How to Build a Smart Home Security System Without Monthly Fees

A Ring Protect subscription runs $25 per month. That is $300 per year to store video clips in someone else's cloud and get notifications that a tree branch triggered your camera. A local system does more, stores everything on your own hardware, and costs exactly zero dollars per month after the initial investment.

This guide walks you through every component of a DIY security system built on Home Assistant. No subscriptions, no cloud dependency, and you own all your data.

System Overview: What You Need

A complete DIY security system has five layers:

1. Perimeter detection: Door and window sensors that know when entry points open.
2. Interior detection: Motion sensors and presence detection inside the home.
3. Visual verification: Cameras with local recording and AI object detection.
4. Deterrents: Sirens, lights, and notifications that respond to intrusions.
5. Control panel: Home Assistant acting as the alarm hub with arm/disarm modes.

Layer 1: Door and Window Sensors

Zigbee contact sensors are the backbone of any security system. They tell you instantly when a door or window opens. The Aqara MCCGQ11LM is the go-to recommendation: small, cheap ($10), reliable, and the battery lasts 2+ years.

Place sensors on every exterior door and every ground-floor window that opens. Upper-floor windows are lower priority unless they are accessible from a roof or balcony. Label each sensor clearly in Home Assistant so notifications tell you exactly which entry point opened.

For a typical 3-bedroom house, budget 6-10 contact sensors: front door, back door, garage entry door, and 4-7 windows. That is roughly $60-100 in sensors.

Layer 2: Interior Motion Detection

Motion sensors inside the home provide a second layer of detection in case someone bypasses or breaks through an entry point without triggering a contact sensor. Place PIR motion sensors in hallways and transition areas, these are the paths an intruder must cross to reach valuable areas.

For security purposes, PIR motion sensors are actually better than mmWave here. You want to detect a person walking through a space, which PIR handles well. mmWave sensors are better for occupancy detection (keeping lights on) but can generate more false positives from pets and environmental changes. See our motion sensor placement guide for optimal positioning.

Layer 3: Cameras and Local Recording

This is where DIY systems truly outshine subscription services. Instead of paying monthly for cloud storage, you record everything locally using Frigate NVR running on your Home Assistant server.

Camera Selection

Use cameras that support RTSP (Real-Time Streaming Protocol) for local streaming. Reolink, Amcrest, and Hikvision all support RTSP. Avoid cameras that only work with cloud services (Nest, Ring), they cannot stream to local NVR software. Our camera comparison covers this in detail.

For a typical home, start with:

• 1-2 outdoor cameras covering the front door and driveway.
• 1 outdoor camera covering the back yard or rear entrance.
• 1-2 indoor cameras for main hallways or common areas (optional, some people skip these for privacy).

Budget: $40-80 per camera for Reolink PoE models, so $200-400 for a complete camera setup.

Frigate NVR: AI-Powered Local Detection

Frigate is a free, open-source NVR that runs on your Home Assistant server. What makes it special is real-time AI object detection. Instead of recording every motion event (including cars, shadows, and animals), Frigate identifies what triggered the motion, person, car, dog, cat, and only creates events for categories you care about.

This means you get notifications that say "Person detected at front door" instead of "Motion detected" followed by a clip of a shadow moving. The accuracy is remarkable. With a Google Coral USB accelerator ($30, but hard to find, a CPU-only setup works too), Frigate processes detection at 20+ FPS with almost zero CPU load.

Frigate stores recordings locally on your server's hard drive. A 1TB drive stores roughly 30 days of continuous recording from 4 cameras at standard quality. If you only record when events are detected, that same drive stores months of footage.

Layer 4: Deterrents and Notifications

Siren

A Zigbee siren (like the Heiman HS2WD-E, about $25) produces a 95dB alarm that is loud enough to wake the neighborhood. Trigger it when the alarm is tripped and no valid disarm code is entered within 30 seconds.

Smart Lights

Flash all interior and exterior lights to full brightness when an alarm triggers. This disorients intruders and signals to neighbors that something is wrong. If you have outdoor smart lighting, flash those too.

Notifications

Send push notifications with camera snapshots to your phone via the Home Assistant Companion app. Include the camera snapshot in the notification so you can see what triggered the alarm without opening the app. Also consider sending alerts to a family Telegram or Signal group so multiple people are notified simultaneously.

Layer 5: Home Assistant Alarm Control Panel

Home Assistant has a built-in alarm control panel component that provides arm/disarm functionality with multiple modes:

• Armed Away: All sensors active. Any door, window, or motion triggers the alarm after a 30-second entry delay.
• Armed Home (Night): Door and window sensors active, interior motion sensors disabled. For when you are home and sleeping.
• Disarmed: Sensors still report but no alarm is triggered.

You can arm and disarm through the HA dashboard, a keypad (IKEA SYMFONISK remotes repurposed with Zigbee2MQTT), NFC tags at entry points, or automatically via geofencing when you leave/arrive home. Our geofencing guide covers auto-arm/disarm setups.

Complete System Cost Breakdown

Compare that to Ring Alarm Pro ($300 hardware) plus Ring Protect Plus ($200/year) = $700 in the first year, $900 by year two. The DIY system pays for itself in under 18 months and costs nothing ongoing.