Composite Decking Boards: A Complete Guide
Composite decking is a modern alternative to traditional timber decking, combining the appearance of natural wood with the durability and low-maintenance performance of a wood-plastic composite material.
Whether you're creating a garden terrace, patio, balcony, outdoor seating area, walkway or commercial outdoor space, composite decking boards provide a practical and attractive surface that can be designed to complement both traditional and contemporary properties.
A complete composite decking system can include:
- Composite decking boards
- Composite edge and step boards
- Joining clips
- Starting clips
- Stainless steel decking screws
- Adjustable raisers / pedestals
- Supporting joists or subframe
- Finishing and installation accessories
The following guide explains the different components, their applications, benefits, installation methods and the options available when planning a composite decking project.
Main Uses of Composite Decking
Composite decking is suitable for a wide variety of residential and commercial applications.
Garden Decking
One of the most popular applications is creating a low-maintenance outdoor living area in the garden.
Composite decking can be used for:
- Garden patios
- Seating areas
- BBQ areas
- Outdoor dining spaces
- Areas around garden furniture
- Raised garden terraces
Balconies and Terraces
Composite decking can transform balconies, roof terraces and outdoor platforms into attractive, usable spaces.
Its clean appearance makes it particularly suitable for modern properties.
Poolside Areas
Composite boards can be used around swimming pools and outdoor leisure areas, subject to selecting a product suitable for the specific environment and following the manufacturer's installation requirements.
Walkways and Garden Paths
The boards can also be used to create attractive pedestrian walkways between different areas of a garden.
Commercial Applications
Composite decking is suitable for:
- Restaurants
- Hotels
- Holiday accommodation
- Outdoor seating areas
- Commercial terraces
- Apartment developments
- Office outdoor spaces
What Is Composite Decking?
Composite decking is manufactured from a combination of materials, typically including wood fibres and polymer, together with additives and colour pigments.
The result is a decking board designed to provide the visual character of timber while reducing some of the maintenance associated with traditional wooden decking.
The boards shown in your reference images feature a hollow multi-chamber construction.
This design can provide an excellent balance between:
- Structural performance
- Weight
- Material efficiency
- Ease of handling
- Long-term outdoor use
The outer surface features a realistic wood-grain texture, giving the boards a natural timber-inspired appearance.
Composite Decking Boards
The main decking board forms the visible walking surface.
Key Features
- Wood-effect surface
- Hollow multi-chamber construction
- Consistent dimensions
- Low-maintenance exterior
- Designed for outdoor applications
- Resistant to normal outdoor moisture exposure
- No regular painting or staining required
- Easy to combine with matching accessories
Composite Edge & Step Decking Boards
Composite edge boards, sometimes called finishing boards, fascia boards or step boards, are designed to create a clean finished appearance around the perimeter of a deck.
They are particularly useful for:
- Deck edges
- Steps
- Raised decking
- Staircases
- Platform edges
- Changes in decking level
Why Use an Edge Board?
Without a finishing board, the exposed ends of the decking structure can be visible.
An edge board provides a more professional appearance by covering and finishing the perimeter.
It can also be used to create a visually defined step or stair nosing.
Benefits of Composite Decking
Low Maintenance
One of the biggest advantages of composite decking is reduced maintenance compared with traditional timber decking.
There is generally no requirement for regular:
- Painting
- Staining
- Sealing
- Wood treatment
Routine cleaning helps keep the decking looking its best.
Timber-Look Appearance
Modern composite decking is designed to reproduce the appearance of natural wood.
The boards shown in your reference photographs have a pronounced wood-grain texture, giving the surface a realistic timber-inspired finish.
Durable Outdoor Surface
Composite decking is designed specifically for outdoor applications and can provide a durable surface for everyday foot traffic.
Resistant to Rot and Splitting
Unlike natural timber, composite decking does not suffer from biological decay in the same way as untreated wood.
However, correct installation and drainage remain essential for long-term performance.
Consistent Appearance
Composite boards provide a much more consistent profile and appearance than natural timber.
There are no natural knots, large cracks or irregular timber dimensions.
Easy to Clean
For normal dirt and debris, the decking surface can generally be cleaned with:
- A soft brush
- Water
- A suitable mild cleaning solution
Available Colours
Composite decking is available in a range of colours designed to suit different property styles.
Typical options may include:
Anthracite / Dark Grey and Black
A popular choice for modern homes and contemporary gardens.
Light Grey
Creates a bright, clean appearance and works well with modern landscaping.
Brown
A traditional timber-inspired option that works particularly well with natural landscaping.
Wood Brown / Teak Effect
Designed to reproduce the warmth of natural timber.
Other Colours
Depending on the product range, additional colours may be available.
Important: Colour names and exact shades can vary between manufacturers. Always use physical product samples when matching decking to an existing project.
Available Sizes
Composite decking dimensions vary between manufacturers.
A typical hollow decking board may be available in dimensions around:
150 × 25 mm
with lengths commonly available in several metre options.
For example:
- 2.9 m
- 3.0 m
- 3.6 m
- 4.0 m
- 4.8 m
- 5.0 m
- 6.0 m
These are example industry sizes rather than specifications for the particular boards. The exact width, thickness, length and permitted joist spacing should be confirmed from the product's technical data before installation.
Composite Decking Joining Clips
Joining clips, also known as hidden fixing clips or T-clips, are used to secure composite decking boards to the supporting joists.
The clip sits between adjacent boards, helping create a consistent gap while keeping the fixing system largely hidden from view.
Benefits
- Creates consistent board spacing
- Provides a clean appearance
- Reduces visible screw heads
- Helps secure boards to the subframe
- Speeds up installation
- Creates a professional finished deck
Starting Clips
Starting clips are used at the beginning of a decking installation.
They are normally fixed to the first supporting joist before the first decking board is positioned.
The board then engages with the starting clip, creating a secure and neat starting edge.
Advantages
- Clean installation
- Secure first board
- Consistent positioning
- Reduced visible fixings
- Professional edge finish
Starting clips should be compatible with the specific decking board profile.
Stainless Steel Decking Screws
Stainless steel screws are an important part of a quality composite decking installation.
Outdoor decking is exposed to rain, moisture and changing temperatures, so corrosion-resistant fixings are essential.
Stainless steel screws can provide:
- Excellent corrosion resistance
- Long-term outdoor performance
- Reliable fixing
- Clean appearance
- Compatibility with hidden fixing systems
For coastal or particularly demanding environments, the appropriate stainless-steel grade should be selected according to the manufacturer's recommendations.
Adjustable Raisers / Pedestals
Adjustable decking pedestals, also called adjustable raisers, deck supports or pedestal supports, are used to create a raised decking system above a suitable supporting surface.
They are particularly useful when installing decking over:
- Concrete
- Existing patios
- Roof terraces
- Balconies
- Flat hard surfaces
The adjustable height allows installers to create a level supporting structure even when the underlying surface has minor variations in level.
Benefits
- Adjustable installation height
- Helps achieve a level deck
- Useful for raised decking
- Creates space beneath the deck
- Can improve drainage beneath the decking structure
- Useful for installations over existing hard surfaces
Pedestals must be selected according to the required load capacity, height range and supporting joist system.
Complete Composite Decking System
A professional decking installation normally consists of several components working together.
Typical System
Composite decking board
↓
Joining / starting clips
↓
Supporting joists
↓
Adjustable pedestals or suitable foundation
↓
Existing concrete / patio / prepared ground
The exact construction depends on whether the deck is being installed directly over ground, on a concrete surface, or as a raised structure.
How to Install Composite Decking
Step 1 – Prepare the Area
Clear the installation area and ensure the supporting surface is stable and suitable.
For ground-level installations, prepare a suitable foundation that provides adequate drainage and stability.
For concrete installations, inspect the slab for cracks, movement and significant level variations.
Step 2 – Plan the Layout
Before fixing anything, determine:
- Decking direction
- Board lengths
- Joist positions
- Expansion gaps
- Edge details
- Step positions
- Drainage requirements
Good planning helps reduce waste and produces a cleaner finished result.
Step 3 – Install the Supporting Structure
Install the supporting joists according to the decking manufacturer's required spacing.
The subframe must be:
- Stable
- Level
- Properly supported
- Adequately drained
- Suitable for the expected load
Do not determine joist spacing from the board dimensions alone. Always follow the manufacturer's structural recommendations.
Step 4 – Install Adjustable Pedestals Where Required
For raised installations over concrete or other hard surfaces, position the adjustable pedestals beneath the supporting joists.
Adjust each pedestal until the subframe is level.
Ensure the support system is correctly positioned and does not obstruct required drainage.
Step 5 – Install Starting Clips
Fix the starting clips to the appropriate edge of the supporting structure.
Position them consistently so that the first composite board can be installed correctly.
Step 6 – Install the First Board
Place the first decking board into the starting clips.
Check:
- Alignment
- Board position
- Edge spacing
- Level
Secure it according to the manufacturer's recommended fixing method.
Step 7 – Install Joining Clips
Insert the joining clips into the board groove and secure them to the joists.
Position the next decking board against the clips.
Continue the process across the deck.
This creates a consistent gap between boards.
Step 8 – Secure the Decking
Continue installing:
Board → Clip → Board → Clip
until the full deck area is covered.
Do not overtighten fixings, as excessive tightening can damage the board or fixing system.
Step 9 – Finish the Edges
Install composite edge/step boards around exposed edges.
These provide a clean finished appearance and conceal the supporting structure.
They are especially important for:
- Raised decks
- Steps
- Stairs
- Platform edges
Step 10 – Final Inspection
Once installation is complete:
- Check all fixings
- Check board alignment
- Check expansion gaps
- Check edge boards
- Remove installation debris
- Clean the decking surface
The finished deck should have consistent board spacing and a clean, professional appearance.
Expansion & Installation Considerations
Composite decking is not installed in exactly the same way as traditional timber.
Temperature changes can cause composite boards to expand and contract.
Therefore, adequate expansion gaps should be provided according to the manufacturer's installation instructions.
Pay particular attention to:
- Board ends
- Walls
- Posts
- Edge boards
- Fixed structures
- Long continuous runs
Never assume a single expansion-gap measurement applies to every composite decking product.
Drainage
Good drainage is essential for any outdoor decking system.
Water should be able to escape from beneath the boards rather than remaining trapped around the subframe.
When installing over concrete or patios, consider:
- Existing falls
- Drainage channels
- Pedestal positioning
- Subframe ventilation
- Water flow beneath the deck
A raised pedestal system can be particularly useful where maintaining drainage beneath the deck is important.
Composite Decking Maintenance
One of the biggest advantages of composite decking is its relatively simple maintenance requirements.
Regular Cleaning
Remove:
- Leaves
- Dirt
- Mud
- Food debris
- Organic matter
using a soft brush and suitable cleaning method.
Avoid
Avoid harsh chemicals, aggressive abrasive cleaning and unsuitable pressure-washing techniques unless specifically approved by the decking manufacturer.
Always test cleaning products in an inconspicuous area first.
Composite Decking vs Traditional Timber
| Feature | Composite Decking | Traditional Timber |
|---|---|---|
| Wood appearance | Yes | Yes |
| Regular staining | Generally not required | Usually required |
| Painting | Generally not required | May be required |
| Rot resistance | High | Depends on timber/treatment |
| Consistency | High | Natural variations |
| Maintenance | Low | Moderate/high |
| Installation | Clip/fixing system | Screwed fixing |
| Colour options | Multiple | Natural/stained |
| Outdoor use | Designed for it | Depends on timber |
| Appearance | Modern wood effect | Natural wood |
Why Choose a Complete Composite Decking System?
Buying the decking boards together with compatible installation accessories has several advantages.
A complete system allows you to match:
- Boards
- Edge boards
- Joining clips
- Starting clips
- Screws
- Pedestals
- Supporting structure
Using compatible components can make installation easier and help ensure that the fixing system works correctly with the board profile.
Recommended Applications
Composite decking is an excellent option for homeowners and contractors looking to create:
Residential
- Garden decking
- Patio areas
- Raised terraces
- Garden steps
- Outdoor dining areas
- BBQ areas
- Balcony decking
Commercial
- Restaurant terraces
- Hotel outdoor areas
- Apartment balconies
- Holiday homes
- Outdoor seating areas
- Commercial walkways