Detached garage fire detection

I put a temp sensor in my extremely detached garage to detect a potential fire because my research indicated that smoke detectors often false-positive in garages. However, the “alert me when” smartapp will only send a temperature-related alert when I’m not present. I need to be alerted when I’m present. Is there any such app? Secondly, should I really be using a smoke detector? If so, is there a zigbee or zwave sensor that works with smartthings?

Create a custom alert in smart home monitor, I use it to tell me if my kids’ room is too warm or too cold. This seems like a bad idea for alerting you to a fire, btw, unless it’s like a backup to a backup to something that should work reliably.

First alert makes a z-wave smoke and co detector called zcombo.