I bought my house six years ago. It has charm, thick plaster walls, and wiring that predates most smart home standards. I wanted to automate lights, locks, and climate control without gutting the place. It took longer than expected. I made mistakes. Here is what I learned.
One of the first surprises came when I opened a switch box. No neutral wire. That killed half my shopping list. Many smart switches need a neutral to stay powered. I had to find switches that work without one. That narrowed the options. I also needed a hub that could handle Z-Wave and Zigbee because Wi-Fi devices alone would choke on the thick walls. I usually order from a site like zmartusa because they stock the harder-to-find Z-Wave switches and include technical specs that other retailers bury. That helped me pick the right parts without guessing.
No neutral? You still have options
Switches that work without a neutral exist. Lutron Caseta is the most popular choice. But Caseta uses its own radio, not Z-Wave. That means you need its bridge. If you want Z-Wave, your options shrink. Some manufacturers make Z-Wave switches that trick the circuit by leaking a small current through the load. They work with LED bulbs, but not all. I tried a few that flickered. One brand required a bypass capacitor behind the switch. That added complexity. The key is to buy from a supplier that lists the exact wiring requirements. I ended up using a mix of Caseta for the main lights and Z-Wave modules hidden behind existing switches for a few key loads.
Plaster and lathe block signals
My walls have wire mesh under the plaster. That mesh acts like a Faraday cage. Wi-Fi from the router barely reaches the bedroom. Zigbee devices struggled too. I had to put Z-Wave repeaters in every other room. Even then, some sensors would drop offline. The fix was to place the hub in a central hallway and use wired repeaters where possible. Smart bulbs work better because they act as repeaters themselves. But if you switch off the wall switch, the bulb loses power and the mesh breaks. I learned to avoid wall switches for lights that need to stay online. Instead I use smart bulbs with a constant power supply and a remote fob.
Choose a hub that does not depend on cloud
Old houses lose power more often than new builds. A cloud-dependent hub leaves you in the dark when the internet goes out. I started with a Wi-Fi hub that required an app and an account. The first thunderstorm knocked out my router. I could not turn on the porch light. I switched to a local hub that runs entirely on my network. Now my automations work even when the ISP is down. Z-Wave and Zigbee hubs that support local processing are worth the extra cost. Some even allow backup to a microSD card so you do not lose your settings after a crash.
Sensors: do not skimp on door/window sensors
Old houses have doors that warp with the seasons. The gap between the door and the frame changes. Cheap magnetic sensors often give false alerts when the door settles. I bought a batch of budget sensors. Half of them reported a window open every time the wind blew. I replaced them with Z-Wave plus sensors that have adjustable magnet spacing. These work better because the sensor and magnet can be further apart. I also placed sensors on the hinges side for some doors because the gap is more consistent there. It took trial and error. I now buy sensors from the same store where I got my switches because they carry a wider selection of mounting brackets.
Smart locks on old doors
Old doors are often thicker than modern ones. The standard backset for a deadbolt is usually correct, but the crossbore hole can be off center. I installed a smart lock on my front door. The latch did not align with the strike plate. I had to file the plate. Then the motor strained to throw the bolt in humid weather. I learned to look for locks that have an adjustable latch or come with multiple strike plates. Some smart locks also need a strong Wi-Fi signal to stay responsive. If your door is far from the router, consider a Z-Wave lock paired with a nearby repeater. That connection is more reliable than Bluetooth or direct Wi-Fi in my experience.