Building a garden room can vary in time depending on the specifics of your project.
From my personal experience, the planning stage took longer than I had anticipated due to the design back-and-forth, securing permits, and revisions. On average, you might expect around two to three months for simpler designs, while custom or larger projects could take longer.
The building phase itself usually flew by, surprising me with its efficiency – just a few weeks. Speed largely depends on the complexity of the design and the weather.
Sharing from a friend's story, unexpected hiccups, like material shortages or unpredictable weather, played a role in extending timelines, so it’s wise to factor in some flexibility.
As I was looking into it, I found a useful page that could be worth your time.
Come to think of it, ensuring constant communication with the builder can help foresee and address potential delays.