Hi @Nikbrad. While the Ring Alarm Home Security System is designed to be for in-home and indoor use only, it's possible that a door sensor could reach as far as your shed. The devices communicate on a Z-wave network that the Alarm Base Station creates, and it can talk to other devices connected to the Base from up to 250 ft away, open air. This does not account for inference such as walls and appliances.
Therefore, if your shed is more than 250 ft away from your Base Station, you will want to look into getting a Range Extender, or two. It's best to play around with it and see if the sensor can stay online, connected, and register its open/closed states when placed in your shed. If you're able to achieve this through some testing, then you'll be all set!
I have had a door contact sensor in my shed that is 30 ft from my house (Seattle area) for over a year and 2 winters (mind you it doesn't get that cold here) with no issues other than battery drain because of the cold/unheated space. No disconnects at all