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NEW BUILDING CODE INFORMATION FOR 2016 - The City of Chicago Department of Buildings has released a code memorandum regarding roof requirements on 6/20/2016. Learn More...

NEW Energy CODE INFORMATION FOR 2016 - The State of Illiinois & City of Chicago have adopted the 2015 International Energy Conservation Code as of 5/10/2016.

The State of Illinois Office of Energy & Recycling's Consultant Darren Meyers and CRCA have had many conversations about the Minimum (min) R's of Continuous Insulation (ci) is required for various types of roofs. Below is a short summary and then, the long answer to many of your questions.

  • New Construction - Commercial Occupancies - Insulation Entirely Above Deck - Min. R-30ci.
  • New Construction - Commercial Occupancies - TAPERED Insulation Entirely Above Deck -                              Min. R-30ci. For 1/8" in 12", only a 1" thickness reduction is allowed, 8' from drains.  For 1/4" in 12" slope, a 1" thickness reduction is allowed 4' from the drains. Tapered insulation is MINIMUM R-30ci, and NOT AVERAGE THICKNESSES. This applies to the City of Chicago and State of Illinois Energy Codes.                           
  • Existing Buildings - Commercial Occupancies
    Roof Recover - Adding a cover board over an existing roof, does NOT trigger the Min. R-30ci.
    Roof Covering 'Peel/Replace' - This operation DOES trigger the Min. R-30ci.
    Roof Replacement - This triggers the Min. R-30ci.
  • Existing Buildings - "NO ROOM FOR Min. R-30 ci INSULATION - Flashing heights can be a limiting factor in the thickness of insulation. Should there be many rooftop units, low windows at perimeter, doors at rooftop structures, low flashing heights that cannot accomodate Min. R-30ci, there may be a "Technical Infeasibility", which may be awarded a variance by the Authority Having Jurisdiction, (AHJ). The AHJ is the Building or Code Official at each municipality. There are no 'blanket exceptions'. All exceptions are granted by teh AHJ. 

The info below is From Darren Meyers a/o May 11, 2016. Darren is with International Energy Code Consultants and represents the Illinois Office of Energy and Recycling. From Darren, we received the following 'interpretations':

On issues pertaining to reroofing, roof recover, and roof replacement defined by the International Building Code (IBC) and the Illinois Energy Conservation Code (IECC), only items altered or affected by alterations, renovations or repairs to an existing building are required to conform to the provisions of the code as they relate to new construction.  These definitions are integral to our interpretation:

1) REROOFING. The process of recovering or replacing an existing roof covering. See “Roof recover” and “Roof replacement.”  This definition is the primary term from which “RECOVER” and “REPLACEMENT” are derived.

a)   ROOF RECOVER. The process of installing an additional roof covering over a prepared existing roof covering without removing the existing roof coveringSection C503.1, Exception 5 addresses the issue. The new work must result in a roof assembly insulation level that is not less than the pre-existing R-value.

CRCA NOTE: Recovering an existing roof covering (aka roof membrane) does not trigger the Min. R-30ci. However, the 'peel' of a top roof covering, then roofing over another roof covering, is not allowed based on the definition of roof covering. 


b) ROOF REPAIR. Reconstruction or renewal of any part of an existing roof for the purposes of its maintenance. Section C504.1, Exception 2 addresses the issue. The new work must result in a roof assembly insulation level that is not less than the pre-existing R-value.

CRCA NOTE: Roof Repairs are limited to a certain amount of work on a structure. If in doubt, contact the Authority Having Jurisdiction, (AHJ), the municipalites building or code official.


2) ROOF REPLACEMENT. The process of removing the existing roof covering, repairing any damaged substrate and installing a new roof coveringMust comply with flat roof insulation requirement of R-30ci (Assembly U-factor 0.032), unless the AHJ determines that the installation of insulation above the structural roof deck, and necessary to achieve a code-required R-30ci (U-0.032), is deemed “technically infeasible” to accommodate the added thickness (i.e., HVAC or skylight curbs, flashing heights, VTR, drainage patterns, gravel-stop roof edges, or parapets).

  • TAPERED INSULATION. The minimum R-30ci [Table C402.1.3] applies to the area-weighted average U-factor (U-0.032) from Table C402.1.4 for the tapered insulation assembly. However, at no point (i.e., at roof drains) is the thickness of insulation to vary more than 1-inch (25 mm) from the required minimum R-30ci. For instance, if the density of the insulation were R-5/in., and the code-required minimum R-value were R-30ci, then the minimum thickness of insulation permissible at roof drains (i.e., where the taper starts) would be 5-inches (i.e., 6-in. x R-5/in. = R-30ci; 5-in. x R-5/in. = R-25ci).

 Put another way, Exception 2 to Section C402.2.2 (highlighted) is such that a deficit of no more than 1-inch of insulation is allowed at any point within the roof field [i.e., provided the field is thickened elsewhere to compensate for areas where insulation levels are less than the minimum R-value (thickness in inches) required], such that the overall, area-weighted average insulation U-factor for the entire roof field achieves the minimum U-factor equivalent to the R-value specified in Table C402.1.3. We see the exception allowing a degree of latitude, while requiring a minimum level of insulation over the entire roof field so as to minimize issues of condensation and energy performance for this particular assembly.


C402.2.2 Roof assembly. The minimum thermal resistance

(R-value) of the insulating material installed either

between the roof framing or continuously on the roof

assembly shall be as specified in Table C402.1.3, based on

construction materials used in the roof assembly. Skylight

curbs shall be insulated to the level of roofs with insulation

entirely above deck or R-5, whichever is less.

1. Continuously insulated roof assemblies where the

thickness of insulation varies 1 inch (25 mm) or

less and where the area-weighted U-factor is

equivalent to the same assembly with the R-value

specified in Table C402.1.3.

2. Where tapered insulation is used with insulation

entirely above deck, the R-value where the insulation

thickness varies 1 inch (25 mm) or less

from the minimum thickness of tapered insulation

shall comply with the R-value specified inTable C402.1.3.

3. Unit skylight curbs included as a component of a

skylight listed and labeled in accordance with

NFRC 100 shall not be required to be insulated.

Insulation installed on a suspended ceiling with removable

ceiling tiles shall not be considered part of the minimum

thermal resistance of the roof insulation.

CRCA NOTE: When the roof covering (membrane) is removed, it is considered a roof replacement. This means that even if the insulation is not replaced, a Min. R-30ci is required. That action - 'peeling the roof covering, aka, roof membrane, triggers the requirement for insulation to be Min. R-30ci. 

CRCA Staff Note: All variances are from the local Authority Having Jurisdiction.  The Illinois Energy Office may also be involved in granting variances with the local buildnig or code official. 

CRCA STAFF NOTE - 12/14/2015: The State of Ilinois is moving to the 2015 International Energy Conservation Code if the Joint Committee on Adminstrative Rules votes in favor on Dec. 15. Once we know the effective date, we'll update this page and others to reflect the new codes.

Chicago Department of Buildings - NOTE: The City of Chicago have adopted the 2015 International Energy Conservation Code as of 5/10/2016.

Chicago Department of Buildings - CURRENT 2016 Questions & Answers for a new ordinance coming in 2016

The information below is from the City of Chicago's Buildng Department:

Amount of insulation:  The energy conservation code does not require an expanded scope of work to address the required amount of insulation.   If there are restrictions preventing the full amount of insulation, such as a parapet or equipment curb height or a drainage issue, the code does not require the scope to be expanded to increase those heights for the amount of insulation.  The amount of required insulation is reduced to address those existing conditions.   The amount of insulation to be installed is a minimum of R-3.5 per inch (the draft ordinance for the city of Chicago will include the minimum as R-5 per inch). 


Number of layer of roofs:   Our code does not state the number of layers of roofing allowed.  It requires that the structure be adequate to support the weight of the roof.   Therefore, the department requires a structural engineer’s signed report verifying that the existing structure has the capacity for additional weight if there is more than 2 layers of roofing.  This is also a condition if the intention is to remove only one side of a gable roof.  The asymmetrical loading as a result will need to be confirmed with a structural report.    

Ice and water shield - Ice barrier:   The Chicago building code is a performance based code, not prescriptive.  The  code states that the building must be kept dry; it does not say how to do that.   Therefore, the city of Chicago uses the contractor warranty to enforce the requirement.  If the contractor will not warranty the roof, we do not consider it to have complied with the code of keeping the building dry.  Therefore, if the contractor requires Ice and Water shield to warranty the roof, then it is required. 


Elizabeth Scanlan, RA, LEED AP

Director of Code Development, Department of Buildings, City of Chicago



According the State of Illinois, adoption of the 2012 International Energy Conservation Code is complete.  Legislation passed in 2012 with the Governor's signature increasing insulation requirements by 20%.  Plus, there's a new twist. There is now a 'air barrier' required in new construction.  For Roof Recover, Roof Replacement and Roof Repairs, there are times when R-25 and the air barrier are not required.

CRCA's Industry Affairs Committee and Leadership worked with the IL Capital Development Board to provide relief for building owners and managers in Roof Recover, Roof Replacement and Roof Repairs. The result of these CRCA Efforts resulted in State of IL 2012 Energy Code 'clarifications' published at the State of Illinois Department of Commerce and Economic Opportunity. These are justification statements to be provided the AHJ at each building municipality for approval prior to building permit being issued for existing buildings. 

The effective date of the new IL Energy Conservation Code based on the International Code Council's International Energy Conservation Code is January 1, 2013, not the July 1, 2012 that was first reported in 2011.

For futher information, visit CRCA's Members Only Section of 

If you not a CRCA member, join CRCA to gain access to info that helps raise your knowledge to service customers better!

If you are a specifier, architect or roof consultant, Email CRCA for CRCA's complete 2012 Illinois IECC information.

Building Code Information

From a Building and other Code perspective, Illinois is a 'home rule' State.  As such, each community has the ability to adopt or adopt and amend a model building and other codes. 

In the Chicagoland Area, there are several building , residential, plumbing, mechanical, electrical, existing building and fire codes that may be adopted by a municipality through the local legislative process..

City of Chicago - The Chicago Building and Fire Codes are used by the city providing minimum regulations for structures within the jursdiction.  The code is available for purchase from Index Publishing at

Most of the roofing related items, including the Urban Heat Island Effect Mitigation requirements, insulation minimum thicknesses, and more are in the 2009 Chicago Energy Code. There are some requirements in the Building and Fire Code as well related to roofing.

For 2012, there is a new twist.  The 2012 Inernational Energy Conservation Code (IECC) becomes Illinois State Law 1 year from the date of publication from the International Code Council (ICC) due to legislation similar to Americans with Disabilities Act. On January 1, 2013....the International Energy Conservation Code became State Law. 

CRCA Submitted comments about the IECC 2012 insulation and air barrier requirements to the CDB, IL Energy Conservation Comission and the IL Joint Committee on Administrative Rules (JCAR) which resulted in several 'Clarifications. 

SEE 2009 Chicago Energy Code FOR COMPLETE REQUIREMENTS, as it may vary.

Still not sure?  Contact a CRCA Professional CRCA Professional Roofing Contractor or CRCA's office for more info.

Chicago Suburbs & Illinois - Most of the Chicago Suburbs and the rest of the State of Illinois have adopted versions of the International Code Council's International Building Code, International Residential Code, and International Fire Code, depending on the jurisdiction. The minimum State of IL Fire Code is NFPA 101, The Life Safety Code. 

Verify with each Authority Having Jurisdiction what code is enforced in that community, as it may vary.

Key code points:

Interational Family of Codes
Chapter 15
of the International Building Code covers Roofing issues, while Chapter 16 covers wind uplift, and structural issues pertaning to the roof. 

Included in the International Building Code Chapter 15, 'Roof Assemblies and Rooftop Structures' are requirements for Low and Steep Sloped Roofs and more.

The International Fire Code (2012 version, published in 2011) addresses Vegetative Garden Roofs and Photovoltaic Solar Panel requirements when these systems are placed on or integrated into roofs.

The International Energy Conservation Code (IECC) governs the insulation requirements for roofs. Generally in the Chicago Area, the 2009 IECC Climate Zone 5 charts call for an R-20ci insulation on low sloped commercial type roofs.  There are allowances for tapered insulation.  Consult the IECC code for specific requirements.

The International Energy Conservation Code 2012 has been adapted in the State of Illinois effectve Jan. 1, 2013.  This new code increases R-Values to R-25 for 'commercial' roofs and requires a continous air barrier on the roof. For exceptions, visit the CRCA Members Only Section. If you are an archtiect, specifier, roof consultant, contact CRCA for the 'clarifications' from the State of IL on these important topics.

The International Green Construction Code adds even more R-Value to base code requirements.  Watch for completion of this International Green Construction Code, published March, 2012.

SEE CODE FOR COMPLETE REQUIREMENTS, as it may vary by jurisdication and version of the code.

Key Code Points:

NFPA Codes

NFPA 101, The Life Safety Code, in Chatper 7 and 11 cover means of egress and exit access, plus membrane structures.

NFPA 5000, the Building Construction and Safety Code covers roofing in Chatpers 1, 2, 3 (Definitions), 4, 7, 8 (Insulation-but requirements are in NFPA 900), 11, 13, 15 (Reroofing) and Chapter 34, 35, 38, 45, 48. 

CRCA is not an Authority Having Jurisdiction, and places this information for the benefit of the roofing industry. CRCA is not responsible for use of this information.  See CRCA Terms and Conditions of use for this website for comlete disclaimer. 


Consult the CODE DOCUMENTS FOR COMPLETE REQUIREMENTS, as it may vary by jurisdication and version of the code.

Contact a Professional CRCA Roofing Contractor for more info.

For information about or to purchase these codes, contact the International Code Council, or the National Fire Protection Association (NFPA). 


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