Strut: A solid one piece of molded sheet metal cut to the same length as the width of your garage door. This reinforcement at the top of your door is there to keep the opener arm that attaches to the top panel of the door from bending top panel when opener pulls on panel to open door. Any garage door with an opener that has an arm and pulls door open from the top panel has to have some kind of strut to protect top panel from damage, no matter how wide the door.

Adding Weight to your garage door will affect the door balance

Anytime you attach anything to your garage door it is going to add weight. The most important thing is how much weight are you adding. A strut typically weighs from 3-5 pounds depending on the thickness of the sheet metal used for the strut. And anytime you add weight to a garage door depending on how much weight it will affect the door balance. One strut is not going to be enough weight to change the balance of the door. Now some doors require multiple struts to reinforce door panels. Multiple struts will affect balance of the door and needs to be taken into consideration.

If weight is added to the door you have to compensate by putting more tension on the torsion springs to properly balance the garage door. I have seen countless times someone has added some kind of insulation not made for garage doors and wonder why the opener is having trouble opening the door.