In general, you can put a patio heater under a gazebo, roof, or another type of awning as long as there’s enough clearance. Manufacturers’ instructions should include this information, but as a rough rule of thumb, you’ll need at least two (sometimes three) feet of clearance above a mushroom-style heater if it’s going to be used under a roof. Propane and gas heaters are not meant to be used indoors or in enclosed outdoor spaces, however. Some electric heaters can be used indoors or out.