Welcome to my first Instructable!

Background:
I've been learning more and more about home automation and have opted to use z-wave devices for most of my system. With the addition of the SQ Blaster and SQ Remote iPad app I've been able to make a wonderful remote control system for my home.

The garage door opener became a bit more of an urgent issue recently when a neighbor called and told me that my garage door had been left open all day. With this project in combination with a door/window sensor I'll be able to keep myself apprised of such oversights in the future and be able to take care of it from anywhere in the world!

Giving credit where credit's due:
Please note that this concept was not my original idea. I Googled "z-wave garage door opener" and came across a video of someone else's very similar concoction. My only contribution is making this instructalbe and using my electromechanical experience to streamline the final device.

Disclaimer:
I accept no responsibility for any damages to persons or property caused by following this Instructable. Please use caution any time you handle soldering irons, interact with high voltages and climb ladders! ;-)

Required materials:
Z-wave plug-in appliance switch (I used an Intermatic HA02C, $27 on eBay)
120v relay (I used Radio Shack model #275-217, $9)
Project Enclosure (I used Radio Shack model 270-1801, $3)
Power cord (Mine was cut off a dead fan)
Approx. 3' of 2-conductor wire (any small guage, 20-26AWG, will do)
Solder
Double-sided foam tape

Recommended materials:
Z-wave door/window sensor to indicate DOOR CLOSED state (not shown in this instructable).

I've purchased a few "Aeon Labs Z-Wave Magnetic Door / Window Sensors" from eBay (not yet received).

Tip:
As most garage doors are metallic and I've read that the metals often interfere with the reliability of the magnetic properties of the sensor, I'll be mounting my sensor and it's triggering magnet to plexiglas brackets mounted to the door and rails to lift it away from the ferrous metals. I just wanted to pass on this tip to save you some troubleshooting time in case you come across this problem in your own implementation.

Step 1: Building It...

As you can see, the assembly is very straightforward.

I drilled two small holes in the side of the box and used an x-acto knife to cut the holes into an oval shaped like the power cord so it would fit with precision.

The power cord was cut short enough to eliminate excess wire dangling from the final assembly but long enough to keep the wire from being too tight.

Feed the power cord through the hole, then split the strands (or strip back the jacket of you use a jacketed cord) about 1" from the end. Strip the conductors about 1/4" and tin with solder. Solder the conductors across the relay coil. (If you're unfamiliar with relays, don't worry about polarity. As this is AC and coils are not polarized you can connect in any order.)

Drill a small hole in the lid of the box and feed through your smaller remote wire. As with the power cord, split the conductors about 1", strip 1/4" and tin. Solder across the Normally Open (NO) contacts. This relay has two sets of contacts and it doesn't matter which one you use.

Depending on the type of connections your garage door opener uses you'll likely want to prepare the other end of the remote wires at this point. Split the conductors back about 3", strip back about 1/2" and tin the wire ends to facilitate connection to your garage door opener terminals.

Use a piece of double-sided foam tape to adhere the relay to the bottom of the box and another piece of foam tape to adhere the box to the z-wave appliance switch.

Step 2: Testing It...

Screw the box lid shut and plug it into the wall.

Before risking frying your garage door opener due to possible wiring or component problems, perform a functional verification (a.k.a. sanity check).

Plug your new creation into the wall and connect a continuity tester across the other end of the remote wires.

Please note that my old DMM (Digital MultiMeter) on it's lowest range shows 320.0 with the "3" blinking to indicate OPEN.

Use the manual switch on the z-wave appliance module to power up your relay. Your continuity tester will show less than 1 ohm and beep (if you have a "tone" mode).

Important:
If you haven't done so yet, be sure to add the z-wave appliance module to your z-wave controller before you install it in your garage! (If you're curious I have a Vera Lite Z-Wave Controller.)

Step 3: Installing It...

Here's my final device plugged in next to my garage door opener.

Important:
Consult your garage door opener's user manual to determine which terminals on the opener are connected to your opener's button on the wall. Connect your switch's wires in parallel to the remote wall button. Be aware that most openers have additional wires for bump and optical safety sensors so don't mix them up.

Now, when your z-wave appliance switch is turned on, your garage door opener will act as if you're holding the wall button. When you turn it off it'll appear as if you've released the wall button. I recommend that you create a scene in your z-wave controller that turns on the switch, pauses for a few seconds, then turns it off. Use the scene to activate the switch.

Additional:
If you install a z-wave door/window sensor then your z-wave system can be set to notify you when the door is left open too long or at certain times, or to trigger the garage door button scene automatically under specified conditions, delays or specific times.

If you use SQ Remote for your iPad you can add Mios sensor controls and scene buttons so you can see the door state and remotely control it from anywhere in the world. Of course your z-wave controller will have a web interface that can do the same thing but I prefer SQ Remote.

I hope you find this informative and useful. Please comment. Whether I left anything out or if you think I've been clear enough, I look forward to reading the reviews from my first Instructable!

Step 4: Create a Scene!

[UPDATE ADDED 01-AUG-2013. Special thanks to Instructables user "Fwaysn" for requesting implementation instructions!]

No, I don't mean you should get all emotional and start throwing stuff around.

To open your garage door you just want to turn on the switch for a few seconds (like pressing the garage door opener button), then turn it off (letting go of the button). Create a new scene where the switch is turned on. Add a delay -- here you can see I set it to 10 seconds. Click that delay and turn off the switch. Each time the scene is executed, the switch will be turned on, pause, then turn off.

I also added a regular Z-Wave door sensor to my garage doors to tell me if they're open or closed. Otherwise you don't know what's happening unless someone tells you or you're there.