Home > Companies > Outdoor Deck Company Ltd > Grad Deck System – Thermo-Ash

Decking system with Thermo-Ash timber boards on hidden fixing support rails and height adjustable pedestals.

Features and benefits:

  • Fixings are completely hidden, even between the boards.
  • Includes fast-fit clips, which cannot be dislodged once fitted.
  • Attractive appearance.
  • Support rails have industrial strength.
  • Boards can be removed with no damage (using specific tools - consult manufacturer for details).
  • Space-saving - can be installed to lower heights than traditional decking.
  • A matching cladding system is available - consult manufacturer for details.
  • Boards are free from grooves, with a convex surface – this prevents ‘cupping’ of the timber and eliminates water from pooling.
  • Quick, efficient installation - almost twice as fast as traditional methods.
  • Comes with a 25 year warranty.
  • Pedestal-based build-up height is from 62 mm.

Thermo-treated timber:

Timber which has been thermally modified using a computer controlled, kiln based process that preserves wood using heat and water. Wood is dry heated to around 130°C to remove all moisture, then steam heated to over 200°C and held at that temperature for several hours. Finally, it is water spray cooled to ensure a final moisture content of just 5%. It is:

  • Rich brown in colour.
  • Rot and mould resistant.
  • Lightweight to handle.

This product also has a low thermal conductivity.

After exposure to moisture and sunlight (and without any UV protectant oil) thermo-treated timbers will naturally weather down to a soft platinum-grey colour.

Related literature

The following content references this product:

Standard product features

Board size (w x t):

120 x 21 mm.

Board weight:

12.6 kg/m².



Please note that when specifying a decking rail, live load requirement and planned pedestal centres must be considered. All rails are 3.7 m long, with clips fitted at the factory.


Different variants are available depending on the height required. Without pedestals, the Grad system can be installed with build-up heights as low as just 40 mm. Consult manufacturer for details.

NBS Specification

NBS Create logo
This product is associated with the following NBS Create clause:
20-15-25/125 Deck system

NBS Specification

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This product is associated with the following NBS clauses:

Product specification

An important note about specifying



Outdoor Deck Company Ltd


+44 (0)20 8977 0820

Product reference

Grad Deck System – Thermo-Ash

Board length

[ ______ ]


 - Rail:
[Conventional timber joist]
Consult manufacturer for details.
[18 mm flat rail (aluminium)]
0.7 kg/lm.
[30 mm rail (aluminium)]
1.1 kg/lm.
[45 mm rail (aluminium)]
1.2 kg/lm.
[62 mm rail (aluminium)]
1.3 kg/lm.
 - Pedestal:
Consult manufacturer and insert requirements.
[Not required]

Manufacturer details

Unit 6,
Teddington Business Park,
Station Road,
Teddington, TW11 9BQ
Tel +44 (0)20 8977 0820
Fax +44 (0)20 8977 0825
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