2021-2024 Building Codes: Roofing Provisions

Are You Prepared for the Changes?

Atlas Roofing
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Building codes are subject to change every three years. According to RoofingContractor.com, “Even roofing products that seem to be grandfathered into the codes may change in your jurisdiction.”

Uniform Evaluation Services, a company within the International Association of Plumbing and Mechanical Officials (IAPMO) group, regularly reviews these tri-annual code changes and subsequently updates product evaluation reports to aid contractors in compliance, so they can avoid questions from building officials.

Are you prepared for and aware of the updates for 2021-2024? Find out now!

First, take Roofing Contractor Magazine’s quiz here.

Then, see the questions and answers* below, along with the associated codes, which can be found in Chapter 9 (Roof Assemblies) of the International Residential Code (IRC) and Chapter 15 (Roof Assemblies and Rooftop Structures) of the International Building Code (IBC).

1. True or False: Roofs that drain over roof edges are required to have separate secondary (emergency overflow) drains.
Answer: False

IRC R903.4.1 / IBC 1502.2

Secondary (emergency overflow) drains or scuppers

Where roof drains are required, secondary (emergency overflow) roof drains or scuppers shall be provided where the roof perimeter construction extends above the roof in such a manner that water will be entrapped if the primary drains allow buildup for any reason. Overflow drains having the same size as the roof drains shall be installed with the inlet flow line located 2 inches above the low point of the roof, or overflow scuppers having three times the size of the roof drains and having a minimum opening height of 4 inches shall be installed in the adjacent parapet walls with the inlet flow located 2 inches above the low point of the roof served. The installation and sizing of overflow drains, leaders and conductors shall comply with Sections 1106 and 1108 of the International Plumbing Code, as applicable.

Overflow drains shall discharge to an approved location and shall not be connected to roof drain lines.

2. Chimney or other penetration greater than ___ inches wide require that a cricket or saddle be installed on the ridge side.
Answer: 30 inches

IRC R903.2.2 / IBC 1503.5

Crickets and saddles

A cricket or saddle shall be installed on the ridge side of any chimney or penetration greater than 30 inches wide as measured perpendicular to the slope. Cricket or saddle coverings shall be sheet metal or of the same material as the roof covering.

Exception: Unit skylights installed in accordance with Section 2405.5 and flashed in accordance with the manufacturer’s instructions shall be permitted to be installed without a cricket or saddle.

3. True or False: Roof recover using asphalt shingles over an existing asphalt shingle roof is not allowed if there are two layers present already.
Answer: True

IRC R908.3.1.1 / IBC 1512.2.1.1

Roof recover not allowed

A roof recover shall not be permitted where any of the following conditions occur:
1) Where the existing roof or roof covering is water soaked or has deteriorated to the point that the existing roof or roof covering is not adequate as a base for additional roofing
2) Where the existing roof covering is slate, clay, cement or asbestos-cement tile
3) Where the existing roof has two or more applications of any type of roof covering

4. For single-family residential dwellings, when is a Class A, B or C roof covering required?
Answer: When so required by local regulations

IRC R902.1

Roof covering materials

Roofs shall be covered with materials as set forth in Sections R904 and R905. Class A, B or C roofing shall be installed in jurisdictions designated by law as requiring their use or where the edge of the roof is less than 3 feet from a lot line. Class A, B and C roofing by this section to be listed shall be tested in accordance with ASTM E108 or UL 790.

1) Class A roof assemblies include those with coverings of brick, masonry and exposed concrete roof deck
2) Class A roof assemblies include ferrous or copper shingles or sheets, metal sheets and shingles, clay or concrete roof tile, or slate installed on non-combustible decks
3) Class A roof assemblies include minimum 16 ounces per square foot copper sheets installed over combustible decks
4) Class A roof assemblies include slate installed over underlayment over combustible decks

5. What materials are allowed for gutters?
Answer: Non-combustible metals and Schedule 40 plastic

IBC 1502.4


Gutters and leaders placed on the outside of buildings, other than Group R-3, private garages and buildings of Type V construction, shall be of non-combustible material or not less than Schedule 40 plastic pipe.

As a roofing contractor, you should be familiar with all international building codes, as well as your local codes. And because codes are often amended, it’s a good idea to check the IRC and IBC for changes at the beginning of each three-year period to help avoid an improper installation that could cost your company time and money.

In addition, Atlas strongly urges contractors to consistently consult and follow all roofing manufacturers’ guidelines to prevent installation issues that could potentially void your customers’ warranties.

For information about Atlas Roofing warranties, visit AtlasRoofing.com.

*All questions and answers are from Roofing Contractor Magazine’s quiz.