Construction Corner is a Q&A column committed to answering reader-submitted questions regarding construction and development. Inquiries may be sent to [email protected]. 

Q: I am an area manager for five sites in New Mexico.We are having continuing problems with theft at one of our facilities and suspect it to be tenants.We are interested in controlling access to the elevator cars to only those who have units on the upper floors. How exactly does that work?

Brent in Albuquerque,N.M.

A: Elevator control is a great, cost-effective way to keep tenants on only those floors to which they need access. How it usually works is an access keypad is mounted next to the elevator car and requires a tenant to enter a floor-specific code before it allows access to the upper levels. Different systems work in different ways, but the better ones control which floor you can visit, not just the ability to call the elevator.

If you have more than two stories in your building, you want to make sure your elevator company sets it up so anyone can call the elevator, but only those with the correct floor code can travel to the upper floors. You may also want to consider adding individual door alarms to your units so your manager will be immediately notified when a door is opened by an unauthorized tenant.

Q:My brother and I are trying to decide whetherwe should be using an electromagnetic lock or electric strike for our access door. Is there an advantage of one over the other?

Tina in Glendale,Ariz.

A: An electric strike is a solenoid operated mechanism mounted in the door frame. When power is supplied to the keeper of the strike, the door can be opened without retracting the latch-bolt. An electromagnetic lock is comprised of a steel armature plate attached to the door, which is held against a powerful magnet also mounted to the door. Your consideration should be whether you want your door to be fail-secure or fail-safe.

Fail-secure means the door will be locked during a power outage. Failsafe means it will be unlocked during an outage. Most electric strikes come with an option for fail-safe or fail-secure. Electromagnetic locks are only available in fail-safe, so a battery backup or supplemental locking device may be required. An exit switch or bar is usually required with an electromagnetic lock as well.

Tony Gardner is a licensed contractor and installation manager for QuikStor, a provider of self-storage security and software since 1987. For more information, visit www.quikstor.com.