Many existing buildings throughout the United States were built to comply with an earlier building code or with no code, yet are often still safe and sound. Many of these buildings continue to be occupied, used and maintained. However, existing buildings in many urban areas remain vacant, in part because rehabilitation projects trigger requirements to bring existing buildings into compliance with building codes for new construction.

For new buildings, complying with the construction code is a straightforward process. Materials to be used, processes to be followed and safety standards to be met are clearly stated, and the cost of compliance is predictable. Compliance is less straightforward in the case of existing buildings. Construction standards written for new buildings have been applied to rehabilitation work on existing buildings with often prohibitive costs. Building codes developed with new construction in mind are difficult to apply rationally and predictably to existing buildings. If developers and building owners cannot predict with certainty what will be required to bring a deteriorated building back into use, projects in existing buildings will be less attractive.


Prior to the development of the Rehabilitation Subcode,1 the New Jersey regulations triggered code requirements for work in existing buildings based on the cost of the construction project. The greater the ratio of the cost of the project to the replacement value of the building, the more the building needed to comply with the standards for new buildings. Other approaches, such as the method outlined in Chapter 34 of the International Building Code (IBC)2, use new building construction as the benchmark against which existing buildings are measured.


Chapter 34 of the IBC begins with the premise that altered portions of the building must meet requirements for new structures. As an alternative, the code allow the user to go through an extensive evaluation of the building. The building is given points for fire safety systems and features that meet or exceed the code requirements for a new structure. Negative points are assessed for features that are viewed as hazardous; no points are awarded for features deemed to have neither a positive nor negative effect on the fire safety of the building. If the existing building does not meet a specified point value after assessing these features, the building owner is required to provide improvements. This often requires building owners to add features and fire safety systems to the building that would not be required if the building were new.

Basing requirements for existing buildings on the standards for new construction causes several problems:

  1. In many cases, the requirements for new structures cannot be met in existing buildings. Code requirements for new construction contain numerous dimensional requirements that can be difficult, if not impossible, to meet. For example, new building requirements for stairway geometry (minimum tread and maximum riser dimensions) often mean that existing stairways are too steep and need to be replaced. Stairways with shorter risers and longer treads require more room and often cannot fit into existing buildings without totally reconfiguring the space. Other new construction dimensional requirements that cannot be easily met in existing buildings are ceiling height requirements, egress window requirements, corridor and door-way width requirements, and sometimes the most difficult to meet, building height and area requirements.
  2. A second problem is predictability. Code officials generally recognize that making an existing building meet all of the requirements of the code applicable to new buildings is impossible. However, it is equally impossible for the building owner or design professional to predict which requirements of the code the enforcing agencies will deem necessary to improve safety. Quite often, this information is not known until the project has been submitted for permitting. There is an additional level of uncertainty because it is difficult to predict what obstacles will be encountered when trying to place a new building system into an existing structure. This uncertainty makes cost estimations arbitrary, at best. 

  3. Rules that aim to impose new construction standards on existing buildings penalize building owners who want to improve their buildings. Basing code compliance on the ratio of the cost of work to the value of the building places an undue burden on the building owner who chooses a "higher end" product. Furthermore, similar rules can expand the applicant's scope of work by requiring renovation of features that are neither unsafe nor in disrepair. The additional costs associated with expanding the applicant's scope of work can make the rehabilitation project financially infeasible, causing the building owner to abandon planned improvements.

New Jersey's Approach

The challenge accepted by New Jersey was to develop rational and predictable code requirements for existing buildings that delivered safe and sound rehabilitated structures.


Instead of basing requirements on the cost of the work to be performed, the Rehabilitation Subcode bases requirements on the nature of the work. The code establishes specific requirements for each category of work. These requirements are:


Products and practices. Products and practices list the items that are required and those that are prohibited.


Materials and methods. The Materials and methods section identifies the provisions of the codes for new construction that are required for the building components being introduced. This section does not contain any of the scoping requirements of the codes for new construction; it contains the requirements for the materials and the installation methods for building components that are within the owner's intended scope of work. For example, the section of the code for the installation of gypsum wallboard is included in the materials and methods section; however, there are no scoping provisions that require the wall being constructed to be afforded a fire-resistance rating in this section.

New building elements created as part of a rehabilitation project. Each item listed in this section must conform to requirements for new construction as provided in the new building elements section of the Rehab Subcode. Some examples of new building elements are new atriums, new corridors and new door openings.


Basic requirements. Basic requirements cover topics such as capacity of means of egress, deadend corridors and exit signs. They are imposed only within the work area when the work is a reconstruction project. In New Jersey, the "Basic Requirements" are rooted in the New Jersey Fire Safety Code (which is based on the 2006 edition of the International Fire Code3). The New Jersey Fire Safety Code establishes the minimum level of life and fire safety for all existing buildings. The "Basic Requirements" in the Rehabilitation Subcode match the requirements contained in the New Jersey Fire Safety Code. If an existing building that complies with the New Jersey Fire Safety Code not undergoing a construction project is deemed safe, an existing building that is undergoing a construction project is equally safe if it complies with the same requirements.


Supplemental requirements are imposed when the work is a reconstruction project and the work area exceeds a certain size. There are times when the construction project is so large that expanding the scope of the project is reasonable. For example, if a construction project encompasses more than 50 percent of the gross enclosed floor area of a building that must be provided with a fire alarm system, the alarm system is required to be expanded to the entire building. The scope of the intended project is expanded in a rational and predictable manner.


To apply these requirements uniformly, the Rehabilitation Subcode establishes four categories of rehabilitation work: repair, renovation, alteration and reconstruction. The four categories of work are mutually exclusive and are defined as follows:

  1. "Repair" means fixing a building component that is worn or broken. Under this category, materials and assemblies may be replaced with like materials and assemblies. There is no limit to how much repair may be undertaken in connection with a project. There are only a few specific exceptions to this rule. These exceptions include requiring certain products and practices, such as the installation of safety glazing in specific hazardous locations, and prohibiting other items, such as certain electrical materials or supplies.
  2. "Renovation" is restorative in nature, such as the replacement of interior finish, trim, doors or equipment, but involves the use of different materials. There is no reconfiguration of space. As with "Repairs," there are certain products and practices that must be used or are prohibited. Additionally, the materials used and the methods of installation must conform to the requirements found in the materials and methods section. This type of work contains no requirements that will expand the scope of the intended project.
  3. An "alteration" project involves the reconfiguration of an existing space. Products and practices and materials and methods requirements apply to alteration work. New building elements installed as part of the alteration project must comply with the referenced sections of the codes for new construction.

    In an alteration, the portion of the building being altered does not need to be brought up to the standard established in the basic requirements. The basic requirements are used as a measuring stick. The work being done cannot make the building less conforming to the basic requirements than it was before the work was undertaken.
  4. "Reconstruction" is a project that consists of the other categories of work where the work includes an entire tenancy (a portion that is under the ownership or control of one owner or tenant) and precludes occupancy during the project. This category is more of a "quantity" of work rather than a category of work and is commonly referred to as a "gut rehab." Reconstruction includes repair, renovation and/or alteration in any combination.

Repair, renovation and alteration work that make up a reconstruction project must comply with the requirements for the applicable category of work. The entire work area must comply with basic requirements. Certain reconstruction projects also must meet the supplemental requirements, which apply only when the work area for a reconstruction project exceeds a specific size.


Another type of project that can be undertaken as an existing building is a "Change of Use." A "change of use" results from one of two conditions: a change of the building occupancy classification or a change in the nature or intensity of the use. The "Change of Use" section details what must be done, for example, when a building that has been a store (Group M) is changed into a restaurant (Group A) or when a small restaurant is expanded. The change in the use of the building space may initiate requirements of one or more of the codes for new construction. For example, the plumbing subcode may require additional toilet fixtures, the electrical subcode may require ground fault circuit interrupters, or the mechanical subcode may require that the heating, ventilation and air conditioning system be upgraded. The amount of work required depends on whether the occupancy change creates a greater hazard or intensity as defined in the code.


The "Change of Use" section contains six "hazard" tables. These tables establish the concept of an increase in hazard that may be associated with the change in the occupancy classification of the building. The first table categorizes the overall hazard associated with the new use group relative to the existing use group. The next five tables address specific hazards associated with the following technical issues: means of egress, height and area, exposure of exterior walls, fire suppression systems and structural loads. These tables operate independently of one another. Additionally, there are separate requirements for vertical openings, fire alarm, fire detection and smoke detectors. There are also separate sections that address work required by the plumbing, electrical , mechanical or accessibility codes.


The last type of project that can be undertaken on an existing building is an "addition." Simply put, an addition is required to comply with the provisions of the codes for new construction; however, the other sections of the Rehabilitation Subcode apply to the existing portion of the building.


John Terry is with the State of New Jersey.



  1. Rehabilitation Subcode, N.J.A.C. 5:23-6, Department of Community Affairs, Trenton, NJ, 2009.
  2. International Building Code, International Code Council, Washington, DC, 2009.
  3. International Fire Code, International Code Council, Washington, DC, 2006.