Knowing how to mount a SimpliSafe Entry Sensor correctly is the difference between a system that works reliably and one that keeps showing a door or window as open when it is not. The two pieces need to line up closely enough when the door or window is closed, the mounting surface needs to hold securely, and unusual trim, metal doors, recessed windows, and garage doors can make an otherwise simple installation more difficult.
SimpliSafe Entry Sensor mounted on a door frame.
This guide covers correct placement on doors and windows, adhesive versus screw mounting, uneven door frames, metal doors, garage doors, replacement adhesive, battery replacement, and what to check if your SimpliSafe Entry Sensor does not consistently recognize when a door or window is closed.
If your main problem is uneven trim or an offset door frame, see our separate guide to mounting a SimpliSafe Entry Sensor on a difficult door frame.
Table of Contents
How a SimpliSafe Entry Sensor Works
A SimpliSafe Entry Sensor consists of two pieces: the sensor and a small magnet. One piece mounts to the moving door or window while the other mounts to the surrounding frame.
When the door or window is closed, the magnet sits close enough to the sensor for the system to recognize it as closed. Opening the door or window moves the magnet away from the sensor and causes the system to report the change to the Base Station.
For current SimpliSafe Entry Sensors, the two pieces should be no more than 1.5 inches apart when the door or window is closed.
Which Piece Goes on the Door?
For most installations, mount the larger Entry Sensor on the fixed door or window frame and the smaller magnet on the moving door or window.
This usually creates the cleanest installation because the larger component stays stationary. However, there is no requirement that the sensor always be on the frame.
What matters is that the sensor and magnet remain properly aligned and stay within the required distance when the door or window is closed.
Decorative molding, deep trim, recessed doors, and unusual jambs sometimes make the opposite arrangement easier. If mounting the magnet on the frame and the sensor on the door provides better alignment, that configuration can work as well.
Adhesive vs. Screws
SimpliSafe gives you two basic ways to mount an Entry Sensor: adhesive or screws.
Adhesive mounting is fast, requires no drilling, and works well on many smooth surfaces, including vinyl window frames and smooth painted trim. It is also convenient when you may eventually want to relocate the sensor.
Screw mounting provides a more permanent attachment. It makes sense on wood trim, questionable painted surfaces, areas where temperature changes have weakened adhesive, or anywhere the original adhesive has already failed.
The Entry Sensor slides off its mounting plate, so installing the plate with screws does not make battery replacement difficult.
How to Mount a SimpliSafe Entry Sensor With Adhesive
Adhesive installation only takes a few minutes, but surface preparation and positioning make a major difference.
- Choose the mounting position. Make sure both pieces can sit close together when the door or window is completely closed.
- Clean the mounting surface. Use an alcohol-based cleaning solution and allow the area to dry completely.
- Test the location. Hold both components in place and open and close the door or window several times.
- Remove the adhesive backing. Avoid touching the exposed adhesive more than necessary.
- Position the sensor. Double-check its alignment before pressing it into place.
- Press firmly for about 30 seconds. This helps establish a good adhesive bond.
- Install the magnet. Position it so the gap between the two pieces is no more than 1.5 inches when closed.
- Test the installation. Open and close the door or window and confirm that neither component catches on the trim or contacts the other.
Best Replacement Adhesive for SimpliSafe Entry Sensors
If you remove or reposition a SimpliSafe Entry Sensor, replacing the original adhesive is usually better than trying to reuse it.
Replacement adhesive is useful when moving into a new house, repainting trim, replacing windows, moving sensors to different doors, or correcting an installation that was poorly aligned.
The Security Sensor Spacers SimpliSafe Entry Sensor Adhesive Set is convenient because the adhesive pieces are already cut for Entry Sensors and magnets.
The set includes pre-cut foam adhesive pieces intended for SimpliSafe door, window, entry, and contact sensors. If you are reinstalling several sensors, the pre-cut pieces are easier to work with than cutting small sections from a large roll of double-sided mounting tape.
How to Mount a SimpliSafe Entry Sensor With Screws
For a more permanent installation, use the mounting holes in the Entry Sensor mounting plate.
- Slide the Entry Sensor off its mounting plate.
- Remove the adhesive material from the plate if necessary.
- Hold the mounting plate in the desired location.
- Check the position of the magnet and confirm the two pieces will align when the door or window is closed.
- Secure the plate using the included screws and a Phillips screwdriver.
- Slide the Entry Sensor back onto the mounting plate.
- Mount the magnet and test the door or window several times.
You generally do not need a large drywall anchor for an Entry Sensor because the sensor is very light. The purpose of the screws is simply to keep the mounting plate securely attached through repeated door or window movement.
Mounting a SimpliSafe Entry Sensor on a Metal Door
Metal doors require a little extra planning.
When mounting the Entry Sensor on a metal surface, SimpliSafe recommends placing a thin piece of cardboard between the Entry Sensor and the metal mounting surface.
If the door or door frame itself is magnetic, placing the smaller magnet component on the magnetic surface can also make the installation easier.
Before removing any adhesive backing, hold both parts in position and repeatedly open and close the door. Confirm that the SimpliSafe system reliably changes between open and closed states.
What If the Door Frame Is Uneven?
Uneven trim is one of the most common SimpliSafe Entry Sensor mounting problems.
Older homes frequently have decorative molding, inset doors, deep trim, unusual jambs, or doors that sit well below the surrounding frame. This can leave the sensor and magnet at different heights even though they are physically close together.
A few ways to correct the problem include:
- Reverse the sensor and magnet positions.
- Move both components farther up or down the frame.
- Mount the sensor near the top edge of the door instead of the side.
- Add a small spacer behind one component.
- Use a mounting bracket designed for the installation.
If the sensor and magnet are close enough horizontally but sit at different heights because of raised trim or a recessed door, a spacer can bring one component forward and improve alignment.
The SimpliSafe Entry Sensor Riser/Spacer Set is designed for this type of installation and can be used behind the sensor or magnet when the door frame prevents the two pieces from lining up naturally.
The sensor and magnet do not need to look perfectly symmetrical. They need to remain close enough for reliable detection without interfering with the movement of the door.
For difficult trim, recessed doors, and larger offsets, see our detailed guide to mounting a SimpliSafe Entry Sensor on a door frame.
Mounting a SimpliSafe Entry Sensor on a Window
The same basic mounting rules apply to windows, but window construction varies considerably.
On a conventional double-hung window, you can usually attach the Entry Sensor to the fixed frame and the magnet to the moving sash.
Before installing either piece, confirm that it will not interfere with opening, closing, tilting, locking, or removing the window for cleaning.
Casement windows can require more experimentation because the sash swings outward instead of sliding vertically. Check the entire range of motion before using adhesive.
If you also want protection against broken glass rather than just an opened window, a SimpliSafe Glassbreak Sensor serves a different purpose and is mounted in the room rather than directly on the window.
Entry Sensor vs. Glassbreak Sensor
A SimpliSafe Entry Sensor and a Glassbreak Sensor protect against different types of activity.
An Entry Sensor detects when a door or window opens. Opening the protected door or window separates the magnet from the sensor.
A Glassbreak Sensor listens for the sound of breaking glass. The window does not need to move for a Glassbreak Sensor to detect an event.
In rooms with large or accessible windows, using both types of sensors can make sense because they monitor different conditions.
See our SimpliSafe Glassbreak Sensor mounting and placement guide for installation recommendations.
Mounting a SimpliSafe Entry Sensor on a Garage Door
Garage doors are more difficult than ordinary doors because the mounting surfaces move differently.
A sectional garage door bends and changes angle as each panel moves through the track. A sensor or magnet that looks properly aligned when the door is closed can interfere with another door section, roller, bracket, or track while the door is moving.
A purpose-built garage door bracket can help maintain a usable sensor position while providing enough clearance for the door to travel normally.
The TAKHRWOD Garage Door Bracket Compatible with SimpliSafe Entry Sensors is designed specifically for this type of installation. It includes pre-installed double-sided mounting tape along with mounting holes and screws.
It is most useful when the geometry of a sectional garage door makes it difficult to position the Entry Sensor and magnet directly across from each other using the factory mounting plates alone.
Before making the installation permanent, manually run the garage door through a complete opening and closing cycle.
Watch the sensor, magnet, bracket, rollers, tracks, hinges, and adjoining door sections throughout the entire movement. Nothing should touch the sensor or place pressure on the bracket.
Pairing the Entry Sensor
You can add a new Entry Sensor through the SimpliSafe mobile app.
- Open the SimpliSafe app.
- Open the menu and select the option to add a device or camera.
- Select Entry Sensor.
- Pull the battery tab if you are installing a new sensor.
- Press and release the setup button on the sensor.
- Follow the app prompts to complete setup and name the sensor.
Pair the sensor before making a difficult mounting location permanent. This gives you a chance to verify communication with the Base Station while the sensor is still easy to reposition.
Test the Entry Sensor Before You Finish
Once the SimpliSafe Entry Sensor is installed, open and close the protected door or window several times.
Make sure the system consistently recognizes both states.
If the system occasionally reports that the door or window is open when it is closed, check these items first:
- The distance between the sensor and magnet.
- The alignment of the two components.
- Whether either component moves when the door or window closes.
- Whether the adhesive or mounting plate has started to loosen.
A sensor that recognizes the closed position only some of the time needs to be repositioned. Adjust the sensor or magnet until the system reports the correct state consistently.
What Battery Does a SimpliSafe Entry Sensor Use?
The current SimpliSafe Entry Sensor uses one CR2032 3V lithium coin battery. SimpliSafe lists battery life at up to approximately five years, depending on use and placement.
If you have several Entry Sensors in the house, keeping spare CR2032 batteries available makes sense. The Duracell CR2032 3V Lithium Battery 9-Pack gives you enough replacements for several sensors without buying batteries one at a time.
To replace the battery, slide the Entry Sensor off its mounting bracket toward the pairing button.
Because the sensor separates from the mounting plate, a properly mounted sensor should not require you to remove the adhesive or mounting screws simply to change the battery.
Common SimpliSafe Entry Sensor Mounting Mistakes
Installing the pieces too far apart. The Entry Sensor and magnet should be no more than 1.5 inches apart when the door or window is closed.
Sticking the sensor down before testing the position. Hold both parts in place and operate the door or window before committing to the adhesive.
Ignoring uneven trim. The two pieces do not have to sit on identical surfaces. Reversing the sensor and magnet, moving them, or using a spacer can improve alignment.
Reusing old adhesive. If you remove an Entry Sensor, install fresh adhesive rather than trusting a strip that has already been pulled from a wall, window, or door frame.
Skipping surface preparation. Dust, grease, cleaning residue, and loose paint can weaken the adhesive bond.
Mounting the sensor where it gets bumped. Keep the sensor toward the upper portion of the door or window where furniture, pets, vacuum cleaners, and everyday activity are less likely to hit it.
Failing to test the full range of motion. This is particularly important on casement windows and sectional garage doors.
Frequently Asked Questions
How close do the two SimpliSafe Entry Sensor pieces need to be?
The SimpliSafe Entry Sensor and magnet should be no more than 1.5 inches apart when the door or window is closed.
Can the magnet and sensor be at different heights?
A small offset can still work, but test the proposed installation before attaching either component permanently. If decorative molding creates a large difference in height, reposition the components, reverse their positions, or use a spacer.
Can I use double-sided tape instead of the original adhesive?
Yes. Use appropriately sized mounting tape that holds securely and does not interfere with removing the Entry Sensor from its mounting plate. Pre-cut replacement adhesive made for Entry Sensors is easier to install neatly.
Can I screw a SimpliSafe Entry Sensor into the door frame?
Yes. The Entry Sensor mounting plate can be installed using screws when you want a more permanent attachment.
Can I move a SimpliSafe Entry Sensor to another door?
Yes. Remove the sensor from its mounting bracket, relocate the mounting components, and use fresh adhesive or screws at the new location.
See our guide on how to remove a SimpliSafe Entry Sensor before pulling an adhesive-mounted sensor from painted trim.
Should I put Entry Sensors on every window?
That depends on how you want the security system configured. Entry Sensors monitor whether individual windows open, while other SimpliSafe sensors can provide additional types of coverage.
Other SimpliSafe Mounting Guides
- How to Mount a SimpliSafe Glassbreak Sensor
- SimpliSafe SimpliCam Mounting Options
- How to Mount a SimpliSafe Keypad
- How to Remove a SimpliSafe Entry Sensor
- How to Mount a SimpliSafe Entry Sensor on a Door Frame
Final Thoughts
For a normal door or window, mounting a SimpliSafe Entry Sensor should only take a few minutes. Spending a little extra time choosing and testing the mounting position is more important than installing the adhesive quickly.
Keep the Entry Sensor and magnet within 1.5 inches when the door or window is closed, make sure the two pieces remain aligned during normal operation, thoroughly clean adhesive mounting surfaces, and use fresh adhesive whenever a sensor is relocated.
Uneven trim, metal doors, recessed windows, and sectional garage doors sometimes require a different mounting position, spacer, or bracket, but the same rule applies to every installation: the system should recognize the door or window as open and closed correctly every single time.
