Will the cellular communicator even work inside a metal building, or can an external antenna be connected?
Building will be divided with steel panel walls into 3 sections.
Shop will be insulated, but no a/c or heat. It will be used for welding. 20′ ceilings. Is there a smoke/fire/heat/rate-of-rise sensor that would hold up in that environment and be reliable?
There are a lot of big concerns in this case, and I think you will find a lot of difficulty overall trying to implement a wireless system in this environment.
The IQ Panel 2 and the wireless sensors it uses are typically intended for interior use and a regulated temperature environment. Steel walls will devour wireless sensor signals, and from your description, it sounds like the sensors would be directly mounted to metal as well, and in such an environment I would expect a ton of signal errors.
In an entirely metal building, especially if cell service is spotty already, an internal cell antenna in a panel will possibly receive very poor signal.
PIR Motion detectors, unless specifically made for outdoor use, should not be used in an environment where temperature is not regulated.
Overall I would say an all-in-one panel and wireless sensors would not be a good choice for such an environment.
Considering you are constructing this building, I would recommend running cabling to utilize wired sensors in the space. All sensors should likely be wired. This will resolve more than one issue, and give you options for outdoor motion detectors should you wish to implement them. Lots of wired sensors exist that are intended for this type of installation, as opposed to very few wireless options, and in the case of GE 319.5 which Qolsys uses, there are pretty much no wireless sensors that I can think of which would be very well suited to this.
The wired sensors can then be used with an Alarm.com compatible traditional panel, like the Concord 4, or you could connect them to a Hardwire 16, installed close to the IQ Panel location should you opt for the all-in-one panel.
For the space, I would recommend a wired panel. One of the reasons to use something like the Concord 4 is that with the Concord, the cellular module is a separate board, wired to the main panel, not integrated. The module and its antenna location can be adjusted for optimal signaling.
We have tried using external powered cell antennae in the past with 2GIG panels, with mixed results. We have not used one with the Concord 4 modules. Generally I would expect improvement in signal, but powered antennae are pricey and I think getting the antenna outside will do as much or more to improve quality.
Shop will be insulated, but no a/c or heat. It will be used for welding. 20′ ceilings. Is there a smoke/fire/heat/rate-of-rise sensor that would hold up in that environment and be reliable?
For fire detection, a high temperature rate of rise detector is probably best in that environment. A good solution might be something like this. This could only be used with a wired panel.
I’d like to have motion sensors, but have had a problem in current shop with the occasional bird that gets inside thru the bay doors when I am working, then get’s locked up inside, eventually setting off a motion detector. Had a bat one time. Is there anything to do to make sensors bird-proof? Any other type motion sensor (laser, pressure pads, etc) that might be of benefit?
For an outdoor motion detector, this may be a good option. Outdoor detectors are designed to limit false activation.
Or you could use a photoelectric beam sensor like this.