How to Position Indoor PIR Sensors for Zero Dead Zones

By Roombanker Engineering Team | Published May 20, 2026

You mount a PIR sensor at 2.2 metres, point it at the centre of the room, run a walk test, and get green lights across the board. Three days later the customer calls: the alarm didn’t trigger when someone walked through the living room. You drive back, climb the ladder, and find the sensor’s field of view was blocked by a tall bookshelf you didn’t account for.

Dead zones are the most common cause of false negatives in passive infrared detection, and they are almost always avoidable. This guide covers how PIR detection patterns work, where to place sensors room by room, and how to verify coverage using the RB Link app before you leave the site.

The recommendations here are based on the Roombanker Indoor PIR Motion Sensor (product page) tested to EN 50131-2-2 Grade 2 specifications, combined with field deployment data from 120+ European installations documented by the Roombanker partner network between 2023 and 2025.

Equipment and Tools You Will Need

This guide references the following Roombanker products and tools. Exact model numbers are listed on each product page:

Product specifications available on each product page. Quantities are typical for a 3-bedroom European residential installation; adjust based on site survey.

How PIR Detection Patterns Work

A passive infrared sensor detects changes in infrared radiation across its field of view. A person moving through the detection area emits body heat that differs from the background temperature of the room. The sensor’s pyroelectric element converts this change into an electrical signal.

What determines where the sensor detects motion is the Fresnel lens array mounted over the sensor element.

Fresnel Lens and Beam Pattern

The Fresnel lens segments the field of view into discrete detection beams. Each beam is a narrow cone of sensitivity. The lens concentrates infrared energy from each beam onto the pyroelectric sensor. A triggering event requires the person to cross from one beam into an adjacent beam — this is what creates the “on-off-on” signal pattern the electronics recognise as motion.

Roombanker Indoor PIR Motion Sensors use a multi-level Fresnel lens with 3 to 5 vertical beam layers (also called “curtains”). Each layer covers a different vertical angle, creating a stacked detection zone. A person walking through the room will cross multiple beam layers, ensuring reliable detection regardless of their height or walking posture.

Vertical Coverage Angles

Vertically, the sensor’s detection beams span approximately 2 to 3 distinct zones:

• Lower zone: Detects motion at ground level to approximately knee height
• Middle zone: Covers torso height — this is where most walk-through motion is detected
• Upper zone: Detects motion at head height and above (relevant for tall individuals or pets on furniture)

The vertical coverage angle is typically 15° to 20° above and below the horizontal centreline. At a mounting height of 2.2 m and a range of 12 m, the lower detection beam reaches the floor at approximately 3 m from the sensor. This creates a blind zone directly beneath the sensor — which is why you never place a sensor expecting it to cover the area immediately below its mounting point.

Horizontal Coverage Angles

Horizontally, the Fresnel lens determines the detection pattern width. Roombanker Indoor PIR Motion Sensors are available in three standard patterns:

Data source: Roombanker engineering specifications (EN 50131-2-2 Grade 2, tested at Roombanker test facility, Shenzhen, 2024). Range values measured in indoor conditions with 20-25°C ambient temperature and 50% relative humidity.

Text Diagram: 110° Wide-Angle Coverage

                   Sensor
                     |
                    /|\
                   / | \
                  /  |  \
                 /   |   \
                /    |    \
               /     |     \
              /      |      \
             /  110°  |       \
            / angle   |        \
           /__________|_________\  Detection boundary (12 m)
          /  Blind    |   Blind  \
         /   zone     |   zone    \
        /    below    |   below    \

The shaded area directly below the sensor (the first 2-3 m of the floor) is the blind zone. No detection occurs here because the lowest beam layer has not yet reached the floor. This is not a defect — it is a property of how Fresnel beam geometry works.

Mounting Height Rules

The mounting height determines where the detection beams intersect the floor and the overall coverage area. Getting this right is the single most important factor in eliminating dead zones.

General rule: Mount at 2.0-2.5 m measured from the floor to the bottom of the sensor. The Roombanker Indoor PIR Motion Sensor includes a tilt bracket that allows 10° downward adjustment, which helps aim the detection zone into the room if the mounting height is at the upper end of the range.

If you must mount above 2.5 m (e.g., on a high ceiling in a commercial space), use the ceiling-mount 360° sensor variant instead.

Data source: Roombanker installation field notes, 30 residential test sites in Germany and Poland, 2024-2025. Coverage distances measured from wall surface to nearest detection beam intersection with finished floor level.

Room-by-Room Placement Guide

Each room type has different furniture layouts, traffic patterns, and environmental factors that affect PIR coverage. The following recommendations are based on typical European residential construction (brick or concrete walls, plasterboard partitions, solid or suspended floors).

Living Room

Place the sensor on a wall perpendicular to the main seating area, at 2.2 m height. Avoid pointing the sensor directly at sofas or armchairs — these absorb body heat and reduce contrast. The ideal position is on a side wall, covering the walking path between the door and the seating area. If the room has a large window, position the sensor so its beams run parallel to the window plane, not directly facing it (see “Facing Windows” below).

Recommended approach: One sensor in the corner, angled 45° into the room, covers most living rooms up to 40 m². For larger spaces, add a second sensor on the opposite wall.

Bedroom

Mount the sensor on a wall that does not face the bed directly. A sensor aimed at a bed will have reduced sensitivity because the sleeping occupant (or the bed itself soaked with body heat) creates a warm background that reduces thermal contrast with an intruder. Place the sensor on the wall beside the bed, covering the doorway and the walking path. Alternatively, mount in a corner covering the door and window.

Hallway

Hallways are the strongest application for long-range (90° curtain) PIR sensors. Mount at one end of the hallway, directed along the length. The curtain pattern creates a narrow detection fence that a person must cross — ideal for long, straight corridors. For L-shaped hallways, use two sensors: one for each segment, mounted at the corner to provide overlapping coverage.

Concrete wall consideration: European hallways often have load-bearing concrete walls on one or both sides. Mount the sensor on the concrete side — the thermal mass of concrete provides a stable background temperature, improving detection reliability compared to a lightweight partition wall that heats and cools rapidly.

Kitchen

Kitchens present unique challenges because of heat sources. The refrigerator compressor cycle, oven ambient heat, and sunlight from kitchen windows all produce temperature fluctuations that can either mask an intruder or cause false triggers.

Mount the sensor at least 2 m away from the refrigerator and 3 m from the oven or hob area. Position it to cover the kitchen entrance and the main walking path. Do not aim at the refrigerator — warm air from the rear condenser coil creates a temperature gradient that degrades PIR performance.

Staircase

Mount the sensor at the top of the stairs, angled downward along the staircase. Use the tilt bracket to direct the lower beam zone onto the stair treads. A single sensor at the top covers both the staircase and the landing area. For split-level or winding staircases, place a sensor at each landing.

Garage

Garages have large temperature swings and often lack insulation. Mount the sensor on a wall away from the garage door. If the garage door is metal, the sensor should not be mounted on the same wall — temperature conduction through metal panels creates false triggers. Keep the sensor at least 1 m from any vehicle parking area to avoid the engine block’s residual heat.

Basement

Basements in European buildings typically have concrete walls and often contain HVAC equipment, boilers, or water heaters. Mount the sensor at least 3 m from any heat-producing equipment. Position it to cover the staircase entrance and the main floor area. For finished basements with furniture and partition walls, treat the layout like a living room and use multiple sensors for irregular floor plans.

Dead Zone Avoidance

Even with correct mounting height and angle, dead zones can form when the detection beams are physically blocked or redirected. Here are the most common culprits and how to handle them.

Behind Furniture

Tall furniture — wardrobes, bookshelves, cabinets — creates solid shadow zones. A PIR detection beam cannot pass through wood or particle board. If a wardrobe is against the wall where you want to mount the sensor, move the sensor to an adjacent wall so its beams travel across the room rather than through the furniture.

Rule of thumb: Any object taller than 1.2 m within the detection zone will create a shadow. Map furniture heights during the site survey and position the sensor to work around them.

Near HVAC Vents

Heating and air conditioning vents produce moving air at a temperature different from the room ambient. This creates a fluctuating infrared background that can either mask an intruder signal or cause false triggers. Keep sensors at least 1.5 m from any HVAC supply or return vent. In rooms with underfloor heating (common in European bathrooms and kitchens), mount the sensor toward the upper end of the height range (2.5 m) and angle it slightly downward to keep the beams above the warm floor layer.

Facing Windows

Sunlight streaming through a window heats the floor and wall surfaces in a moving pattern throughout the day. A PIR sensor facing a window will detect these changing thermal gradients as motion, causing false alarms particularly in the early morning and late afternoon.

Mount the sensor on a wall adjacent to the window, not opposite it. If the room layout requires the sensor to face a window, position it at least 3 m from the window and ensure curtains or blinds are closed during the armed period.

Corner Placement

Corners are generally the best mounting position for PIR sensors, but with one caveat: the corner must have a clear field of view across the entire room. A corner adjacent to a doorway means the sensor will only detect movement once the person has entered the room — the doorway itself is a dead zone. For corner-mounted sensors, the ideal corner is the one farthest from the main entry point.

Common Placement Mistakes

1. Aiming directly at heat sources. Radiators, boilers, ovens, and direct sunlight all produce infrared radiation that can exceed the sensor’s dynamic range. Keep the sensor’s primary detection axis at least 45° away from any heat source.
2. Mounting too close to the ceiling. Mounting above 2.5 m increases the blind zone to 4-5 m from the wall. A person hugging the wall can walk along it undetected. Always measure the mounting height; don’t guess.
3. Creating coverage gaps between sensors. When using multiple sensors, the gap between their detection patterns must be covered by at least 30% overlap. A gap of more than 2 m between adjacent detection zones is an exploitable dead zone.
4. Placing sensors where the intruder walks toward the sensor. PIR sensors detect motion best when the person walks across the detection beams (perpendicular to the sensor axis). Walking directly toward the sensor produces a smaller infrared signal because fewer beam layers are crossed. Position the sensor to create cross-traffic patterns.
5. Ignoring the pet height during mounting. Mounting at 2.0 m instead of 2.2 m may reduce the pet exclusion zone by 40% (see pet section below).

Data source: Compiled from 120+ European site surveys by Roombanker’s technical support team, 2023-2025. The five most common errors identified were consistent across Germany, Poland, France, and the UK markets.

Multi-Sensor Coverage: Calculating Overlap

For rooms larger than 40 m², rooms with irregular layouts, or rooms divided by partition walls, a single PIR sensor is not sufficient. Multiple sensors must be positioned so their detection zones overlap, leaving no gaps.

Overlap calculation for 110° wide-angle sensors:

• At 12 m range, the detection width at the outer edge is approximately 19 m
• Two sensors on opposite walls will overlap in the centre
• For complete coverage, the distance between two sensors should not exceed 9 m
• This provides approximately 30% overlap at the centre of the room

Overlap calculation for 360° ceiling-mount sensors:

• At 8 m radius, each sensor covers a 16 m diameter circle
• For complete coverage with overlap, space sensors at 11 m centre-to-centre
• This provides approximately 3 m of overlap between adjacent coverage circles

In rooms with concrete columns or structural walls, place sensors on each side of the obstruction. A concrete column 400 mm wide will block detection beams completely. Never assume the beam wraps around an obstacle — it doesn’t.

Pet Considerations

Pet immunity in PIR sensors works by two mechanisms: reducing sensitivity below a threshold weight and masking the lower detection zone. The Roombanker Indoor PIR Motion Sensor offers adjustable pet immunity up to 25 kg.

Mounting Height for Pet Households

Mount the sensor at 2.2 m minimum. At this height, the lowest detection beam reaches the floor at approximately 3 m from the wall. A dog or cat below 25 kg moving within the first 3 m of the sensor will be below all detection beams and will not trigger an alarm.

For households with cats that jump onto furniture near the sensor, or with large dogs (20-25 kg) that move actively through the room, use the lens mask included with the Roombanker Indoor PIR Motion Sensor. The mask blocks the lowest 1-2 beam layers, raising the detection threshold. This reduces the effective coverage range by approximately 2 m but improves pet immunity significantly.

Pet Immunity Test Protocol

After installation in a pet-occupied home, run a 15-minute walk test with the pet present. Have the homeowner walk the pet through each zone at different times of day. If the sensor triggers, install the lens mask and re-test. Document the mask position in the installation notes for future troubleshooting.

European Building Context

European buildings present specific challenges that are less common in other markets.

Concrete Walls and RF Signal Attenuation

Reinforced concrete walls attenuate the RBF wireless signal by 20-30 dB compared to plasterboard. When placing a PIR sensor on a concrete wall, the sensor’s communication link to the Roombanker Hub must be verified using the RSSI check in the RB Link app (see next section). If the RSSI reading is below -85 dBm, consider using a sensor closer to the hub or adding an RBF repeater.

Data source: Roombanker field testing across 30 residential sites in Germany and Poland, 2024-2025. Concrete wall attenuation measured with RBF protocol at 868 MHz (EU frequency band).

Underfloor Heating Interference

Underfloor heating systems (electric or hydronic) create a warm floor surface at 22-28°C. The temperature differential between the floor and a walking person is reduced, which can lower detection sensitivity. In rooms with underfloor heating:

• Mount the sensor at 2.5 m (the upper end of the range)
• Angle the sensor downward to aim the middle beam zone at the walking area
• Use the long-range (90°) pattern if available to concentrate detection energy along the primary walking path
• Test with floor heating ON at full operating temperature, not during the heating-off season

European Wiring and Conduit

Many European properties use surface-mounted conduit for electrical wiring. Do not mount PIR sensors over electrical conduit — the conduit creates a raised surface that may tilt the sensor and shift the detection pattern. Use spacer washers or a mounting plate to create a level mounting surface.

RSSI Verification Using RB Link App

After physically mounting the sensor, verify two things before leaving the site: detection coverage and radio signal strength. The RB Link app (available for iOS and Android) provides both.

Walk Test Procedure

1. Open the RB Link app and navigate to the sensor settings page
2. Enable Walk Test mode — this puts the sensor into a continuous detection state
3. Walk across the room at normal pace, covering every area of the floor plan
4. Each detection event is logged in the app with a timestamp
5. Areas where no detection occurs are dead zones — mark them and adjust the sensor

RSSI Check

1. In the sensor settings page, view the Signal Strength indicator
2. RSSI should be -75 dBm or stronger for reliable communication
3. If RSSI is between -75 dBm and -85 dBm, the signal is marginal — test with the hub in its final position
4. If RSSI is below -85 dBm, relocate the sensor or add an RBF repeater

Important: RSSI is affected by concrete walls, metal-framed windows, and large appliances. Test RSSI with all building systems running (HVAC, appliances) to get a real-world reading.

What a Properly Installed System Looks Like

When PIR sensors are positioned correctly using the guidelines above, the customer experiences:

• Zero false alarms from environmental causes. No triggers from HVAC cycles, sunlight shifts, or radiator heat. The sensor sees only what it should: human motion.
• No undetected entries. Any person entering the protected space crosses at least one detection beam layer before reaching a high-value area. Walk-through paths cover every accessible route.
• Reliable daily operation. The RB Link app shows consistent RSSI values (above -75 dBm) and no missed event logs. Battery life runs to the rated specification because the sensor is not being falsely triggered by environmental noise.
• Pet coexistence. Pets move freely below the detection threshold. The homeowner is not desensitised to alarms by pet triggers.
• Clean site handover. Walk test logs are documented in the RB Link app. The installer leaves with a verified coverage map, not a “should be fine.”

This is the standard the Roombanker partner network aims for across all 120+ European installations documented since 2023.

Frequently Asked Questions

How far can a PIR sensor detect motion?

The Roombanker Indoor PIR Motion Sensor has a rated detection range of 12 m for the wide-angle (110°) pattern and 25 m for the long-range (90°) curtain pattern. These values are measured under standard conditions (EN 50131-2-2 Grade 2, 20-25°C, 50% relative humidity). Actual range may vary based on room temperature, furniture layout, and mounting height.

Can I mount a PIR sensor outdoors under a covered patio?

No. Indoor PIR sensors are not weather-sealed and are not designed for outdoor use even under cover. Temperature fluctuations, humidity, and insects will cause false alarms. Use the Roombanker Outdoor PIR Motion Sensor (product page) for any semi-outdoor or outdoor installation.

What is the minimum distance between two PIR sensors to avoid interference?

PIR sensors are passive — they do not transmit any signal, so they cannot interfere with each other optically. However, two sensors covering the same area will both trigger on the same motion event, sending duplicate transmissions to the hub. This is not harmful but adds radio traffic. For most installations, 3 m minimum separation is sufficient to avoid double-triggering while maintaining overlapping coverage.

Does a PIR sensor work through glass?

No. Glass blocks the infrared wavelengths that PIR sensors detect (8-14 micrometres). A PIR sensor mounted behind a window will not detect motion on the other side of the glass. Always mount the sensor inside the protected space.

How do I test pet immunity before the customer moves in?

Run a walk test with a thermal target at the pet height. A simple method: wear socks, kneel, and crawl through each detection zone at the height of the largest pet expected in the home. If the sensor triggers, install the lens mask and repeat the test. Document the test results in the installation report.

Should I use wide-angle or curtain sensors for a long hallway?

Use curtain (long-range 90°) sensors for hallways. The curtain pattern creates a narrow detection fence across the width of the corridor. A person walking along the hallway must cross this fence, ensuring reliable detection. Wide-angle sensors in hallways produce unnecessary coverage of the walls and may trigger on wall-mounted radiators or windows.

My customer has underfloor heating. Will the PIR sensor work correctly?

Yes, but with adjustments. Mount at 2.5 m height, angle the sensor downward, and run the walk test with the underfloor heating at full operating temperature. The warm floor reduces thermal contrast, so the sensor may need more sensitive placement than a standard room. See the “Underfloor Heating Interference” section above for full guidance.

Download the PIR Placement Checklist

We have compiled a one-page PDF checklist covering every step in this guide: mounting height by room type, dead zone inspection points, overlap calculation table, and a walk test log. Take it on site for quick reference.

Download PIR Placement Checklist PDF — no registration required.

Book a Demo Installation

Want to see these placement principles applied in a real building? Roombanker offers on-site demo installations for security integrators and distributors. Our technical team will walk through a live installation with you, explain each placement decision, and share the walk test results in the RB Link app.

Book a Demo Installation — available in Germany, Poland, France, and the UK.

Further Reading

• How to Conduct a Site Survey for Wireless Security Systems — RF signal mapping and obstacle assessment before installation
• PIR Motion Sensor Troubleshooting: False Alarms and No Detection — Diagnose detection issues after installation
• Dual-Tech vs PIR Sensors: When to Use Each — Comparing PIR-only against dual-technology detectors for high-risk environments

This guide was prepared by the Roombanker Engineering Team based on EN 50131-2-2 Grade 2 testing at the Roombanker test facility (Shenzhen, 2024) and field deployment data from 120+ European installations documented by the Roombanker partner network across Germany, Poland, France, and the UK (2023-2025). Product specifications may vary by region. Always refer to the product manual for installation instructions specific to your sensor model.

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