Although elm is now largely extinct in the British Isles due to Dutch Elm disease, Vastern Timber continues to maintain some of the largest stocks of logs and sawn planks in the country.
Elm is undoubtedly the most beautiful timber grown in our native forests. Its colour can range from dark purple to light green, with various hues of silver and brown in between. The grain can be wild and the cladding boards will contain various knots and burr clusters (cat’s paws), all creating a stunning finished product when used as cladding.
British elm cladding has long been used, especially in Wiltshire, where it was known as the Wiltshire weed. The uneven, but usually sound, edge of elm has made it a popular choice for waney-edge cladding.
Elm is a particularly unstable wood and prone to distortion so care should be taken not to expose the cladding boards to excessive heat, either before or soon after fitting.
Produced to comply with the harmonised standard for construction products regulation BSEN14915:2013 and to conform with BS8605-1:2014 External timber cladding: Method for specifying.
|Trade Name||Green elm (or fresh sawn elm)|
|Base timber||British elm (Red, wych, Dutch and hybrid all mixed)|
|Origin||Legal and well-managed forests in England and Scotland.|
|Intended use||External cladding|
|Appearance||Boards will range in colour from purple to green with wild irregular grain and regular sound knots.|
|Weathering||As the boards weather the colour will change to a silver-grey. As the elm dries out the boards will shrink and are likely to distort to some extent resulting in a rustic appearance. Elm does not tend to exude any extractives such as tannin.|
|Profiles||Sawn only. Feather-edge, square-edge and waney-edge|
|Lengths||Random. 1.5 – 2.5mt +|
|Moisture content||Wet. Beyond measurement.|
|Natural durability (EN350-2)||Non / slightly durable. Class 4 (Although only classed as slightly or non durable, elm lasts well untreated in cladding situations. With treatment elm is found in situ more than 50 years after installation).|
|Insect attack||The ambrosia beetle can attack the wet timber (30% moisture +). However, the beetle will die as soon as the wood dries to less than 30%. Re-infestation will not occur. Other dry wood will not be affected. Sapwood can be attacked by the powder post beetle (Lyctus spp).|
|Desired service life:(BS8417)||Occasionally wet 15 yrs (In practice 30yrs+)
Frequently wet <15 yrs
|Movement class||Large (Up to 10%)|
|Resistance to impact||Medium to high|
|Resistance to fixing||High. Pre-drilling recommended.|
|When to fix||Autumn / winter only. Definitely not during summer months.|
|Grading||Not graded to a BS standard. Generally rustic.|
|Working properties||Green elm is generally easy to work and takes fixings satisfactorily. Boards are likely to distort as they dry.|
|Extractives||Elm does not contain any reactive extractives such as tannin. We would still advise the use of stainless steel fixings.|
|Emission of formaldehyde (EN14915)||E1 (Not significant)|
|Reaction to fire (EN14915)||Euroclass F (Untested). D-s2, d0|
|Fire treatment||Not suitable|
|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.|