I love the idea as I have wanted to do something with the roof of my bird table for a long time. However, where do you find the water retentive matting and sedum matting, and can you just buy enough to fit a bird table or would I have to order a huge amount which would go to waste.
Alternatively, could I use some other materials that would do the job just as well? I have some sedums in a pot, so could I make my own matting in some way?