Decking guide
Decking Materials Checklist
Everything to consider before starting a garden deck—from framing timber and boards to ground preparation, fixings and finishing materials.
Order the whole job
Avoid the forgotten-item trip
A decking order is more than a stack of boards. You also need the frame, support system, exterior fixings, ground-preparation materials and finishing pieces that suit the exact deck design.
Do these first
Four decisions before buying materials
These choices affect nearly every quantity on the order.
Measure the footprint
Record the overall length, width, finished height and any changes in level.
Choose the board type
Timber and composite systems can require different joist centres and fixings.
Plan the board direction
The direction and pattern affect board lengths, cuts, joints and waste.
Choose the support method
Ground-level and raised decks need different posts, pads, feet and framing.
Useful rule: Do not order boards until the frame layout and board-joint positions have been planned.
The structure
Frame and support materials
The frame carries the deck and determines how solid it feels. Use structural timber and exterior-grade fixings that suit the size, height and exposure of the finished deck.
- Pressure-treated outer-frame timber
- Pressure-treated decking joists
- Posts, deck feet, pads or suitable supports
- Joist hangers and structural brackets
- Exterior structural screws, bolts or coach screws
- Noggins or blocking where the frame needs restraint
- End-grain timber treatment for fresh cuts
The visible finish
Boards, fixings and trims
Calculate boards using their effective installed coverage rather than nominal width alone. Include the intended gaps, board length, cutting pattern and an allowance for waste.
- Timber or composite decking boards
- Correct decking screws or approved hidden clips
- Starter and finishing clips for composite systems
- Fascia boards to cover exposed frame edges
- Corner trims or end caps where required
- Decking stain, oil or preservative for timber
- Balustrade components for raised or enclosed areas
Below the deck
Ground preparation essentials
Good drainage and stable support help protect the frame and stop the finished deck moving as the ground becomes wet or dry.
Weed membrane
Helps limit weed growth while still allowing water to pass through.
Drainage aggregate
Gravel can help keep moisture and mud away from low-level timber.
Solid supports
Use suitable pads, blocks, feet or foundations for the chosen design.
Airflow space
Leave room for ventilation rather than boxing damp timber in tightly.
Order in the right sequence
A practical decking buying timeline
Planning in this order reduces guesswork and makes it easier to build an accurate materials list.
Measure
Confirm the footprint, finished height and any steps or awkward shapes.
Design the frame
Set joist centres, support points and board-joint locations.
Calculate boards
Use board coverage, chosen lengths, layout and a sensible waste allowance.
Add the small items
Count hangers, clips, screws, treatments, membrane and trims.
Request a quote
Send the full list together so the complete job can be checked and priced.
Save this list
Complete decking checklist
The full list is split into smaller groups. Open only the section you are working on.
Start with the frame, then check the surface, ground preparation and tools.
Frame and supports 7 structural items
- Outer-frame timber
- Internal joists
- Posts, pads, feet or support blocks
- Joist hangers and brackets
- Structural frame fixings
- Noggins and board-joint supports
- End-grain treatment for cut timber
Deck surface and finish 5 visible finishing items
- Decking boards
- Decking screws or hidden clips
- Fascia boards and trims
- Timber treatment or composite end caps
- Balustrade materials where required
Ground preparation 3 items below the deck
- Weed membrane
- Drainage aggregate
- Suitable base or foundation materials
Measure and set out 4 layout essentials
- Tape measure and long straightedge
- String line and marking equipment
- Spirit level or laser level
- Carpenter’s square
Cut, fix and protect 6 tools and safety items
- Suitable saw and blades
- Drill, impact driver and bits
- Board spacers where required
- Shovel, rake and preparation tools
- Personal protective equipment
- Manufacturer’s installation instructions
Useful links
Build the full decking order
Find the main materials, estimate quantities and send the whole job through for a quote.
Common questions
Decking materials FAQ
How do I calculate how many decking boards I need?
Start with the finished deck dimensions, then calculate using the board’s installed coverage, selected length, layout and waste allowance. The Canvey Supply decking calculator provides a useful starting estimate.
What timber should I use for a decking frame?
Use pressure-treated structural timber that is suitable for the deck design and expected exposure. Raised, heavily loaded or unusual structures may need a professionally specified frame.
Do I need weed membrane beneath decking?
Weed membrane is commonly used beneath ground-level garden decks. It should be installed without creating a waterproof basin that traps water around the supports or timber.
Can I build decking directly onto soil?
The frame should have stable, well-drained support rather than resting loosely on wet or moving soil. The correct foundation depends on the deck height, ground conditions and structural design.
How much extra decking should I order for waste?
Waste depends on the deck shape, board lengths, laying direction and number of joints. Simple rectangular decks usually waste less than diagonal or detailed layouts, so calculate from the actual cutting plan.
Can timber and composite decking use the same fixings?
Not always. Timber is commonly face-fixed with suitable decking screws, while composite systems may use product-specific clips, screws and starter components. Follow the board manufacturer’s instructions.
Where can I check decking joist spacing?
Read our decking joist spacing guide before finalising the frame quantities.
Got the measurements but not the full list?
Send us the deck size and planned board type. We can help price the decking, treated timber, aggregates, fixings and finishing materials together.
