Green treated wood for raised beds

owen.booler

Hi I am going to be building a compost bin and raised beds, I bought for the compost bin some cheap decking boards that I thought would be ideal and seen some plans on youtube on how to do it, however I am concerned with the treatment of the wood and whether it could be harmful. The wood seems to be treated using autoclave with a chemical called Impralit KDS which contains Cupric Carbonate, Boric acid and Didecylpolyoethylammoniumborate 

Does anyone have any experience with this? And am I ok to use this wood? 

Thanks for any help

Owen

K67

Are you based in the UK?

Fairygirl

I think 'cheap' decking boards may not last very long, regardless of what they're treated with or not. 
It'll depend on where you are, and what the climate and conditions are like too. Exterior ply or decent fencing timber will be better. 

nick615

As always, the question is whether or not the need for raised beds is actual or fashion.  If the decision is irreversible, and you intend to make them a regular feature of the garden, the only sensible material is concrete 'boards' or paving slabs that will last more or less for ever.  Dearer to start with but cheaper in the long run, and they avoid all the mess when replacing timber and the soil spills on to the gravel paths.

owen.booler

K67 said:

Are you based in the UK?

Yes I am! Thanks 

Obelixx

If you build them a sturdy support frame and attach them well they'll be fine.    If you're going up 2 or 3 or more levels of board I would advise lining the insides with black plastic stapled on.  This will have a dual role - protecting the wood from moisture form the soil and preventing any chemicals leaching into the soil.

If you're just doing one layer then I suggest you make a mixture of 1 litre of light olive oil (for cooking, not extra virgin) and the juice of one lemon and brush that on the wood.   leave to dry a day or two and then build.  It will provide a barrier and extend the life of the wood.

Fairygirl

My raised beds are made with good quality fencing timber, lined as @Obelixx describes.
They still look as new - 7 years on. Posts concreted in for the corners. I also have a 'coping' round them as they're decorative, not just veg beds.
The ones I made in my previous garden [ nearby] are all still there too. They were done with exterior ply, lined, and faced with decking to match our deck, as the whole thing was on a slope and we terraced it for planting. That was heavy duty timber though. Cheap stuff is a waste of money. 
Making borders when dealing with heavy clay, compacted ground covered with gravel and slabs is very difficult to change unless you have a digger, or nothing else to do all day, for months. Raised beds provide planting at a good level too. They're also useful if you have a lot of rainfall, as they drain better.