What is an overhead garage door?
There are many different types of garage doors. There are sectional, roll up (commercial use usually), doors that slide to the side, tilt up, and side hinged. The most common garage door installed for use in residential homes is the sectional door that retracts from overhead, or commonly referred to as the overhead garage door, or even more commonly referred to as the garage door.
Types of safety components
A sectional overhead door is one that consists of horizontal panels that are connected by hinges, re-enforced by braces, high tension springs, has rollers installed, with two tracks mounted on the walls and ceilings, and a motor with a belt, chain or screw drive that lifts and lowers the door. In this installation, there are two required safety components that are used to prevent accidental contact with occupants, equipment, or vehicles. The two safety components are the photo eye sensors and the pressure or auto-reverse system. The safety requirements were added to garage doors because if they did not exist, there is enough force to kill a person should they become trapped underneath a closing garage door.
Photo eye sensors
The photo eye sensors are two rectangular boxes that are mounted on the wall or tracks approximately six inches from the ground, on opposing sides of the garage door. They act as transmitters that emit light and receive it. If the light is interrupted, the system stops the closing process and returns the door to the overhead or open position. Interruptions of the light can include a person or object crossing the path of the transmitters while the door is closing. Additionally, the door will not start to close if the transmitters are blocked prior to attempting to close the door. For example, if a bike or car is blocking the transmitters, the door will not close. This safety function has been required on all automatic garage doors, both residential and commercial, since 1993.
There are some errors that are commonly associated with photo eye sensors that do not allow them to operate as intended. The most common error that occurs is that the eyes are out of alignment. This typically occurs when something bumps one of the sensors so that they do not point directly at each other. This will put the garage door system into a state of confusion, thinking that there is an obstruction and will not allow the door to close.
Another error that can occur, is if one or both of the sensors are installed in direct sunlight. This can cause the sensors to not work properly and not allow the door to close as intended.
As home inspectors, we commonly find the sensors installed too high or too low (6” off of the floor). There are occasions that the photo eye sensors are found to be improperly installed. For example, they have been found mounted to the top of the garage door. This type of installation would eliminate the ability to trip the sensors and therefore negate the safety protection. Additionally, there have been times we have discovered that the photo eyes have not been installed at all.
Pressure or auto-reverse system
The auto-reverse system is a secondary form of safety function found on garage doors. This system enacts in the event that, as the garage door is closing, it detects that the garage door has come into contact with an object. This prevents accidental closure on an object or person even if the photo eye sensors have not been triggered. The sensors should be set sensitively enough to detect small amounts of pressure. Similar to the photo eye sensors, the auto-reverse system was also made a requirement in 1993.
How do home inspectors test the safety functions?
Prior to performing any safety function test on the garage door, as home inspectors, we thoroughly inspect the garage door for any loose hardware, dents, damage, split, or any other potential issue that may occur from normal use. If there are any signs of compromised conditions, we will not proceed with the safety function test. As identified, it is important to have safety functions present and operational, but the tests inherently force the door to stop forward movement. Any forward movement, with an abnormality in the door, can cause further damage to the door. In this instance, the door should first be repaired, then have the safety functions tested.
To perform a test on the photo eye sensors, home inspectors initiate the closing of the garage door and walk in the path of the sensor. A properly functioning system then stops the garage door and initiates reversal.
To perform the pressure reverse safety test, home inspectors should initiate the closing of the garage door with a 1.5-inch solid object (or 2x4) placed on the ground at the center of the door. As the door approaches the complete travel, it should press on the object and reverse direction. However, if the system is not functioning correctly or pre-dates the requirement of this feature, with this testing method, there is a high probability of damaging the door. In order to avoid unintended damage, at Dwellinspect Arizona, we do not perform this safety test. Though homeowners should be doing this test every 30 days, this rarely happens. Most garage doors have other issues that the home inspector will find to warrant another inspection and repairs by a garage door professional before the pressure reverse can be tested.
When should safety functions be tested?
According to the operations manual of Liftmaster, they should be tested monthly. If there is any failure, it should be adjusted and repaired as needed.