Guide
How Many Door and Motion Sensors Does a Home Need?
A typical single-family house needs 9 to 11 sensors: one door and window sensor on every exterior door and every ground-floor window that opens, 2 motion sensors covering the main floor and the bedroom hallway, and 1 glass break sensor in the room with the most glass. An apartment needs 3 to 4. This guide gives the counting rule, totals by home size, where motion sensors go, and what the count costs at $50 per sensor.
The Counting Rule
Count 1 sensor per exterior door, 1 per ground-floor window that opens and is reachable, 1 motion sensor per 400 to 600 square feet of open living space plus 1 for the bedroom hallway, and 1 glass break per room with 3 or more windows; skip second-floor windows without a roof below and windows painted shut.
Counts by Home Size
The table applies the rule to 5 home types.
| Home | Exterior doors | Windows to cover | Motion | Glass break | Total | Cost at ${usd(E.sensor)} |
|---|---|---|---|---|---|---|
| Apartment | 1 to 2 | 1 to 2 | 1 | 0 | 3 to 5 | $150 to $250 |
| Townhouse | 2 | 2 to 3 | 1 | 0 to 1 | 5 to 7 | $250 to $350 |
| Single-family, 1,800 sq ft | 3 | 4 to 5 | 2 | 1 | 10 to 11 | $500 to $550 |
| Single-family, 3,000 sq ft | 4 | 6 to 8 | 3 | 1 to 2 | 14 to 17 | $700 to $850 |
| Large home with outbuilding | 5 | 8 to 10 | 4 | 2 | 19 to 21 | $950 to $1,050 |
HomeProtect includes 3 door/window sensors and 1 motion; the quote adds the rest.
Motion Sensor Placement
Put the first motion sensor in a corner of the main living area facing the room's path from the most-used entry, the second in the hallway to the bedrooms, and a third in a finished basement or a detached office; mount at 7 to 8 feet, away from stairs, radiators, and sunny windows, and set pet immunity for the pet's weight.
The Vivint motion sensor page lists the 33, 55, and 80-pound settings.
What the Count Costs
At $50 per sensor, 6 sensors cost $300, 10 cost $500, and 16 cost $800 at retail, or $13.33/mo per month over 60 months for 16; the HomeProtect package covers the first 4 and the quote prices the rest.
Frequently Asked Questions
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