What a fantastic sized shed! It looks like there is ample room for all the garden tools and yet not encroaching significantly on yard space. Was this the shed you used Absco Sheds 3.0 x 0.78 x 1.95m Ezislider Double Sliding Door Garden Shed Woodland Grey, as I'm sure you'll have plenty of members asking?
Many thanks for sharing your project, I'm sure it will inspire many to do the same.
The white stuff is lime. The soil beneath the shed was clayey so I used lime to stabilise the clay and give it a bit of strength. Cement is another alternative, but it can break up if the soil is too clayey.
Thank you @BrendanB . I have the same issue clay soil. Didn’t excavate enough so this lime advice will help heaps
Welcome to the Bunnings Workshop community @AdamDavies. It's great to have you join us and many thanks for your question.
Let me mention @BrendanB so they are notified of your question and to see if they have had any issues building directly against the fence.
We look forward to hearing about the projects around your house and garden and I trust you'll find loads of inspiration for them from with the community. Please let us know if you ever need any assistance with them or if you have something to share with us.
No issues building it directly against the fence. The structure is actually quite light and so you and someone else could build it off the fence and then move it against the fence.