I traded up last year to a 15 year old detached house. I was busy all winter fixing up the inside. When the weather got better I started spending some time in the back garden trying to tame the wilderness. To my dismay I have "discovered" my neighbour's boiler. They have a block built shed on the boundary which houses their boiler. It has a pitched roof and the boiler chimney is on the side facing into my garden. Their heating seems to be on an awful lot. When I am in the garden and it kicks in it is very noisy. Now that I am aware of it I am hearing it all the time even when I am in the house! There is a retaining wall between the gardens. What are my options? Can I build on this wall and screen with planting? Are there any plants known for their noise absorbing properties? I am annoyed with myself for not spotting it during the buying process. Garden was very overgrown with large trees and obviously it was never on during multiple viewings as we never heard it! I will admit that I am sensitive to noise but this is seriously affecting my ability to enjoy my garden!