What you may be experiencing is an elevator system that is not properly balanced because too much weight was added to the car interior during the renovation.  Not only may this cause poor elevator performance and passenger entrapments, but you may also be in violation of the elevator code. 

The elevator system is designed based on the weight of the cab interior finishes at the time of the original installation.  The elevator code permits cab renovations to exceed this initial weight by no more than 5% of the sum of the rated capacity plus the weight of the car (gross weight).

What happens if I am within the 5% allowable?  

Have your elevator service contractor verify that the elevator system is balanced.  Your contractor may have to provide additional weight to the counterweight system to ensure that the system is properly counterbalanced for accurate control of the elevator.

What happens if I am over the 5% allowable? 

1. Have your elevator service contractor verify that the system components such as machines, hoist ropes, safeties, buffers, guide rails, guide rail brackets and machine beams are designed to withstand the additional weight.

2. Have a structural engineer analyze the building structure to verify that it is designed to withstand the additional weight.  This will include the supports
for the machines, supports at each guide rail bracket location and the loads in the pit.

3. If all of the calculations check out, submit this information to the elevator inspecting authorities for their record and acceptance of the installation.  They may require a new data plate to be installed on the car top crosshead along with the original data plate.

4. If the calculations do not check out, things start to get ugly.  You must remove weight from the elevator system.  This can be accomplished several ways:

   a. Remove or re-design the interior finishes with lightweight materials.
   b. Provide a complete new car shell using aluminum wall panels to
       replace the existing steel or plywood shell.
   c. You may be able to de-rate the elevator rated capacity based on the        interior dimensions of the cab to reduce the “gross weight” of the        system.  The rated capacity of an elevator is based on the inside floor        area of the cab.  Most industry standard cabs have a floor area that is        less than the code allowed rated capacity. Sometimes you can pick-up        100# to 400# by measuring the floor area and checking this with the
       code to determine the corresponding rated capacity.  Your 3500-pound        capacity elevator may have a floor area that is equal to 3100 pounds by        code standards.

What steps should I take when doing an elevator cab renovation?

1. Have your elevator service contractor obtain the car weight and capacity from the car crosshead data plate.

2. Have your elevator service contractor weigh the cab to determine the actual weight.  You may be over the limit already if the cab has been previously renovated or if the estimated cab weight from the original installation was incorrect to begin with.  This will let you know how much weight can be added to the system without having to go through the expense of the structural calculation process.

3. Design the cab interior finishes within the 5% code allowable limit.  Remember, you will be removing the existing interior finishes so you should deduct this weight as well. 

4. Keep in mind that the new interior finishes must comply with the current code regarding flame spread and smoke density characteristics.

5. Have your service contractor adjust the balance of the car and counterweight.

6. Keep a log of the actual weight, what weight was removed and what weight was added.  Post one copy in the machine room and keep one copy with your elevator files.

7. Stay within the 5% limit or prepare to:

    a. Spend some more money
    b. Have the elevators shut down.
    c. Put your tenants at risk.
    d. Put your company or yourself at risk with your tenants.