• Why We have A Rehabilitation Subcode

    In 1996, local construction offices in New Jersey issued building permits authorizing work that had an estimated cost of over $7 billion. Additions and alterations of existing structures accounted for about 47% of this amount. This is a much higher percentage than in most other states. Rehabilitation work is most pronounced in New Jersey's cities where conversions and rehabilitation projects have an integral role in the creation of decent, affordable housing. In Newark, for example, about $3 out of every $4 included in the estimated cost of construction authorized by permit in 1996 was for work on existing houses. In Trenton, housing rehabilitation work outpaced new housing construction by more than 14 to one. 

    New Jersey has an old housing stock, which means that rehabilitation and conversions play a critical role in state, local, for-profit, and nonprofit efforts to expand the supply of affordable housing. Half of the state's 3.1 million houses were built before 1959.  In Hudson and Essex, the counties with the state"s two largest cities, the median year for houses is 1941 and 1949, respectively.  New Jersey also has many older nonresidential buildings that are vacant or under-utilized and are good candidates for adaptive re-use.

    Existing buildings that were built to comply with an earlier building code or with no code are often still safe and sound. Most existing buildings throughout the United States, including those in New Jersey, are in this category. With a few exceptions, these buildings continue to be occupied, used, and maintained. New Jersey has strong retrofit codes that apply to all existing buildings and ensure their safety. It is no longer logical that a building which can remain unimproved must be upgraded in numerous respects, many of which provide very little safety improvement, simply because the owner elects to improve the building. This approach often deters any improvement.

    Both in New Jersey and nationally, the building code, which is oriented towards new construction, can add unnecessarily to the time and expense of rehabilitating existing buildings because it was not written with existing buildings in mind. For new buildings, complying with the construction code is a straightforward process, but it is difficult to apply the code rationally and predictably to existing buildings. Because developers and building owners cannot predict with certainty what will be required to bring a deteriorated building back into use, projects that pose the greatest uncertainty in terms of time and resources are not attempted at all and the buildings remain unused.

    Thus, the challenge facing New Jersey was to develop provisions for existing buildings that were rational, predictable, and that delivered safe and sound rehabilitated structures.

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  • What about the standards in New Jersey for alteration or rehabilitation work in existing buildings--the 25/50% rule?

    Prior to the adoption of the Rehabilitation Subcode, the process in the Uniform Construction Code for dealing with rehabilitation in New Jersey was the 25/50% rule. The 25 and 50 percentages refer to cost - the cost of the alterations in relation to the value of the building.

    There were three ratios or thresholds in the 25/50 percent rule which are relevant: (1) under 25%, (2) 25–50% and (3) over 50% of the building's value. These were applied as follows:

    1. Where the cost of the work was under 25 percent of the value of the structure, the code provided that the subcode official determine the degree to which the alteration work should meet the code requirements for new construction. This gave the subcode official a great deal of discretion and the building owner very little predictability.

    2. Where the cost of the work was between 25 and 50 percent of the structure's value, the code required that the altered or repaired portions meet the requirements for new structures. The configuration of the existing building generally made this difficult to achieve, so that a project often involved one or more variation requests and, again, very little predictability.

    3. When the cost of the work exceeded 50 percent of the structure's value, the code mandated that the requirements for new structures be applied to the entire building, including portions not planned for alteration or repair. This meant that not only rehabilitated areas, but the entire upgraded to the standards for new construction. Again, variation requests were common in this kind of project because of the limitations of the existing building.

    There were three other kinds of percentage rules that impacted construction projects: additions, accessibility, and change of use. When additions exceeded 5% of the area of the existing structure, the existing structure was required to comply with the code for the following items: light, ventilation, means of egress, and fire safety. The 25/50 percent rule affected accessibility by ensuring compliance with all UCC subcodes for a building where the replacement value of the structure was 50% or greater. In a change of use, the building was required to comply with the requirements of the code for the proposed new use group.
    Where did the 25/50% rule come from? Research from the National Conference of States on Building Codes and Standards indicates that the 25/50% rule first appeared in building codes as provisions to address nonconforming buildings within fire districts. As population and building density increased in urban areas, several fire disasters alerted communities that fire could consume entire areas of a city where buildings were of wood frame construction. Thus, the demolition or replacement of wood frame exterior walls with conforming construction was required when the value of work to be undertaken exceeded 50% of the building's value. The original purpose of the rule, therefore, was to prevent, rather than promote, the rehabilitation of certain classes of buildings. It made some sense 75 years ago when large numbers of existing buildings met no building code standards at all, but those buildings are long gone.

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  • The Development of The Rehabilitation Subcode

    The Rehabilitation Subcode was developed by the Department of Community Affairs with guidance from a 30-member committee under the coordination of the Center for Urban Policy Research at Rutgers University. The Committee was composed of code officials, fire officials, architects, historic preservationists, advocates for people with disabilities, and government representatives.  

    The Committee met over two years and approved the draft document at its final meeting on January 31, 1997. Department staff then made the draft a proposal, which was published in the New Jersey Register on August 18, 1997.  

    Two public hearing were held. Comments were received and discussed and some clarifications and improvements to the proposed document were made. The adoption of the Rehabilitation Subcode was published in the New Jersey Register on January 5, 1998.  

    The Rehabilitation Subcode is the first comprehensive set of code requirements for existing buildings. It is a stand-alone subchapter and, therefore, it contains all the technical requirements that apply to a rehabilitation project. This is an important concept.  

    The Rehabilitation Subcode is a technical part of the Uniform Construction Code and, therefore, has no provisions governing permits. This does not mean that permits are not required. In fact, the provisions for permits and other administrative procedures are where they have always been, in Subchapter 2 of the Uniform Construction Code, and work that required a permit before the adoption of the Rehab Subcode, requires a permit now. This is discussed in more detail in the section on Administrative Requirements.

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  • Parts of The Rehabilitation Subcode

    The Rehab Subcode is divided into parts that are quite different from the new construction subcodes and must be understood if the Rehabilitation Subcode is to be understood.  

    There are three types of projects: Rehabilitation; Change of Use; and Additions.  

    There are four Categories of Rehabilitation: repair, renovation, alteration, and reconstruction. They relate to the extent of the work undertaken.  

    There are five Sets of Requirements: products and practices; materials and methods; new building elements; basic requirements; and supplemental requirements that apply to the categories of work. The best way to see how the categories and sets of requirements work together is to review the matrix.  

    The Rehab Subcode also includes an Introduction. Because the rehab subcode is a new approach to establishing requirements for work in existing buildings and because it is expected that this subcode will be used both by those who are familiar with the current Uniform Construction Code (UCC) and those who are not, it was decided that this rule should include a less formal, introductory section than is usually included in regulations.  

    The introduction sets the stage for the requirements that follow. It is designed as a user friendly summary of the Rehab Subcode. It is critical to understand that this introduction is not in strict code language and cannot be cited as a code requirement. The concepts contained in the introduction are included in the remainder of the Rehab Subcode.

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  • Terms and Concepts

    Terms and Concepts

    The following terms and concepts are used in the Rehab Subcode in a new way and are central to understanding the Rehab Subcode as a whole. 

    Work Area

    The work area is defined in the regulations as "any entire use, primary function space, or tenancy comprising all or part of a reconstruction project as delineated on the approved permit application and for plans."  

    Work area means what it says literally—it is where the work is being done. The only time the concept of work area is applied is in a reconstruction project. 

    De minimis

    This concept is used only in connection with supplemental requirements. It may cause concern because it does not specify a black and white "hard" number. The supplemental requirements are applicable when the work area is an entire floor or a specified percentage of the entire building. In order to prevent arguments based on what proportion of a floor or building could remain "untouched" in order to circumvent the supplemental requirements, the concept of de minimis, or insignificant, amount of excluded area was incorporated into this subcode. Admittedly, this requires judgment by the code official. It is a move toward invoking common sense and is a move away from invoking the "letter of the law" without also applying common sense.  

    For instance, rather than use numbers such as 100% of a floor or 90% of a floor, the rehab code uses words such as "entire" floor. If an applicant indicates he or she is doing a reconstruction on everything on the floor except a closet, that still is equivalent to the entire floor. Leaving out a small part or an insignificant portion of the floor is de minimis and, therefore, does not change the designation of the work area involving the whole floor. The reason the words de minimis were chosen instead of a number, such as 95%, was to eliminate discussions about how to get to a percentage of what was measured. If, in the example above, the closet resulted in a number of 94.1% of the floor area rather than 95%, there could be a discussion, maybe even an argument, about whether the provisions triggered by 95% should be applied. Because there may be a desire to circumvent the supplemental requirements, the term de minimis was included to control the tendency to "cheat" or to try to imply loopholes where none were intended. De minimis means use common sense. 


    A tenancy is an entire building, or a portion of a building, or a story, or a portion of a story that is under the ownership or control of one owner or tenant. This term is used in determining whether a project is a reconstruction project, which involves an entire building or tenancy. Within the context of dwelling units, tenancy means the entire dwelling unit. 

    Primary Function Space

    The primary function space is the use for which a building, or portion of a multi-use building, is intended. The easiest way to define primary function space is by use group. Just as there can be more than one use group designation within a building, so can there be more than one primary function space. The term is applied to accessibility requirements and is also used in the definition of work area. Where a reconstruction is performed on primary function space, an accessible path of travel to the reconstructed space must be provided, except that the cost of providing the path of travel must be proportionate to the cost of the project. A cost is disproportionate when it exceeds 20% of the cost of the project. A project may be a reconstruction project if it includes all of a primary function space and meets the other provisions of the definition of reconstruction. 

    Path of Travel

    The term path of travel refers to the route that is taken to reach a primary function space. There are six elements of a path of travel: parking, building entrance, interior route, bathrooms, drinking fountains, and telephones. When work is undertaken in a primary function space, the accessibility of the path of travel to the primary function space must be improved. The improvement must be made to one or more of the six elements of the path of travel given above, but the cost of the improvement is not required to be disproportionate to the overall cost of the planned alteration project. A cost is considered disproportionate if it exceeds 20% of the project. 

    Technically Infeasible

    The term technically infeasible applies only to accessibility requirements. It means that when reconfiguring space in an existing building, if it is not possible to meet the full or exact dimension required by the accessibility standard, the space should comply to as great an extent as is possible. Meeting an accessibility standard measurement may be impossible because of structural problems or it may not be possible without expanding the planned scope of work. Whichever the reason, the differing dimension should be recorded by issuing a variation. The easiest way to think of this provision is to "do what you can" given the building and the scope of work. 

    Hazard Index

    The hazard index is used throughout the change of use requirements to determine whether a change from one specific use group to another increases the life safety hazard of the building. The hazard index is applied through a series of tables in the change of use section (6.31). There are hazard index tables for means of egress, height and area, exposure of exterior walls, exterior wall fire resistance rating, fire suppression, and structural loads, as well as a general, relative hazard index table.

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  • Sets of Requirements

    Sets of Requirements

    The five sets of requirements are products and practices, materials and methods, new building elements, basic requirements, and supplemental requirements

    Products and Practices

    Products and Practices are lists of items that are required and those that are prohibited. These requirements apply to all categories of work. It includes such provisions as the installation of a low flow toilet when an existing toilet is replaced. 

    Materials and Methods

    Materials and methods means what it says—it contains requirements that tell you what materials to use and how to use them. It does not contain requirements on how much fixing you have to do. Materials and methods applies to all categories of rehabilitation except repair. This section was developed by going through all the subcodes and taking out the scoping requirements (the provisions that tell how much work must be done). What was left was materials and methods (what kind of material must be used, how much of the material is to be used, and how the material is to be installed). The materials and methods are identified by referencing specific sections of the particular subcodes. 

    New Building Elements

    This section lists those items which are considered new building elements when they are created as part of a rehabilitation project. Each item listed in this section must conform to specific sections of the other technical subcodes of the UCC, which are listed in the New Building Elements section of the Rehab Subcode. Some examples of new building elements are newly created atriums (an atrium that never existed before), newly created malls in existing buildings, and newly created floor openings. 

    Basic Requirements

    Basic requirements apply only in a reconstruction project and where work is taking place—the work area. The basic requirements are the most fundamental scoping requirements. They cover such topics as capacity of means of egress, dead end corridors and exit signs. The basic requirements are drawn largely from subchapter 4 of the Uniform Fire Code and arranged according to use group. 

    Supplemental Requirements

    Supplemental requirements are additional work requirements. They are imposed only when the work is a reconstruction project, and only when the work area exceeds a certain size. Each supplemental requirement has its own threshold of applicability. The supplemental requirements replace the 50% of the 25/50 rule and are intended to improve the safety at the building in direct relationship with the planned scope of work. Like the basic requirements, the supplemental requirements are arranged by use group.

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  • Categories of Work


    This category is the most minimal type of rehabilitation work. The definition of repair contained in the regulations (NJAC 5:23-6.3) is "the restoration to a good or sound condition of materials, systems and/or components that are worn, deteriorated or broken using materials or components identical to or closely similar to the existing." 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 a few (and only a few) specific exceptions to this rule. They include requiring certain products and practices, such as putting in a low flow toilet when a toilet is being replaced, and prohibiting other items, such as certain electrical materials or supplies. These can be found in the repair section of the regulations at NJAC 5:23-6.4.

    Products and Practices is the only one of the Sets of Requirements that applies to repair. 


    This category is for work that is generally restorative in nature such as the replacement of interior finish, trim, doors, or equipment, but renovation involves the use of different materials. There is no reconfiguration of space. The regulations (NJAC 5:23-6.3) define renovation as "the removal and replacement or covering of existing interior or exterior finish, trim, doors, windows or other materials with new materials that serve the same purpose and do not change the configuration of space. Renovation shall include the replacement of equipment or fixtures." In general, the materials used and the methods of installation must conform to the requirements found in the materials and methods section (NJAC 5:23-6).

    When renovation work is undertaken, then, there are two Sets of Requirements that apply: products and practices and materials and methods. 


    This category of work involves a change in the layout of interior space while other portions of the space remain without rearrangement. Alteration is defined in the regulations as "the rearrangement of any space by the construction of walls or partitions, the addition or elimination of any door or window, the extension or rearrangement of any system, the installation of any additional equipment or fixtures, and any work which affects a primary structural component." There is a short list of materials that may not be used, as well as products or practices which must be used when alteration work is undertaken. The materials and methods requirements also apply to alteration work. To address the possibility that the reconfiguration of space could create a safety hazard, there are some additional requirements for alteration work, which specify that the work undertaken cannot create a nonconformity with the basic requirements that did not exist before the alteration began.

    This is a key issue to understand. In an alteration, the portion of the building being worked on 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 with the basic requirements than it was before the work was undertaken.

    So, there are three Sets of Requirements that apply to an alteration project: products and practices, materials and methods, and basic requirements. 


    This category involves extensive work to the interior of a building, floor, or tenant space. It is commonly referred to as a "gut rehab". The regulations define reconstruction as "any project where the extent and nature of the work is such that the work area cannot be occupied while the work is in progress and where a new certificate of occupancy is required before the work area can be reoccupied." Reconstruction includes repair, renovation, alteration in any combination. Reconstruction does not include projects comprised only of floor finish replacement, painting or wall-papering, or the replacement of equipment or furnishings. Asbestos hazard abatement and lead hazard abatement projects are not classified as reconstruction although occupancy of the work area is not permitted.

    A reconstruction project has a delineated work area. A reconstruction project involves an entire use, primary function space, or tenancy; projects that do not involve an entire use, primary function space, or tenancy are not reconstruction projects.

    Where the work area is an entire use, primary function space, or tenancy, a project becomes reconstruction when two conditions are met: 1) the area where the project is taking place cannot be occupied while the work is in progress; and 2) when a new certificate of occupancy is required before the area can be reoccupied.   

    Repair, renovation, and alteration work that make up a reconstruction project must comply with the requirements for the applicable category of work. The entire area must comply with basic requirements. Certain reconstruction projects must also meet the supplemental requirements, which apply only when the work area for a reconstruction project exceeds a specific size. Each supplemental requirement has its own threshold of applicability. The basic requirements and the supplemental requirements are arranged by use group. 

    A reconstruction project includes three of the Sets of Requirements, products and practices, materials and methods, and basic requirements. It may also include a fourth set of requirements, supplemental requirements, depending on the size of the reconstruction project, and it could include new building elements, depending on the scope of work. 

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  • Change of Use

    The Uniform Construction Code establishes construction requirements according to the way a building is used. The use, or function, of a building is called a use group. The Rehab Subcode also uses these same use groups. The Change of Use section governs what work must be done when a building that has been used for one use is changed to accommodate another use. For example, it details what must be done when a building that has been a store is changed into a restaurant.  

    The amount of work that is required can range from nothing to a great deal. Previously, the Uniform Construction Code provided that any building or portion of a building undergoing a change of use had to meet code requirements for new construction. Under the Rehab Subcode, this has changed. The work required is now dependent on whether a greater hazard is created. In sum, the change of use of a building means a change of the use group as defined in the building subcode or by the provisions of another subcode.   

    The change in the use of a space in a building may not require that the entire building undergo a change of use group, but it may mean, for example, that the change in the way the space is used may trigger the requirements of one of the technical subcodes of the UCC. 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 (HVAC) system be upgraded.  

    There are six hazard tables in the change of use section. It is important to remember in determining whether work must be done that each of the six tables must be consulted. The first table deals with relative use group hazard. This table categorizes all work according to hazard. The next five tables address the following technical issues: means of egress, height and area, exposure of exterior walls, fire suppression, and structural loads. These tables operate independently of one another. There are additional requirements when the work affects vertical openings, fire alarms, fire detection, smoke detectors, or some plumbing, electrical, mechanical, or accessibility provisions. 

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  • Additions

    Additions are required to comply with the provisions of the technical subcodes for new construction of the Uniform Construction Code. Work in the existing building which is related to the addition must comply with the requirements for repair, renovation, alteration, and reconstruction, as applicable, where such work is undertaken.  

    There are also some requirements that apply to additions. For example, the addition cannot extend the height or area of the building beyond the limits established by the rehab subcode.

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  • Historic Buildings

    The Rehabilitation Subcode includes provisions for buildings that meet the standards for historic buildings established by the relevant State or Federal agencies. The Rehab Subcode allows the use of replica materials, establishes provisions for historic buildings used as historic museums, and identifies building elements that may meet relaxed code requirements in order to preserve the historic value and integrity of a historic building.

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  • Administrative Provisions

    As its name implies, the Rehab Subcode is a subcode of the Uniform Construction Code. As Subchapter 6, it is cited as NJAC 5:23-6. Thus, the administrative provisions of the Uniform Construction Code apply to rehabilitation projects, as they do to other construction projects.   

    The Department has become aware that questions have arisen regarding the relationship of the Rehab Subcode, a rehabilitation project, and a construction permit. The Rehab Subcode contains NO provisions for permits; all permit requirements remain where they have always been, in Subchapter 2 of the Uniform Construction Code, NJAC 5:23-2.  

    The Rehabilitation Subcode is a technical subcode and, as with the other technical subcodes, contains only technical requirements. The only changes made to Subchapter 2, the administrative provisions, were the inclusion of the definitions of the new terms used and applied in the Rehab Subcode.

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