For a first green shed roof i would recommend that you start off relatively small.
Green roof system for shed.
When saturated these layers can weigh in at more than 100kg per square metre or 20lbs per square foot.
There are some things you need to check before building but the job is not very difficult.
Waterproof first a layer of waterproofing needs to be added to your shed or garage.
Check that your shed is strong enough to take such weight and remember that the walls will also play a large part in bearing the load.
Building a green roof on your shed is a way to add interest to the shed and produce a new area to cultivate.
For plants to flourish on a green roof they will need moisture and drainage which means soil and a sturdy framework to keep it in place.
You will also need to make sure that your shed s roof is waterproof.
Even a flat roof should have some pitch so that it sheds water toward gutters.
Green roofs are made up of several layers typically a waterproof root barrier layer to protect the roof a drainage layer water retention mat then the growing medium and vegetation.
For a green roof installation that pitch should be at least inch per foot of run.
Enough to support the roof build up which comprised.
Ideally a green roof will go on a slope up to 10 but if it s on a slope over 20 make sure you have a frame to stop the green roof from slipping.
For this shed i used 3x2 softwood timbers at 600mm 2 ctrs which spanned 1 2m 4 with an 18mm 3 4 plywood deck.