Not sure if it's possible in 4, but in 2 I build a little hut where my outdoor grill will go, complete with floor (usually stone or tile). The hut then gets an alarm and sprinkler, which will install because they are inside a hut. Sometimes I remove the extra structure, sometimes add a large arch. Even if a grill does catch fire, I've got double protection. I hate loosing any sims, and have been known to cheat code my way to the phone to grimmy and enough $ to pay the fee for a full resurrection. Again this is in 2.