Inspecting Foundation Fortitude: Cracking the Code for a Solid Home (IRC R401-R408)

by Nick Gromicko and Ben Gromicko

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A home's foundation is more than just concrete and dirt. Let's dig into the basics of building and inspecting foundations. We’ll refer to Chapter 4 of the International Residential Code (IRC) Chapter 4 and the InterNACHI® Home Inspection Standards of Practice, and translate all that technical stuff into plain talk. 

In this inspection training article, we’ll break down the building code (2024 IRC Sections R401 through R408) and learn how building code can be applied when building and inspecting homes. 

The Foundation: More Than Just Concrete and Dirt

Think of the foundation as the base upon which everything else of the house rests. But it’s not as simple as pouring concrete and calling it a day. Chapter 4 of the building code (the IRC) lays out the rules for building these critical structures, ensuring they stand strong and perform as intended. And the InterNACHI® Home Inspection Standards of Practice requires the inspector to check the foundation, basement, crawlspace, and structural components and report on observed indications of foundation settlement problems and active water penetration. 

Let’s start with the 2024 IRC Section R401, the big picture for foundation types.

For Everyone: The Big Picture (IRC R401)

It’s important to understand that choosing the right foundation is not a one-size-fits-all situation. The picture above is of a crawlspace foundation. That’s what the owner chose to build. The selection of which foundation to build according to code depends on a variety of other factors, including the type of soil, the slope of the lot, and even the local climate. This means every house is unique, and what works for the neighbor might not work for you. Now, the soil under the house itself plays a crucial role. Different soils behave differently. Some dirt holds water, some drain really well, some expand and contract, and some heave and settle. An inspector or contractor can assess these soil conditions to ensure the foundation is properly designed. And all of that is explained in the building code, Sedition R401. Now, let’s move on to Section R402 to R404, the nitty-gritty of building and inspecting foundations.

For the Builders and Inspectors: The Nitty-Gritty (IRC R402-R404)

The IRC specifies the acceptable materials, such as wood, concrete, and masonry, and outlines how these materials should be used. Specifically, R402, R403, and R404 cover material requirements, footings, and foundation wall construction, ensuring there are clear rules to follow. Footings, which can be thought of as the “feet” of a house foundation, are designed to spread the weight of the house. Proper size and placement are crucial for stability. Foundation walls, which can be made of concrete, masonry, wood, or insulated forms, must be strong and resist moisture to prevent structural issues. And that’s all covered in the code sections R402 to R404.

For Homeowners: Keeping Things Dry and Healthy (IRC R405-R408)

Let’s talk about keeping this foundation dry and healthy by resisting moisture intrusion and managing water underground and below the surface. The InterNACHI® Home Inspection Standards of Practice requires the inspector to report on observed indications of active water penetration into the foundation and structure. And foundation drainage and water management are covered in the IRC Sections R405 to R408. Home inspectors can often determine the source of the water problems in a house, and they’re often caused by poor water management. 

Water is a significant enemy of foundations. Water can destroy a house. So, making proper foundation drainage is essential. Foundation drainage for a house includes ensuring correct grading, functional gutters and downspouts, and effective drainage systems to keep water away from a house. Basements and crawlspaces need to stay dry to prevent moisture-related problems, so waterproofing and dampproofing are key. Additionally, crawl spaces require proper ventilation, access, and debris removal to maintain a healthy environment.

Why Should We Care?

Why should we care about all of this technical building code and home inspection standards? 

Every house has a foundation. Even a house on a concrete slab as a foundation. And a solid foundation is the cornerstone of a safe, stable, and healthy home. Foundation problems can lead to costly repairs and compromise the structural integrity of the entire house. Understanding foundation basics empowers homeowners to make informed decisions about their home’s maintenance and potential repairs. That’s why every home should be inspected by an InterNACHI® certified home inspector. Home inspectors educate homeowners, homebuyers, renters, and home builders and contractors on how a home is to be built and maintained so that our homes are safe, functional, and healthy. 

The Bottom Line:

And here’s the bottom line. 

Whether you’re inspecting, building, renting, or owning a home, knowledge of foundation systems is really important to you. To all of us. By understanding the building principles outlined in the building code and having the InterNACHI® Home Inspection Standards of Practice as a guide, home inspectors can help ensure that our homes stand strong for years to come.

For more information about building and inspecting homes, including foundations, visit the International Association of Certified Home Inspectors at nachi.org.

Further Reading

To deepen your understanding of foundation systems and building code requirements, consider exploring these related articles:

1. From Foundation to Roof: Understanding All Types of Code Inspections (IRC R109). Learn the different types of inspections conducted that are listed and described in the International Residential Code (IRC). 
2. Inspecting Foundation Fortitude: Cracking the Code for a Solid Home (IRC R401-R408). Learn how building codes ensure structural integrity of foundation systems.
3. Foundation Fundamentals: Inspecting Load Paths and Water Paths (IRC R401.2 & R401.3). Learn how foundations manage structural loads and water management requirements.
4. Inspecting Footings: The Unsung Heroes Beneath a House (IRC R403). Learn the critical role of properly designed and installed footings.
5. Steel Bones: Inspecting the Critical Role of Rebar in Foundation Strength (IRC R403.1-R403.1.6). Learn how rebar in concrete footings functions as a skeletal framework of steel, providing tensile strength and structural integrity to the foundation.
6. Securing the Perimeter: Inspecting Foundation Anchor Bolts and Sill Plate Protocols (IRC R403.1.6). Learn about the connection between a building's frame and its foundation.
7. Inspecting Frost-Protected Shallow Foundations (FPSF in IRC R403.3). Learn about frost heave, ice lenses, and frost-protected shallow foundations. 
8. Inspecting Foundation Drainage: Essential Guideline for Below-Grade Spaces (IRC R405). Learn how to inspect subsurface drainage systems that collect and redirect groundwater away from the foundation. 
9. Inspecting Foundation Dampproofing and Waterproofing (IRC R406). Learn the difference between dampproofing and waterproofing and how to inspect each foundation drainage system. 
10. Inspecting the Concrete, Cracking, and Water Connection (IRC R406). Learn the connection between concrete, cracks, and water. 
11. Understanding Efflorescence and Spalling: Critical Assessment Points for Home Inspectors.
12. Inspecting Under-Floor Crawl Spaces: A Guide for Home Inspectors (2024 IRC Section R408)

These resources provide information that will give home inspectors, building code inspectors, and contractors a well-rounded understanding of how a home is built safe, functional, and healthy. 

More Information

• Free, Online ICC-Approved CEU Courses
• 2023 Florida Residential Building Code Course
• Property Maintenance and Housing Code Inspector Course
  
• Advanced Residential Code Inspection Practice Questions
• 2021 International Residential Code® (IRC®) Exam Study Course
  

To learn more about homes, inspections, and building standards, visit www.nachi.org/education. 

To become a certified home inspector, visit www.nachi.org/certifications.

Join the International Association of Professional Contractors.