you avoid the $400-plus annual bill for sanding, staining and splinter repairs, so breakeven arrives in roughly six seasons.

Frequently Asked Questions: Composite Decking Around In-Ground Pools

Is composite decking safe beside a chlorinated swimming pool?

Yes. Reputable composite decking brands encapsulate wood fibres in plastic resins that resist chemical attack and staining. Many composite deck may also include anti-fade pigments for our harsh UV.

How wide must the joist spacing be for angled board patterns?

Reduce spacing to 350 mm at 45° or 300 mm at 30° to stop bounce.

Do I need a building consent For Decks?

Not if the finished deck is below 1.5 m fall height. Still, council may ask for plans if the deck forms part of the pool barrier, so always confirm before ordering timber.

How do I remove sunscreen marks?

Use a pH-neutral deck cleaner and warm water. Avoid solvent-based products that can dull the surface.

Ready to Dive In?

A flawless pool deck starts with precise planning, code-smart framing and patient board laying. If you would rather swim than swing a hammer, our network of vetted craftsmen can help. Talk to NZ’s composite decking specialists today! Request a site visit and fixed-price quote, and you could be dipping your toes into a brand-new deck by next summer. Good luck with your composite decking installation, and enjoy years of relaxed outdoor living.