I took a picture of our garden shed, and I was thinking about what a garden shed is called in French. I've heard at least three expressions: (1) un abri de jardin, meaning a garden "shelter"; (2) une cabane de jardin, meaning a "cabin" or "hut"; or (3) un cabanon de jardin, meaning a slightly larger construction.
I plugged all three of those expressions into a Google image search, and I got basically the same photos each time. I guess abri, or shelter, is the best term. A bus shelter, for example, can be called un abribus — which turns out to be a brand name.
Then I noticed a web page showing the abri or cabanon de jardin shown above. Wow. What would you do with such a structure? Why would you want one? I guess I just don't get it. Add on a tiny kitchen (un coin cuisine) and a small shower room (une salle d'eau) and you've got a nice Paris apartment.
Meanwhile, here's a photo of our cabane de jardin. It needs refurbishing, but it serves the purpose, which is sheltering the lawn mower, the rototiller, a couple of wheelbarrows, and various shovels and rakes. Not to mention a lot of spiders.