Accoya Lumber

[Bernhard]

Hi all,

Starting to make plans for a greenhouse (~16 x 24ft). At first I was looking only at extruded aluminum frame greenhouse for obvious reasons : no rust, lumber was not considered due to instability, and rot and the genral poor quality of lumber available. BUT then I stumbled accross Accoya lumber ( Accoya | Acetylated Wood | Modified Wood, treated wood, Accoya). Basically they have a process to acetylate all remaining free hydroxyl groups thereby preventing water absoprtion and rot. This type of wood treatment is used in Europe (it is environmentallt friendly, no toxity etc), but it is also imported to the US (i.e Rex Hardwoods in Virgina has it).
So here is the question: Has anyone used this product or seen it used?
TIA
Bernhard

 

[mdbuntyn]

I don't remember if Shannon has any experience working with accoya, but it is discussed in this podcast episode:

https://www.lumberupdate.com/53-modified-woods/

 

[jlwest]

We used to make them out of PVC pipe curved like a quonset house covered in plastic. Ours was 14 x 35. Needed new plastic every year. Cheap and it worked.

 

[danceswithwindows]

Good friend of mine in Ireland worked with it a lot as an exterior facade material. He also covered it a lot as part of his degree in wood science. Seems like great stuff - supposedly it’s easy to work with as the base material is a relatively soft wood. The non rot and stability properties are also well documented.

If you are in Raleigh, they have a limited supply of it at capitol city lumber.

I’d love to give it a try on a small project!

 

[Bernhard]

Hi Matt and @dancewithwindows,
Thanks for the additional info and leads. As for the base wood, I think the process only works for softwoods, but I am not sure.
Accoya has a 50yr warranty so it should last as long as I need it. One question I have is the acetylation. Based on the info on the web site they do you acetic anhydride. What I don't quite understand is the stability. It appears that this bond should be fairly easy to hydrolize under the right condition back to free hydroxyls and acetic acid.

I will contacte Capital City lumber on Monday to see what they have and possibly get a small amount to play with.

 

[Canuck]

Checking their website, I am reading $13.25 - $14.15 a bdft!

https://www.capitolcitylumber.com/product-category/lumber/accoya-sustainable-wood/

 

[cyclopentadiene]

Acetic anhydride reacts with the cellulose in the wood to form cellulose acetate. The esters are relatively stable but this bond is hydrolyzed by acid or base. In addition, it is photodegradable upon exposure to sunlight. This is a surface phenomenon and should as the claim states last for decades.
The EU has a proposed ban on single use plastics which cellulose acetate is considered. I am not sure if includes this wood treatment but is a huge issue for Eastman Chemical in Kingsport Tennessee as this chemical is 60-70% of their revenue and this is one of the largest chemical manufacturing facilities in the USA. They are also one of the worlds largest producers of acetic anhydride worldwide