Footing & Column Size: DIY Project Guide

Embarking on a DIY project that involves structural elements can feel daunting, but understanding the fundamentals empowers you to create a safe and lasting result. Concrete, the foundational material for most footings, exhibits strength that directly impacts load-bearing capacity. Consulting the International Code Council (ICC) guidelines ensures your footing and column design adheres to essential safety standards. A precise measuring tape, a seemingly simple tool, becomes indispensable for accurate layout and form construction. Consider insights from experienced builders like Norm Abram, whose expertise highlights the importance of proper preparation and execution in achieving structural integrity for your footing and column project.

Building a Solid Foundation: How to Size Your Footings and Columns

Embarking on a DIY project that involves structural elements like footings and columns can feel a bit daunting, but with the right information, you can tackle it with confidence! The key is understanding how to properly size these crucial components. This guide breaks down the process in a simple, step-by-step manner.

First and foremost, let’s understand why footing and column size is so critical. Your footings are the base that spread the load of the entire structure onto the soil. Think of them like the feet of your building. Columns, on the other hand, are the vertical supports that carry the weight from above down to the footings. If either is undersized, you risk structural failure – settling, cracking, or even collapse.

Now, let’s structure your "Footing & Column Size: DIY Project Guide" article effectively:

1. Introduction: Setting the Stage (and Expectations)

• Hook: Start with a compelling opening. "Want to build a deck, porch, or small addition yourself? Getting the footings and columns right is non-negotiable. This guide will show you how."
• Brief Overview: Clearly state what the article will cover – sizing footings and columns for DIY projects.
• Importance of Accurate Sizing: Briefly explain the consequences of incorrect sizing (mentioned above).
• Disclaimer: Important! Emphasize that this guide provides general information and should not replace the advice of a qualified structural engineer, especially for complex or critical projects. Always check local building codes.

2. Understanding the Basics: Load, Soil, and Codes

• Defining "Load": Explain the concept of "load" in simple terms. This is the weight the footings and columns need to support. Break it down:
  • Dead Load: The weight of the structure itself (framing, roofing, sheathing, etc.).
  • Live Load: The weight of things added to the structure (people, furniture, snow, etc.).
• Soil Bearing Capacity: This is crucial.
  • Explain what soil bearing capacity is – the soil’s ability to support weight.
  • How to Find It:
    1. Local Building Department: They often have information on typical soil bearing capacity for your area.
    2. Soil Testing: For more accurate information (especially for questionable soil or large projects), recommend hiring a geotechnical engineer for a soil test. This is the best option.
• Building Codes: Stress the importance of adhering to local building codes. They dictate minimum footing and column sizes for specific applications. Contact the local building department.

3. Calculating the Load: A Step-by-Step Approach

This section provides a simplified method for estimating the load each footing and column will bear. Again, emphasize that this is for simple DIY projects only.

• Identify the Area Supported: Explain how to determine the area of the structure that each footing and column supports. A diagram is highly recommended.

• Estimate Dead Load: Provide typical dead load values for common building materials (pounds per square foot – PSF). A table can be helpful:

  Material	Approximate Weight (PSF)
  Asphalt Shingles	2-3
  Wood Framing (Typical)	5-8
  Plywood Sheathing	2-3
  Drywall	2-3

  • Add all material PSF and get a single value.

• Estimate Live Load: Provide typical live load values (PSF).

  Area Usage	Approximate Live Load (PSF)
  Decks	40
  Residential Floors	40
  Roofs (Snow Load)	Varies greatly; check local codes

• Calculate Total Load:

  1. Multiply Dead Load PSF by the area supported. This gives you the total dead load on the footing/column.
  2. Multiply Live Load PSF by the area supported. This gives you the total live load on the footing/column.
  3. Add the total dead load and total live load. This is the total load the footing/column must support.

4. Sizing the Footings: Spreading the Load

• The Formula: Explain the basic formula for footing size:
  • Required Footing Area = Total Load / Soil Bearing Capacity
• Example Calculation: Walk through a complete example, showing how to plug in numbers and calculate the required footing area.
• Shape Considerations:
  • Square Footings: Most common and easiest to construct.
  • Rectangular Footings: Used when space is limited.
• Depth and Thickness: Briefly mention the importance of proper footing depth (below the frost line) and thickness (typically reinforced concrete). Refer to local codes.

5. Sizing the Columns: Vertical Support

• Material Options: Briefly discuss common column materials:

  • Wood: Treated lumber is a common choice.
  • Steel: Provides high strength but requires proper corrosion protection.
  • Concrete: Often used for below-grade applications.

• Column Load Capacity: The capacity of a column depends on its material, dimensions, and length.

• Sizing Tables (Wood Example): Provide a simplified table showing allowable column loads for different sizes of wood columns (e.g., 4×4, 6×6) based on their height. Emphasize that these are examples only and that actual allowable loads vary depending on the wood species and grade.

  Column Size (Treated Lumber)	Maximum Height (feet)	Approximate Load Capacity (lbs)
  4×4	8	4,000
  6×6	10	8,000
  8×8	12	12,000

• Steel and Concrete: Note that sizing steel and concrete columns requires more complex calculations and is best left to a professional.

6. Reinforcement: Adding Strength

• Importance of Reinforcement: Explain why steel reinforcement (rebar) is typically used in concrete footings and columns. It adds tensile strength to the concrete.
• Rebar Size and Placement: Provide general guidelines for rebar size and spacing, but strongly recommend checking local codes for specific requirements.
  • Example: "For typical residential footings, #4 rebar spaced 12 inches apart is common."
• Tie Wires: Mention the importance of using tie wires to secure the rebar cage.

7. Pouring Concrete: The Finishing Touch

• Concrete Mix: Recommend using a concrete mix with a specified compressive strength (e.g., 3000 PSI).
• Proper Consolidation: Explain the importance of compacting the concrete to remove air pockets (vibrating or tapping).
• Curing: Highlight the need to keep the concrete moist for several days to allow it to properly cure and gain strength.

This structure gives you a comprehensive and friendly "Footing & Column Size: DIY Project Guide" that helps readers understand the fundamentals of sizing footings and columns for their DIY projects. Remember to maintain a friendly and encouraging tone throughout!

So, that’s the rundown on figuring out your footing and column size for your project! Don’t be intimidated; take it step by step, double-check your measurements, and don’t hesitate to consult with a pro if you get stuck. Happy building!