Building a raised bed

bartg

Hi. I'm thinking of using the wood from a small garden shed I bought from B&Q (some time after 2004) to make a raised vegetable bed. I know I should be using materials which would be more suitable for a project like this but we're having to watch the pennies at the moment. My question today is - Is the wood from a shed likely to be treated with chemicals which makes this a bad idea? I can't get hold of anyone at B&Q to ask the question. Can anyone help please? Thanks.

Fairygirl

If you line it [and you'll need to anyway ] it'll be fine.

You can use old compost bags or similar for doing that. 

bartg

Thanks for the quick response - much appreciated. I'm planning to line it with a landscape fabric which is breathable and will allow moisture through.  Will that do?

andyrudd15

I've just read your post and I'm in the process of taking out a raised bed made of oak sleepers. I chose oak because I thought they'd last a long time. I even lined the back of them with damp proof membrane as an extra measure but they still rotted.

I have learnt that timber which is used above ground is treated with a different treatment than timber which is going to come into contact with soil so although your old shed is treated it's unlikely to last a long time if it's used as a raised bed. I'm sorry to be the bearer of bad news.

On a happier note, I used to rent an allotment and I decided to have timber beds in a chequerboard arrangement. The timber posts were stood for a couple of weeks in creasote before knocking them into the ground. Whereas the timber boards, which were pretreated, just had a coat of creosote before fitting them. Years later when I gave the allotment up, the next renter didn't want to have the beds so I had to remove the all. Now for the good news. Although some of the boards were a bit rotten the posts could be used again because the treatment had done the trick. Also, using creasote didn't seem to effect the plants.
I hope some of what I have said will help. What I have decided is that timber is not brilliant outside unless it is very well protected from the elements. 

Fairygirl

Landscape fabric isn't any use. The fact that it's porous is the problem.
My raised beds are all made with heavy fencing timber, attached to concreted in posts, and they're lined with heavy duty plastic and all treated each year. They also sit on gravel, which helps, and are for decorative planting - not veg, and have a coping round the top which also helps protect them. 
Your shed obviously won't be particularly brilliant, but it'll do for a few years until you get something better. 

Lizzie27

We used old fence boards and just repainted them. Didn't line them with anything. They lasted about 10 years half sunk into the ground before they really rotted. Do what Fairygirl suggests and line them with whatever plastic you can lay your hands, stapled on is good and have a go.