IBC or IRC, that is the question.

The International Code Council (ICC) publishes a variety of model codes. Two of these code books I would like to talk about is the International Building Code (IBC) and the International Residential Code (IRC).

Many people get these two confused and that is quite common. Many times I hear people explain it such that the International Building Code (IBC) is the code book for commercial construction and the International Residential Code (IRC) is the code book for residential construction. This is NOT true.

It is important to know which code book your project is subject to so that the correct regulations are applied. In order to understand this, we must look to the code book themselves.

IBC Scoping vs. IRC Scoping

First off lets look at the International Residential Code (IRC). In order to understand what type of projects fall under the IRC, we must take a look at the scoping section within chapter 1.

Scope of the 2021 International Residential Code (IRC)

Section R101.2 specifies that the provisions of the International Residential Code (IRC) shall apply to detached one-and-two family dwellings and townhouses not more than three stories above grade plane in height with a separate means of egress and their accessory structures not more than three stories above grade plane in height.

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By this code section you can see what falls under the scope of the International Residential Code (IRC) provisions. As for the International Building Code (IBC), let us look at the scoping section within chapter 1 of the IBC.

Scope of the 2021 International Building Code (IBC)

Section 101.2 specifies that the provisions of the International Building Code (IBC) shall apply to every building or structure or any appurtenances connected or attached to such buildings or structures.

As you can see the scope of this code covers every building, however there is an EXCEPTION. The exception states the following:

Detached one-and-two family dwellings and townhouses not more than three stories above grade plane in height with a separate means of egress and their accessory structures not more than three stories above grade plane in height shall comply with the International Residential Code (IRC).

Therefore you can see that the International Building Code (IBC) covers all types of buildings other than those buildings that are subject to the International Residential Code (IRC). For example a detached residential 2-family dwelling structure is subject to the IRC while a detached residential 3-family dwelling structure (not a townhouse) is subject to the IBC.

Another example is a townhouse. A townhouse 3 stories above grade plane is subject to the provisions of the International Residential Code (IRC) while a townhouse 4 stories above grade plane is subject to the provisions of the International Building Code (IBC).

You can see in these examples that residential projects can be subject to the IBC if the project falls outside of the IRC provisions.

When a building does not conform to the prescriptive provisions of the IRC, the building and/or structure is then beyond the scope of the code and the provisions of the IRC cannot be applied and therefore the building must then meet the provisions of the IBC.

Intent of the Code

While the provisions of each code can differ, the intent or purpose of the code is the same: To establish the minimum requirements to provide a reasonable level of public safety, public health, general welfare, and safety to life and property from fire and other hazards attributed to the built environment and to provide safety to fire fighters and emergency responders during emergency operations.

In Summary

The International Residential Code (IRC) applies to the following:

1.Detached one-and-two family dwellings

2.Townhouses not more than three stories above grade plane in height with a separate means of egress.

3.Accessory structures to IRC structures not more than three stories above grade plane in height.

The International Building Code (IBC) applies to all buildings or structures that do not conform to the prescriptive provisions of the International Residential Code (IRC).

Per the International Residential Code, certain rooms within dwellings must be provided with a minimum amount of lighting and ventilation. Section R303 of the International Residential Code (IRC) outlines the requirements to achieve compliance. Before we get into the numbers and how to calculate the required light and ventilation, it is important to understand which rooms within a dwelling are required to comply and which rooms are not.

Habitable Rooms

As stated in section R303.1, Habitable Rooms are required to provide a minimum amount of aggregate glazing area, such as windows, to satisfy the lighting requirement and a minimum amount of openings to the outside to satisfy the natural ventilation requirement.

What is considered a Habitable Room per the Residential Code?

In order to know what is considered a Habitable room, we must look to the definitions found in Chapter 2 of the International Residential Code (IRC).

The IRC defines a Habitable Space as “A space in a building for living, sleeping, eating or cooking. Bathrooms, toilet rooms, closets, halls, storage or utility spaces and similar areas are not considered habitable spaces.”

Therefore given the above definition, the following rooms are considered Habitable:

• Bedrooms
• Living Rooms
• Dining Rooms
• Kitchens
• Family Rooms/Den
• Similar Areas

These spaces are occupied for the majority of the time. Even though toilet rooms, closets, hallway, and similar areas can also be occupied, these spaces are typically considered accessory to the main use and are used when the habitable spaces are occupied.

Now even though Bathrooms are not considered a Habitable Space by the code, there still are some light and ventilation requirements for Bathrooms which we will discuss later below.

Natural Light Calculation Requirements

The aggregate glazing area for a Habitable Room shall not be less than 8 percent of the floor area of the room.

So basically all of the glazing provided in a room added up shall not be less than 8 percent of the rooms floor area. For example if two windows are provided in a bedroom, the size of both windows added together must not be less than 8 percent of the rooms square footage. Lets run through a quick example to better understand this concept.

Lighting Calculation Example

Lets say a 120 square foot Bedroom is provided with a 4’x4′ sliding window:

120 sq.ft. x 8% = 9.6 sq.ft. of glazing area required.

4 x 4 = 16 sq.ft. of glazing provided.

16 sq.ft. provided > 9.6 sq.ft. required OK

Natural Ventilation Calculation Requirements

Habitable rooms must provide openings that total no less than 4 percent of the floor area of the room being ventilated. The openable area shall be open to the outdoors, not another room. These openings can be provided through windows, skylights, doors, louvers, or other approved methods that open to the outside air.

These openings must be easily accessed or readily controllable by the building user. The code does not require these types of openings to remain open constantly but instead that they remain operable and available to the building user when needed.

Lets run through a quick example to better understand this concept.

Natural Ventilation Calculation Example
Lets use the same example above and say a 120 square foot Bedroom is provided with a 4’x4′ sliding window. For the purpose of this example lets say the sliding window is 50% operable, meaning half the window is fixed and other half operable.

120 sq.ft. x 4% = 4.8 sq.ft. of glazing area required.

4 x 4 = 16 sq.ft. of glazing provided.

16 sq.ft. x 50% = 8 sq.ft. operable opening

8 sq.ft. provided > 4.8 sq.ft. required OK

Here’s a graphic of what the above examples visually looks like:

Generally this is how you calculate the natural light and ventilation for habitable rooms. Section R303.1 does have some exceptions regarding the use of artificial lighting and mechanical ventilation which you can read about HERE.

Light and Vent Calculation for Adjoining Rooms

What happens when you have two room adjoining each other? How do you calculate the required light and ventilation for the two rooms?

Or what if a room does not have enough light and ventilation, can you use the light and ventilation provided by the adjacent room?

The answer to these questions can be found in Section R303.2 of the IRC. When trying to determine the light and ventilation requirements for a room, an adjoining room can be considered as a portion of the room first room when the opening between them complies with this Section of the code.

The opening in the common wall between the two rooms must not be less than half of the area of the wall and shall not be less than 1/10 of the floor area of the interior room but at no point less than 25 square feet in area.

Just to recap the opening in the common wall must be:

• Not less than half of the wall area
• Not less than 1/10 of the floor area of the interior room
• Not less than 25 square feet in area

The opening in the wall must meet these parameters in order for two rooms to be considered as one. The opening must also be unobstructed.

Lets run through a quick example to better understand this concept.

Light and Vent Calculation Example for Adjoining Rooms

Lets say a 176 square foot Living Room and a 160 square foot Dining Room share a common wall with an opening adjoining both rooms. The area of the common wall is 128 square feet and the opening within the wall is 84 square feet. Calculate the required light and ventilation for both rooms and check to see if the opening in the common wall is large enough for one room to borrow light and vent from the other.

First off lets check to see if the opening between the two rooms is large enough to borrow light and vent from one another.

Wall Area: 16 ft. length x 8 ft. height = 128 sq.ft.

Opening Area: 12 ft. length x 7 ft. height = 84 sq.ft.

Let run through the 3 checks as outline in Section R303.2

1. Not less than half of the wall area: 128 sq.ft. / 2 = 64 sq.ft. required < 84 sq.ft. provided OK
2. Not less than 1/10 of the floor area of the interior room: 176 sq.ft. / 10 = 17.6 sq.ft. required < 84 sq.ft. provided OK
3. Not less than 25 square feet in area: 25 sq.ft. required < 84 sq.ft. provided OK

All 3 requirements check out which means the opening in the adjoining wall is large enough for the two rooms to borrow light and ventilation from each other.

Now lets see if there is enough Light and Ventilation provided for both these rooms.

Natural Light

Living Room: 176 sq.ft. x 8% = 14.1 sq.ft. of glazing required.

Dining Room: 160 sq.ft. x 8% = 12.8 sq.ft. of glazing required.

Natural Ventilation

Living Room: 176 sq.ft. x 4% = 7.0 sq.ft. of operable opening required.

Dining Room: 160 sq.ft. x 4% = 6.4 sq.ft. of operable opening required.

Now that we know what is required, see the graphic below visually showing the example above and see how much Light and Ventilation is provided.

Generally this is how you calculate the natural light and ventilation for adjoining habitable rooms that share a common wall with an opening. Section R303.2 does have some exceptions regarding rooms that open into a sunroom which you can read about HERE.

Bathroom Light and Ventilation

Even though bathrooms are not considered a habitable room, the code has a separate light and ventilation requirement for them. Section R303.3 requires bathrooms, water closets and other similar rooms to be provided with an aggregate glazing area via a window that is not less than 3 square feet to have enough natural light coming in and at least one-half of the window area must be openable to have enough natural ventilation coming in.

For example a 2’x1′ window in a bathroom would not comply because it is less than 3 square feet. If a 4’x2′ window is used, it will comply since it has an aggregate glazing area of 8 square feet, however 4 square feet of it must be openable to meet the ventilation requirement of section R303.3.

Generally this is how you calculate the natural light and ventilation for bathrooms. Section R303.3 does have some exceptions regarding the use of artificial lighting and mechanical ventilation which you can read about HERE.

Summary of Light and Ventilation Requirements

Lets quickly recap the Light and Ventilation requirements per the International Residential Code (IRC):

1. The aggregate glazing area for a Habitable Room shall not be less than 8 percent of the floor area of the room.
2. Habitable rooms must provide openings that total no less than 4 percent of the floor area of the room being ventilated.
3. An adjoining room can be considered as a portion of the room first room when the opening between them is:
   • Not less than half of the wall area
   • Not less than 1/10 of the floor area of the interior room
   • Not less than 25 square feet in area
4. Bathrooms, water closets and other similar rooms to be provided with an aggregate glazing area via a window that is not less than 3 square feet to have enough natural light coming in and at least one-half of the window area must be openable.

ASTM A350 (ASME SA350) is the standard specification for carbon steel and low alloy steel forged flanges and flanged fittings for low temperature services.

Common use grade is ASTM A350 LF2 Class 1, corresponding material for piping in ASTM A333 Grade 6 and pipe fittings in ASTM A420 WPL6. With yield strength minimum 240 Mpa, and tensile strength in 480 Mpa to 655 Mpa, impact test temperature at -45℃.

Our Supply Range

Grades: ASTM A350/ ASME SA350 Grade LF2, LF1, LF3, LF5, LF6, LF9, LF787, Class 1, 2, 3
Outer Diameters: 1/2'' to 24'' in ASME B16.5, up to 60'' in ASME B16.47
Wall Thickness Schedule: SCH 10, SCH 40, SCH 160 comply with ASME B16.9
Pressure Class: Class 150, 300, 600, 900, 1500, 2500
Manufacturing Standards: ASME B16.5, ASME B16.47 A, B

Standards Scope

ASTM A350 covers several grades of carbon and low-alloy steel forged or ring-rolled flanges, forged fittings and valves intended primarily for low-temperature service and requiring notch toughness testing. They are made to specified dimensions, or to dimensional standards, such as the ASME and API Specifications referenced in Section 2. Although this specification covers some piping components machined from rolled bar and seamless tubular materials, it does not cover raw material produced in these product forms.

Product furnished in ASTM A350/ ASME SA350 shall conform to the requirements of Specification A961/A961M, including any supplementary requirements that are indicated in the purchase order. Failure to comply with A961/A961M will be considered nonconformance with A350. And in case of conflict between ASTM A350 and A961/A961M, this specification shall prevail.

• Weld Neck Flange

• Blind Flange

• Slip On Flange

  STM A350 Flange DatasheetASTM A350 Flange Datasheet

  Chemical Composition
  
  Mechanical Properties
  Tension Tests Requirements—The material shall conform to requirements for tensile properties in below table.

Heat Analysis and Product Analysis
A chemical heat analysis and product analysis in accordance with Specification A961/A961M shall be made and conform to the requirements as to chemical composition prescribed in this table. Leaded steels shall not be permitted. Product analysis

Impact Test Temperature under ASTM A350 Flanges
Test Specimens by 10mm x 10mm

Impact test values: Charpy V-Notch Energy Requirements for specimens 10mm by 10mm.

Referenced Documents

ASTM Standards:

• A788/A788M Specification for Steel Forgings, General Requirements

• A961/A961M Specification for Common Requirements for Steel Flanges, Forged Fittings, Valves, and Parts for Piping Applications
  ASME Standards:

• B 16.5 Steel Pipe Flanges and Flanged Fittings

• B 16.9 Factory-Made Wrought Steel Butt-Welding Fittings

• B 16.10 Face-to-Face and End-to-End Dimensions of Ferrous Valves

• B 16.11 Forged Steel Fittings, Socket-Welding and Threaded

• B 16.30 Unfired Pressure Vessel Flange Dimensions

• B 16.34 Valves-Flanged, Threaded, and Welding End

• B 16.47 Large Diameter Steel Flanges

• ASME Boiler and Pressure Vessel Code
  AWS Standards:

• A 5.1 Mild Steel Covered Arc-Welding Electrodes

• A 5.5 Low-Alloy Steel Covered Arc-Welding Electrodes
  API Standards:

• 600 Steel Gate Valves with Flanged or Butt-Welding Ends

• 602 Compact Design Carbon Steel Gate Valves for Refinery Use

• 605 Large Diameter Carbon Steel Flanges

  Manufacture - Melting and Forging

  Melting Process - The steel shall be produced by any of the following primary processes: open-hearth, basic oxygen, electric-furnace, or vacuum-induction melting (VIM). The primary melting may incorporate separate degassing or refining, and may be followed by secondary melting using electroslag remelting (ESR), or vacuum-arc remelting (VAR).

Discard - A sufficient discard shall be made to secure freedom from injurious piping and undue segregation.

Forging Process
Material for forgings shall consist of ingots, or forged, rolled, or strand cast blooms, billets, slabs, or bars.

Heat Treatment

After hot working and before reheating for heat treatment, the forging shall be allowed to cool substantially below the transformation range.

Forgings grades except Grade LF787, should be heat treated in normalized, or normalized and tempered, or quenched and tempered. By manufacturer's option, material that performed in quenched and tempered could be normalized prior to the austenitize/quenched operation.

No limitation on size is intended beyond the ability of the manufacturer to obtain the specified requirements. However, Class 3 of Grade LF787 is only available in the quenched-and-precipitation heat treated condition.

Hydro-static Test

Forgings manufactured under ASTM A350/ ASME SA350 shall be performed with a hydro-static test compatible with the rating of the finished item. Such tests shall be conducted by the manufacturer only when Supplementary Requirement S57 of Specification A961/A961M is specified.

ASTM A105 is the standard specification for carbon steel forging flanges.

Standard Scope

ASTM A105 covers forged carbon steel flange and piping components for ambient and higher-temperature service in pressure systems. It also includes pipe fittings, valves and similar parts. The maximum weight manufactured forging part follows by this standard is 10000 bounds (4540kg). The larger forgings can according by the standard A 266/A266M. This specification do not covers tube sheets and hollow cylindrical forgings for pressure vessel shells .

This specification does not covers raw material which round bar and seamless tubular produced piping components.

Referenced documents

The following list of standard apply to these specification:

ASTM standards:

• A266/A266M Specification for carbon steel forgings for pressure vessel components.
• A675/A675M Specification for hot-rolled, special quality and mechanical properties, carbon steel bars.
• A696 Specification for steel bars, carbon, hot-rolled or cold-finished,special quality, for pressure piping components.
• A788/A788M Specification for steel forgings, general requirements.
• A961/961M general requirements for steel flange, forging fittings, valve and parts for piping applications.

MSS standard:

• SP44 Standard for steel pipe line flanges
  ASME Standard:

• B16.5 Dimensional standard for steel pipe flanges and flanges fittings

• B16.9 Wrought steel butt-welding fittings

• B16.10 Face-to-face and end-to-end dimensions of ferrous valves

• B16.11 Forged steel fittings, socket weld and threaded

• B16.34 Valves connect by flanges, threaded and welding end

• B16.47 Large diameter steel flanges

• ASME boiler and pressure vessel code:
  API standard:

• API-600 Flanged and butt-Welding-end steel gate valves

• API-602 Compact design carbon steel gate valves for refinery use

Chemical Composition

A The sum of copper, nickel, chromium, molybdenum and vanadium shall not exceed 1.00%.
B The sum of chromium and molybdenum shall not exceed 0.32%.

Mechanical Properties

Elongation

Terminology

For definitions of other terms used in this specification, find in specification A961/A961M.

Ordering information

See specification A961/A961M.

General requirements

If conflict between the requirements of this specification and Specification A961/A961M. Comply with this specification.

Heat treatment

Heat treatment is not required except for flanges above Class 300, flanges of special design where the design pressure or design temperature are not known and for items over 4" NPS and above Class 300. When heat treatment is required, annealing, normalizing, Normalize and temper, normalize and quench and tempering shall be the applied methods.

Welding

These components can be welded. Welding procedures must comply with ASME Boiler and Pressure Vessel Code Section IX.

Forging

ASTM A105 carbon steel can be forged at temperatures in the range of 2200 to 1700 F followed by quenching and tempering or normalizing.

Annealing

Forged parts can be cooled to below 1000 degrees Fahrenheit and then heated to between 1550 degrees Fahrenheit and 1,700 degrees Fahrenheit. Then carry out slow furnace cooling.

Hydro-static Test

Hydro-static Test shall be conducted by the forging manufacture only when Supplemental S57 of ASTM A961 is specified.