Getting ready to install a system for a friend. Will be putting a C8 in his house with most of the devices.
He has a barn/garage across the street. Needs a couple sensors there. There is a wifi access point there. So my thought is to put a second hub there and mesh to the main hub.
The barn is a metal building. There will have to be a door sensor on a shed just outside the back of the building.
I have a spare C5 that I no longer use. So thinking about using that in the barn. My concern is the radio strength with the metal walls and the outside sensor. Trying to keep his cost down at this time and thus the reason for using the C5 instead of buying another hub.
While metal walls are certainly an issue, there might be enough gaps in the eves or around doors or windows for the RF to get out.
I have put temperature sensors in a garage freezer. While you would think that the freezer would be a Faraday cage, somehow the signals manage to get through the door seal.
The issue is not so much the transmit strength of your hub, but the transmit strength of the sensor on the shed. One thing you can do is add a mains-powered repeater as close to the shed as possible. Of course, that requires having access to a power outlet.
Another option to consider for the shed is using a WiFi/Matter sensor rather than Zigbee or Z-wave. The Wifi Access point would communicate with the sensor. However, whether this is successful or not might depend on the capability of the access point. If this is an older device, it might not have the range of newer WiFI6, WiFI6e, and WiFi7 devices.
It is likely that you will need to do some experimenting with the location of your hub and repeaters to achieve a good mesh. Sometimes moving them just a few feet can make a big difference if there are obstacles to line of sight.
The first hub I owned was a C7, so I do not know much about the C5 hub. What I do know is that when I upgraded from C7 to C8 (with the external antennas), it greatly improved my connections. Nearly all my Z-wave devices were able to connect directly with the hub which is centrally located in a decent sized home with two floors and a basement. I recently upgraded to the C8 Pro to make my system more responsive. I know you are working within a budget, but if you choose Z-wave sensors in the barn, the C8 or C8Pro hub with their antennas might make things more stable.
The garage is about 40' long. The hub will have to be at the front, whereas the shed is outside the back. There are only 2 devices that have to go on that hub, the shed door and a motion detector in the garage.
I am putting a C8 in the house, but it would be an overkill to put one in the garage just for 2 devices.
That will probably be what I have to do if it doesn't work.
Problem with that is then I would need a thread border router. Or thread hub. It's my understanding that battery operated matter devices are thread. Not just matter and thus won't work directly without the tread hub.
Trying to maintain a stable Zigbee mesh with only two battery powered sensors and a hub might not be easy. Zigbee loves having multiple repeaters so it can find the best signal path.
You might be better off with Z-wave sensors. Z-wave utilizes the 900 Mhz band vs the 2.4 gHz band for Zigbee and WiFi. While Zigbee has a higher data rate, Z-wave has better transmission distance. Not having a C5 hub, I do not know how good the radio is on that hub. You might take a look at some of the posts on adding an external antenna to the C5 hub. It will take a little electronic know-how, but it is doable.
