My landscapers installed garden beds around my front yard(pics attached) but they have not put in any protection on the insides to act as a barrier to prevent any water damage. I was told by my friends that this needs to be done so I'm intending to dig out the soil and DIY it myself. None of my friends have been able to recall the name of the barrier. Any advice on what it is called and why is it needed or is it compulsory needed?
Welcome to the Bunnings Workshop community @siva26. It's wonderful to have you join us and many thanks for your question about garden beds.
Those appear to be treated pine sleepers that are suitable for in-ground use. As long as they are H4 treated, there is no need for an additional barrier to prevent water damage. Personally, I've never come across as sleepers that are not H4 treated. If you look at this article on How to build a raised garden bed by @Adam_W, you'll see that he only uses drainage matting, but this is to stop sediment escaping and not prevent water damage.
The area you've marked are treated pine sleepers, but what's the front wall made from? It appears to be lots of smaller pieces. Are they sleepers as well?
The only final question I'd raise is, are you going to be growing vegetables or herbs in this garden bed? As @Adam_W mentions in his article, "Any beds where food will be grown or where you are likely to have contact with the timber should be constructed from non-CCA treated timber.".
Please let me know if you have any questions.
Thank your for your quick reply.
Yes, it seems like they are H4 treated pines. I just checked with my landscapers to make sure. The ones that you have marked blue is also treated sleepers cut into small pieces for design.
I will only be having decorative flowers and no vegetables at all.
That's fantastic, then @siva26. There is nothing to worry about if they are H4 treated pine sleepers, as they will last for many years in-ground.
Thank you Mitchell! I really appreciate your reply and help. I can start planting now