Putting up drywall in my new house so getting closer to needed smoke detectors. I wanted to go Z-Wave, but unfortunately I can’t find any wired zwave detectors, so it looks like its going to need to be wifi. 
Anyone know of a open detector that I can talk to OpenHab locally with? I really would rather not use a close service.
Do you mean wired for power? If so, Popp makes Z-Wave smoke detectors that can run from main power through a DC converter. Popp told me that if they are powered this way during inclusion, they will behave as mains-powered devices and can relay Z-Wave as a result. I have a few here with adapters, but haven’t wired them up to confirm the engineer’s report.
Exactly what I am looking for, but looks like EU only and no Smoke / CO. (required in my town)
Off topic really, but if you are subject to a fire regulation that isn’t satisfied with battery operated sensors, how is the regulation going to handle sensors that depend on some external server to raise the alarm?
I know there are commercial wireless systems doing just that, but they are certified to one standard or another as a system. Regulations would normally call for some standard, OH isn’t certified for any purposes so far as I know.
Or do you need self-contained sensors with inbuilt sirens as well? (i.e. a local alarm is ensured regardless of what else might be triggered externally)
Have you seen this resource
http://products.z-wavealliance.org/regions/2/categories/19/products
I don’t think any of the products being considered fit that description. I certainly wouldn’t put anyone’s safety at risk by having a silent smoke/CO sensor that required a working Z-Wave or TCP/IP network to alert them to danger!
On the question of Popp being EU-only: You could get a EU-frequency Z-Wave dongle and a spare SBC to use EU-frequency Z-Wave devices, and tie it to your main openHAB instance using the MQTT event bus binding.
To address CO as well as smoke: I have two Nest Protects which appear to be working well and there are mains-powered versions. Reporting outside of range of sight and sound does require Internet connection, but there are ways to have redundant, battery-backed-up Internet links if it’s really important.