Brimstone Ash Decking

Being durable, stable and relatively knot free, Brimstone ash is a locally grown alternative to tropical hardwood decking.




VDEC 1 – 3


South of England

Brimstone Ash Decking Features

We used to sell tropical hardwood decking, but with a heavy heart. We didn’t really want to, but there was no locally grown alternative to match the visual appeal, hardness and above all durability of tropical hardwood timber.
Well, now we have one – Brimstone Ash, and we have stopped selling tropical hardwood decking. Brimstone is our new product and we create it with a clever technology called thermal modification. The process involves super heating English ash to 210° degrees which stabilises the wood, makes it durable and turns it a beautiful dark chocolate brown.
Thermally modified ash has been used for decking in the US for some time now and it is catching on fast across mainland Europe. Brimstone Ash is, however, the first British grown product on the market and we are very proud of that.
If you are considering using Ipe, Yellow Balau, Garapa of any of the other tropical hardwood decks, then consider this first. You can get the same performance with the knowledge that you are supporting local woodlands and without any of the sustainability worries attached to tropical wood.

Call us to discuss your project


Brimstone ash Decking from Vastern Timber

  • Thermally modified British ash
  • Sourced from legal and well-managed woodlands in England and Wales. GIB certified.
  • Supplied by Vastern Timber (
  • EN942:2007 J10
  • Finished thickness of 21mm
  • Overall finished widths of 95mm / 120mm / 140mm
  • Random lengths 1.5mt – 3.0mt+
  • Available in various profiles
  • Moisture content of 4 – 6%
  • Durability EN350-2 Very Durable. Class 1 (Above ground use only)
  • Supplied uncoated. Decking oil recommended



Thickness Overall Width Profiles available
21mm 95mm VDEC2, VDEC3
21mm 120mm VDEC2
21mm 140mm VDEC1, VDEC2
27mm 145mm VDEC4

1.5mt – 3.0mt+


Brimstone ash has a consistent chocolate brown colouring with a strong grain pattern. Decking boards may contain occasional small sound knots.

The modification process removes most natural extractives resulting in relatively consistent weathering, largely free of staining. Weathering to a grey colour occurs more quickly than for non-modified timber.

Durability (EN350-2)
Very durable. Class 1

Desired service life
Frequently wet 30 yrs* (This is heavily reliant on good design and installation)

*(Realistic service life as decking more likely to be 15 – 20yrs)

Movement class

Working properties
Brimstone is more brittle than untreated wood. Please take care when
cutting and fixing to prevent splitting. Pre-drilling and countersinking is essential.

563 Kg / Cm3

The modification process involves no chemicals and most natural chemicals in the wood are removed during the process. You can treat Brimstone as inert.


While the utmost care has been taken to provide accurate information, Vastern Timber shall not be held responsible for any consequences arising from any errors or omissions on this website nor for any damages resulting from the use of the information.

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