Technical Spec

Deck25 Technical Information
Normal Raised Deck
     Gaps between boards
 (  when laid Side by side )
     Gaps between boards
 ( End to end -Butt joints )
     Perimeter Gaps
Expansion Gaps must be created when installing Deck25 composite decking.
Leave 5 mm gaps between boards when layed side by side.
Leave 5 mm gaps between ends of boards when joining end to end joints ( butt joints )
Leave 8mm - 10mm gaps between deck boards and perimeter material:
Create 8mm - 10mm gap between
deck board and brickwork
deck board and stone
deck board and Masonary
deck board and steel
deck board and glass
deck board and fence material







Deck25 Grooved & Woodgrain




    Joist spacing

Joists must be spaced no more  than 300mm centre to centre
(250mm spacing between joists)

Deck25 Grooved & Woodgrain

   Airflow in
Standard raised Decks
Special Consideration
Sunken, Enclosed, Roof  
Terrace and Roof Garden Decks require special consideration

Ensure Adequate Airflow
Ensure Adequate Airflow
Elevate Deck Frame above roof surface using Rubber Packers


 All Deck25 Composite, Softwood and Hardwood Decks require good Airflow through the substructure ie: Air must flow freely around The timber components that make up the supporting frame.

Good Airflow will protect your deck and maximise it's operational life

Standard Raised Deck. Airflow is achieved through the sides of the deck. Should the perimeter be closed in ( fully skirted ) It is important to install 100mm - 150mm air vents on opposite sides of the deck, contained within the skirt. The General  rule for a closed in Deck is to install 2no. air vents for every 12m2 of Deck surface area



Sunken and enclosed Decks

These are situations where air vents cannot be installed in the sides. 









This is achieved by installing air vents in the surface of the perimeter deck boards. Rectangular strip vents or circular air vents of 80mm - 100mm diameter should be installed on opposite sides. The general rule applies: Install 2no. air vents for every 10m2 of deck surface area. Air vents chosen should be made from plastic, Stainless steel or GRP.



 please note:

Where airflow is further restricted eg High wall around deck or solid panel safety barrier  system ( glass, steel or polycarbonate), this will also inhibit airflow.  It is good practice to increase gapping between deck boards from 5mm to 7mm to assist evaporation of water from the deck frame cavity. This is particularly important when decking over a flat or near flat roof.





Ensure that the supporting Deck Frame is elevated above the roof membrane using rubber packers, rubber blocks or rubber shoes.

Minimum clearance between the bottom of the timber joist (frame) and the roof membrane /surface should be 25mm. The more the better.


Deck25 Grooved & Woodgrain

Rubber Packers are used for the
following reasons:
Rubber packers will not pierce the roof membrane
Rubber packers distribute weight more evenly across a near flat roof.
Rubber packers cushion impact from Movement on the deck above. 
Rubber packers will not rot.
Rubber packers will not  conduct water up into the timber framework through capillary action.
Colours Available
Deck25 Grooved
Deck25 Woodgrain
Dark Brown
Medium Brown
Silver Grey
Designer Black
Atlantic Grey
Coverage ( laid )
Weight per m2 ( laid )
Deck25 Grooved
Deck25 Woodgrain
Deck25 Grooved and Woodgrain
 7.1m per m2 laid
 7.0m per m2 laid
 23kg per m2


Dimensions of Boards
Deck25 Grooved
Deck25 Woodgrain
25mm x 137mm x 4.88m
25mm x 140mm x 4.88m
Deck25 Technical Specifications
Mechanical Property
Test Method
Tensile Strength
BS2782: Part3, method 320C
11.3 Mpa
2.1% Elongation
Flexural Modulus
ISO 178 Span 150mm
4181 Mpa
Flexural Strength
ISO 178 Span 150mm
31.5 Mpa
Impact notched
BS2782: Part3, method 359
8.4 KJ/m²
Impact un-notched
BS2782: Part3, method 359
Water Absorption
ASTM D1037
Coefficient of Expansion
Across Length
Screw retention
(composite decking screw)
Compared to Red Cedar
76% greater
Nail retention
(5mm ring shank)
Compared to Red Cedar
18% greater
Specific Gravity
1.1 +/- 0.05
Deck25 Grooved slip resistance
HSE guidelines
(4S rubber test)
Perpendicular to groove (dry)
Perpendicular to groove (wet)
Extremely low potential for slip (SRV=68)
Low potential for slip
Deck25 Woodgrain
slip resistance
Perpendicular to board (dry)
Perpendicular to board (wet)
Extremely low potential for slip Co-efficient 0.88
Extremely low potential for slip Co-efficient 0.96
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