soundproof garden room

[1805]

It's a long shot I know, but does anyone have experience with this?
I am looking at the cheapest possible way to create a 6m x 3m room in the garden, split into a music room (soundproofed) and a small utility room big enough for a washer and dryer.

I'm going round in circles. I've looked at bespoke studios (££££££), sheds that would need soundproofing (££?), shipping containers that would also need soundproofing.(£££?)
Any other ideas? Has anyone actually done this?

It’s quite simple but not cheap, I created a cinema room in my house and the process will be the same, sound proof insulation minimum 75mm then 40mm acoustic foam, you could the use acoustic plasterboard if you really want to go to town, your soundproofing requirements will be dictated by how close the shed is to the neighbours, obviously the issue with a shed is the walls are very thin to start with so very little noise barrier, I would suggest insulate between the joists using Knauft acoustic insulation boards or rock wool first then setup your drum kit and see how much noise you’re getting outside, and then decide if you need to insulate further