Structural Support
Structural Support
Building Problem Solutions
Building Problem Solutions
Building Codes For New Jersey - 2009
by John F Mann, PE
See new article for description of current codes. This article is for use only as reference for previous codes.
Contents
Introduction
Wind Speed Map
New Construction
New Residential Construction; IRC 2009 NJ
Design for Wind Speed of 100 mph or Greater
Modifications to Existing Buildings
Introduction
In general, construction throughout New Jersey is governed by the Uniform Construction Code (UCC), implemented in 1977. UCC regulations, managed and published by the Department of Community Affairs (DCA), Division of Codes and Standards, are available on the DCA web site;
Various links provide access to sections of the UCC and reference codes (see below). Link to the entire UCC is towards bottom of page.
To emphasize, there are no separate municipal building codes in New Jersey.
Each municipality has a separate Zoning Code, which homeowners sometimes confuse with the building code.
DCA has recently revised their web site.
Wind Speed Map
The entire wind speed map for New Jersey, as well as large-scale partial maps along the 100 mph wind speed line, are now available at the following link;
New Construction
For new construction, the UCC references standard national codes, such as the International Building Code (IBC). However, New Jersey also makes extensive modifications to these codes.
As of March 7, 2011, the 2009 editions of the International Building Code and International Residential Code were completely effective, with modifications made for New Jersey. For the previous 6 months ("grace period"), IRC 2006 NJ and IBC 2006 NJ had remained effective if selected by the designer.
In the past, modifications to reference codes were included only in the UCC, which made it necessary to check within the UCC to determine if there might be a modification for any specific provision of the reference code.
For IBC 2009 and IRC 2009, modified versions have been published. Each "New Jersey Edition" includes all New Jersey modifications, but only up to the date of publication. Subsequent modifications must still be checked for within updated UCC regulations.
On the DCA web site (see above), read-only versions of IBC 2009 NJ Edition and IRC 2009 NJ Edition are made available. You can not print out any pages. Copy and paste does not work either. You can order each code from the publisher (International Code Council) at; http://www.iccsafe.org/Store/Pages/default.aspx?gclid=CJm9ld-t4J8CFd4D5QodJUJFGg
New Residential Construction; IRC 2009 NJ
In general, within basic limits noted below, design and construction of a single-family house or townhouse (including attached townhouses) is governed by the International Residential Code (IRC 2015 NJ Edition). However, specific limits are provided at the beginning of Chapter 3 (Building Planning).
The following basic limits are set for use of IRC 2009 NJ;
(1) "Conventional" construction (per R301.1.2 and as defined by extensive code provisions). This applies to the building above the foundation.
(2) Type VB construction (without specific fire protection); Two stories, 35 feet height and 4,800 square feet per floor
(3) Type VA construction (with specific fire protection); Three stories, 40 feet height and 10,200 square feet per floor
(4) With monitored automatic sprinkler system throughout; Three stories and 55 feet height. Area limits per code provisions (R300.2).
Chapters of IRC 2009 NJ are arranged by building elements and systems (foundation, floors, walls, roof, heating). Extensive prescriptive provisions are provided for wood framing and light-gage steel framing.
Type VA and Type VB construction are defined in Chapter 6 of the International Building Code (IBC 2009 NJ).
If the building does not satisfy limits of IRC 2009 NJ, then IBC 2009 NJ is applicable.
For complicated cases, to determine if IRC 2009 NJ is applicable, a licensed architect is most qualified to provide professional evaluation. However, a professional engineer is qualified to evaluate various engineering design requirements, such as for structural elements.
IRC 2009 NJ is essentially a prescriptive code. Extensive tables and diagrams are provided that specify details of construction for wood framing, light-gage steel framing and foundations.
For conditions that are not covered by prescriptive provisions, "engineered design" is required per IBC 2009 NJ (R301.1.3).
Further complication occurs when basic wind speed (per Figure R301.2(4) and Bulletin 03-4 of the UCC) is 100 mph or greater. In that case, the "Design Criteria" of R301.2.1.1 is applicable.
Design For Wind Speed Of 100 mph or Greater
When basic wind speed (per standard wind map) is 100 mph or greater, IRC 2009 NJ specifies that construction "shall be designed by one of the following methods", followed by a list of six design criteria requirements.
Taken literally, this provision appears to mean that design of the entire building must comply with one of the five listed design criteria. However, the intent is most reasonably considered to be that only design for wind resistance is governed by these design criteria.
Application of the listed design criteria requires careful understanding of each criteria.
In IRC 2006 NJ, the requirement for design "by one of the following" did not necessarily make sense, without clarification. In IRC 2009 NJ, there is at least the clarifying statement that "The elements of design not addressed by those documents in Items 1 through 4 shall be in accordance with this code." Although this helps, there remains confusion when construction does not satisfy basic conditions of the code, such that "engineered design" is required, in combination with use of the referenced standards for wind design.
Similar to design for any type of force (load), design for wind resistance requires determination of wind forces, followed by design of building elements to resist those wind forces.
The first design criteria (WFCM; Wood Frame Construction Manual) can be used for wood-frame design that fits conditions of the Manual. Two basic methods of design are provided; by engineering calculation or by prescriptive provisions. Extensive tables are provided for each method. However, as can be expected, not every building condition is covered. This is particularly important for design of braced walls (shearwalls). Many shearwall conditions encountered in actual buildings are not covered by the standard provisions of WFCM.
ASCE-7 includes detailed provisions to determine design loads, including wind pressures. However ASCE-7 can not be used by itself for building design. If standard provisions of IRC 2009 NJ do not apply (for wood construction), then the basic governing code (National Design Specification for Wood Construction; NDS) must also be used. For light-gage steel construction, AISI must also be used.
Design criteria for "concrete construction" and "structural insulated panel", per "provisions of this code", is so ambiguous as to be nearly useless.
Modifications To Existing Buildings
The Rehabilitation subcode of the UCC governs modifications of existing buildings, including additions.
Correct application of "Rehab" code provisions is often confusing, even for design professionals. Careful study is warranted.
The following basic requirements can be summarized.
Modification work (rehabilitation) is classified as "repair", "renovation" or "alteration", with the following definitions taken directly from the UCC;
"Repair" means 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.
"Renovation" means 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.
"Alteration" means the rearrangement of any space by the construction of walls or partitions or by a change in ceiling height, 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 reduces the loadbearing capacity of or which imposes additional loads on a primary structural component.
Removal of any wall is considered "alteration" work, especially a load bearing wall. Major structural work is also considered "alteration" work.
A building permit is required for alteration work. A permit is not required for repair or renovation work.
Existing buildings and building elements are allowed to remain without reinforcement as long as the following conditions are satisfied;
(1) Building or element is in good condition and does not pose any danger. Elements (such as floor joists) may remain even if design capacity is less than design capacity required for new construction.
(2) Building or element will not be modified and there will not be any change of use.
(3) New load from new building element will not be applied.
Of course, reinforcement of existing elements may very well be warranted (even if not required by code) depending on existing conditions. For example, reinforcement of relatively flexible floor joists will reduce deflection and vibration of an existing floor.
Understanding the following definitions is also essential for using the Rehabilitation subcode;
"New building element" means any one of the elements listed in N.J.A.C. 5:23-6.9 that did not exist previously.
"Addition" means an increase in the footprint area of a building or an increase in the average height of the highest roof surface or the number of stories of a building.
"Reconstruction" means 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 may include repair, renovation, alteration or any combination thereof. Reconstruction shall not include projects comprised only of floor finish replacement, painting or wallpapering, or the replacement of equipment or furnishings. Asbestos hazard abatement and lead hazard abatement projects shall not be classified as
reconstruction solely because occupancy of the work area is not permitted.
Note that, for new building element, the meaning of "did not previously exist" is somewhat ambiguous, resulting in confusion among everyone involved. The code should provide examples. In practice, this means (or should mean) a completely new building feature, such as a new deck where there is no deck now or new porch roof where this no such roof now.
Installation of a new porch roof to replace an existing porch roof is most reasonably considered "reconstruction" overall and either "repair" or "alteration" work specifically.
Definition of addition has been clarified from the former definition. However, note that extension of an existing partial second floor, over an existing first story, is not included in the definition of addition unless the "average height of the highest roof surface" is increased.
Provisions of the building codes for new construction (IRC 2009 NJ or IBC 2009 NJ) are applicable for rehabilitation work as required by Rehab code provisions. However, even when the code for new construction is applicable, many of the new construction code provisions are often omitted or modified by Rehab code provisions.
Determination of how or when new construction code provisions apply can be challenging. However, new construction code provisions clearly apply for completely new building features, such as a new addition.
