Transcript Code-book-and

Building Codes
Contents
Analysis of the organization, intent and use of codes in general and the
International Building Code IBC in particular
Reasons why the codes exist and how they form an integral part of the design
criteria for every building project.
The more you know about the code, the more it can become a tool for design rather
than an impediment. The better the underlying criteria for code development and the
reasons for code provisions are understood, the easier it is to create code-compliant
designs.
Early understanding and incorporation of code-compliant design provisions in a
project reduces the necessity for costly and time-consuming rework or awkward
rationalizations to justify dubious code decisions late in project documentation, or
even during construction.
Brief History
If a builder builds a house for someone, and does not construct it properly, and the
house which is built falls in and kills its owner, then that builder shall be put to death.
(Hammurabi’s Code of Laws, ca. 1780 BC)
Chicago developed a building code in 1875 to placate the National Board of Fire
Underwriters who threatened to cut off insurance for businesses after the fire of
1871.
The first model codes were written from the point of view of insurance
companies to reduce fire risks. Model codes are developed by private code groups
for subsequent adoption by local and state government agencies as legally
enforceable regulations.
Three Model-Code Agencies
The first major model-code group was the Building Officials and Code Administrators
(BOCA), founded in 1915, currently located in Country Club Hills, IL
The International Conference of Building Officials (ICBO) was formed in 1922,
presently located in Whittier, CA. The first edition of their Uniform Building Code was
published in 1927.
The Southern Building Code Congress International (SBCCI) was founded in 1940,
Birmingham, AL. They publish the Southern Building Code.
The ICBO Uniform Building Code
was used West of Mississippi
The BOCA National Building Code
was used North-central, North-east
The SBCCI Standard Building Code
was used Southeast
International Code Council and the IBC
International Code Council (ICC) was formed in 1994 with representatives from
three major model-code groups. Their first achievement, despite differences, was
that the organization of each code became the same, thus allowing direct
comparisons.
International Building Code (IBC) published and maintained by representatives of
three agencies, the International Code Congress, in Falls Church, VA
In addition
International Residential Code (IRC)
Americans with Disabilities Act (ADA). It is a federal civil-rights legislation, an
enforced law, rather than just a code. ADA Accessibility Guidelines (ADAAG)
Federal Fair Housing Act (FFHD)
Adoptions of Codes by States, Counties and Cities
The three major regional differences still exist. For instance, until the IBC was
adopted, Georgia adopted more codes according to the Standard Building Code
Larger cities such as Los Angeles, New York City, Chicago and San Francisco adopt
many revisions to the model codes, sometimes having no basis on the model-codes.
It is imperative to check first what kinds of codes or regulations are adopted by the
county, city or the state in which the project is located.
Specialized Codes | the AHJs
Life Safety Code (NFPA-101) published by the National Fire Protection Association.
This codes serves as the basis for the egress portion of other model codes. Hospital
and federal projects use NFPA-101.
Fire codes are typically considered maintenance codes. They are intended to
provide for the public safety and the daily operation of a structure.
Planning, zoning, fire and building officials that have something to say about building
are known as Authorities Having Jurisdiction (AHJ). Often, there are overlapping or
duplicity of jurisdictions.
It is imperative to determine first which codes and standards are to be enforced for a
project and by which agency.
Legal Basis for Codes | Standard of Care | Priorities
The model codes have no force of law unto themselves. Only after being adopted
by a governmental agency, do they become enforceable under the police
powers of the state, county or city.
Determine what kinds of construction require application of code. Some remodeling
work is exempt from code regulations.
One exception is the ADA which is a civil-rights law and is not enforced by building
officials, while still not relieving the owner from obligations under the ADA.
Codes are legally and ethically considered to be the minimum criteria to be
met.
The basis for building-code development is the safeguarding of the public, while
having a strong component of property protection. Sprinklers help both public and
buildings. Security measures against burglary might interfere with life safety of
occupants.
Future Trends | Performance vs. Prescriptive Codes
At the present condition, the IBC is prescriptive in nature. It is developed to
mitigate concerns by creating specific and prescribed responses to problems
that have been identified. For instance, an assumed problem is falling over an edge
higher then 30” above the adjacent grade. The solution – guardrails of 42” height
are required for differences in grade exceeding 30”. Note: a handrail is not a
guardrail.
Performance codes define the problem and allow the designer to devise a solution.
The word ‘performance’ refers to the problem definition and to setting
parameters for deciding if a solution solves the problem. For instance, ‘the building
shall allow all of its prospective occupants to safely leave the building in case of fire’.
The language of modern performance based codes is an objective-based one.
Objective: What is to be accomplished? (Example, prevention from falling 30”)
Functional Statement: Why do we want this? (We want to safeguard occupants
from accidentally falling from a height that might result in injury)
Performance requirement: How is this to be accomplished? Guardrails. (might
become prescriptive)
2 | Navigating the Code
The key word to remember about how all building codes are developed and how
they work is intent. The intent of the author of a building code section is to solve a
specific design problem with prescriptive words.
Designers also have intent as they are trying to achieve certain functional or formal
goals in the design of the building. Designers should measure their own intent for
the design against their interpretations of the intent of the code. When examined
together, the intent of the code and that of the design solution should be
concurrent.
The responsibility for understanding, applying and fulfilling the requirements of the
code always rests with the design professional. Approvals by the AHJ do not
relieve the designer of social and licensing responsibilities to maintain the health,
safety and welfare of society.
Intent and Interpretation
Each section of the code was developed to solve a certain problem.
Sections are organized into chapters based upon common themes, but usually are
developed in isolation from one another with little attention to continuity of the whole
document.
Code language usually arises from a specific issue the code writer wishes to
address based on experience or upon a construction or life safety issue. The writer
then makes the requirements general so that they apply to more typical conditions
than the specific instance that generated the concern.
The intent of the code is a crucial idea to understand. Why is a much more
important question that what when you are puzzled by the actual language of a
code passage.
Do not try to memorize passages from the code, rather learn the organization of
the code.
Alternate Means and Methods
The alternative is to be approved when “the
proposed design is satisfactory and complies
with the intent of the provisions of this code, and
that the material, method or work offered is, for
the purpose intended, at least the equivalent of
that prescribed in the code in quality,
strength, effectiveness, fire resistance,
durability and safety. ( § 104.11)
Alternate Means
and Methods
Code interpretations
Designers and code officials approach
interpretations from quite different perspectives.
The designer is trying to make his design
solution compliant with the code while satisfying
project requirements.
The AHJ examines the solution for compliance
with the code being unaware about the practical
requirements of the building design.
When differences occur, the designer and AHJ
work together to reconcile the intent of the
design solution with the intent of the code
Documenting Code interpretations
Every project should receive a detailed code
analysis that is recorded as a permanent part
of the permit documents
All code interpretations and citations should
have a reference to the code sections in order
to allow retracting steps in the code analysis
This figures shows the minimum required
items
Also, site plan, floor plan, detail egress
requirements, exit discharge paths, exit
quantities and locations.
Using the Code
1 Classify the building according to occupancy, type of construction, location of
property, floor area, height and number of stories.
A
B
C
D
2 Review the building for conformity with occupancy requirements
3 Review the building for conformity with the type of construction requirements
4 Review the building for conformity with egress requirements
5 Review the building for other detailed code regulations
6 Review the building for conformity with structural engineering regulations and
requirements for materials of construction
E
Classifying the Building
1A
Occupancy Classification
Determine the occupancy group that the use of
building or portion thereof most nearly
resembles.
Compute the floor area and occupant load of the
building or portion thereof.
See appropriate sections in Chapter 3 for
buildings with mixed occupancies.
Classifying the Building
1B
Type of Construction
Determine the type of construction by the
materials used and the fire-resistance of the
parts of the building.
Classifying the Building
1C
Location on Property
Determine the location of the building on the site
and clearances to property lines and other
buildings from the plot plan.
Determine the fire-resistance requirements for
exterior walls and wall-openings requirements
based on proximity to property.
Classifying the Building
1D
Allowable Floor Area
Determine the allowable floor area of the
building.
Use basic allowable floor area (tabular area)
based on occupancy group and type of
construction.
Determine allowable floor area of multistory
buildings.
Determine allowable increases based on location
on property and installation of an approved
automatic fire-sprinkler system.
Classifying the Building
1E
Height and Number of Stories
Compute the height of the building and
determine the number of stories.
Determine the maximum height and number of
stories permitted based on occupancy group and
type of construction.
Determine allowable height and story increase
based on the installation of an approved
automatic fire-sprinkler system.
Code Components
Occupancy Type
Projects are almost always defined based on
occupancy type. A client asks a designer for
facility with a defined need. The use of that
facility determines the occupancy group to which
it belongs.
Each occupancy group has specific
requirements related to allowable area, height
and means of egress with potential construction
types growing out of these requirements.
The codes are fundamentally use (occupancy)
based.
Chapter 3 includes the definitions about
occupancy classification
Code Components
Construction Type
Construction types are categorized with regard to
their resistance to fire in structural applications.
Construction type gives some indication about
the amount of time available for evacuation.
(wood, steel, reinforced concrete). More resistant
construction types are allowed to have more
occupants, larger area, and more stories.
Rule of thumb: occupancy quantities and
construction costs will both decrease with
building type from Type I to Type V.
Chapter 6 and Table 601 gives a synopsis of the
minimum fire requirements of each main
construction element
Code Components
Building or Floor Area
After one knows the occupancy group and
construction type, it is important to establish the
permissible area for each floor, for each use and
for the entire building.
Some types of construction are limited in size
based on occupancy and concentration of
people.
Allowable height and areas are tabulated in
Table 503.
Section 506 shows allowable increases based
on location on the property and allowance for
installation of automatic fire-sprinkler systems.
Code Components
Exits / Egress
Determining egress requirements and provision
of safe means of egress is one of the most
important functions of building codes.
There are specific requirements for size,
spacing and travel distances for all
components such as floor plans, doors,
corridors and stairs.
In simple terms a means of egress consists of
three main components: an exit access, an exit
and and exit discharge.
Code Components
Building Separation and Shafts
In case of mixed occupancies, codes require firerated partitions separating the occupancies.
Separations may also be used to allow more
area for a particular occupancy on a single floor
in certain types of construction where otherwise
such sizes of use would not be permitted.
Openings between floors such as for stairs,
elevators and mechanical shafts can allow the
passage of smoke, heat and flames. Hence,
codes have requirements based on occupancy,
building type and building height related to shaft
protection.
Chapter 7
Code Components
Fire Protection
Fire protection is divided in two broad categories
passive or active protection.
Passive protection is the one built into the
structure, either inherent or added as part of
protective membranes (wood, steel, reinforced
concrete – combustible or non-combustible)
Active protection is the one where the fire causes
a reaction in the systems that serve to combat
the fire (e.g., sprinklers). Code analysis and
design often includes trade-offs between active
and passive systems.
to be continued
Code Components
Fire Protection Standards
continued
Fire Resistive Standards Include:
1 Structure Hour Rating:
Requirements of how long it takes for a fire to
weaken a structural element to the point of
failure. Minimum time for evacuation and firefighting response.
2 Area or Occupancy Separation Rating:
Requirements of how long it will take for a fire to
penetrate a wall partition, floor or roof assembly.
3 Flame Spread and Smoke Generation:
Requirements of how long it takes a fire to move
along the surface of the building and how much
and what toxicity of smoke is generated.
Chapters 7 and 8
Code Components
Fire Extinguishing Systems
Fire sprinklers, standpipes, fire detection and
fire-alarm systems are an integral part of many
buildings. Use of such systems often results in
trade-offs for additional height or area.
Trade-offs only apply when the systems are not
otherwise required by the code. The idea of a
trade-off recognizes that this is a mitigation
measure over and above basic code
requirements to achieve the desired level of
safety different from those spelled out in the
code.
Chapter 9
Code Components
Engineering Requirements
One of the bases of codes is structural adequacy
of building for both static loading such as
occupants and equipment as well as dynamic
loading such as earthquakes, snow and wind
Chapters 16-18 deal with forces, inspections
and foundations
Chapters 19-23 deal with materials: concrete,
lightweight materials, masonry, steel and wood.
Code Analysis
Every Project, no matter how small , should have a code analysis performed!
Wherever possible consult with the building department and other Authorities
Having Jurisdiction prior to design.
Do not expect the code official to do the analysis work for you. Remember,
compliance is the responsibility of the designer, not the code official.
However, codes are subject to interpretation. So it’s always in your best interest to
determine what, if any, interpretations will be needed for a project.
REMEMBER: DO NOT TRY AND MEMORIZE PARTS OF THE CODE!!! As sections
change and interpretations alter meanings, such memorization is a recipe for future
trouble.
Clients may expect you to rattle off code requirements, but it’s not in the best interest
of project or client to do so and possibly make”snap” code decisions.
DO NOT PROCEED ON MEMORY OR ANALOGY FROM OTHER JOBS!
Remember where to look up information and check your decisions each time you
apply them.
Even seasoned code professionals use the index to locate familiar phrases and
locations of information, especially since items are often relocated as the code
evolves.