Will ST work as a pair to cover a larger house?

Considering ST as a home automation solution but have multiple floors, sub-level garage and two home floors above. Will ST communicate and share status or must multiple zones be created to support a whole home?

Do you mean two hubs? I don’t think you’d want to do that. The devices that communicate with ST create a mesh network, meaning they relay signals among themselves and to the hub. If your house is very large, you would mainly want to have enough devices relaying the signals (some devices are designed specifically to do that, you just plug them in). At least I think that’s how you’d deal with that. I live in a small apartment, so all my devices take very few hops to the hub.

@JDRoberts this is up your alley.

As far as I know the hubs do not connect to each other. Each area would have to be a separate zone. However, most devices also act as repeaters which will extend your network, covering your whole home.


This is really two separate questions: how much coverage can you get with a single hub, and what can you do if a single hub is not enough.

In most cases if it’s just one residential building, even a large multi floor Villa, one hub will be enough if it is placed centrally both horizontally and vertically providing the building is not constructed of concrete or Adobe. If it is constructed of materials that reduce the strength of wireless signals, then it becomes more challenging. The following thread (this is a clickable link) goes into more detail.

And this one:

If one hub is not enough, the SmartThings architecture does not support adding a second hub and coordinating them. You are limited to one hub per “location.” It is possible to define multiple locations in one building, such as one per floor, but it does require some duplicated efforts. Most of those details are discussed in an article in the community created wiki on automating an outbuilding. Even though that is somewhat different situation since it assumes there are two buildings, Many of the same technical issues apply.


The plugged in devices will relay signals within their appropriate band. There is a limit to the number of objects per system though. (1000’s for ZigBee or Z-Link) The hub is another matter, but I have seen that 300 is not a problem.

The limit for Z wave for any controller is 232 devices counting the hub itself.

In addition, there are known issues with both the IDE and the SmartThings mobile app once you get over 200 devices regardless of whether they are Z wave, zigbee or something else. There were actually two separate issues. One had to do with the maximum number of devices allowed per class (such as X number of switches) and the other had to do with the maximum total.

I know there was some expansion of this in May 2016, but I don’t remember the exact details. @johnconstantelo should know.

1 Like

Thanks Mark. I did mean two hubs, however I have since bought the ST, placed it in a central location within the house and installed light switches on Garage floor and ground floor. They are communicating just fine. So I was apparently worried for nothing.

1 Like

Thanks JDR, you have given me some really interesting information to chew on.
My house is under 4Ksqft and I repositioned my WIFI, hub and ST to a very central location before installing GE smart light switches. All seem to be communication very well from subfloor garage to the main floor.

Sounds good Glenn, I don’t expect to hit the device ceiling in my home. Don’t think my budget would handle it, so we’re safe there.

R, good point. The repeaters “are” propagating the network where I need coverage.