How To Lay a Foundation (2024 Guide)
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A solid foundation provides support for the rest of your building project. Whether you’re laying a foundation for a garage, shed, or home addition, this process demands precision.
Our guide offers a step-by-step overview of how to lay a foundation and insight into do-it-yourself (DIY) options. However, in nearly every scenario, we recommend hiring a professional to ensure safety, quality, and peace of mind. Remember, foundations are complex structural elements that leave little room for error.
Steps To Lay a Foundation
Understanding the foundation-laying process is crucial if you plan to go the DIY route. It may also help you understand why we recommend hiring a professional contractor. Below are the basic steps for laying a foundation.
1. Obtain Permits and Materials
2. Lay Out Foundation Footings
Foundation footings are load-bearing structural components that anchor the building to the ground. They must be square, level, and properly sized to distribute the building’s weight evenly and prevent settling or movement. Here’s how to lay out foundation footings:
Step 1: Establish the Layout
Carefully review the construction plans or blueprint for your project. Once the site is level and properly prepared, do a physical walkthrough of the foundation footprint. This will help you understand the layout before you start marking the area.
Step 2: Mark the Corner Points
Mark each foundation corner and drive wooden stakes into the ground at these points. For larger or more complex projects, consider setting up batter boards. These are temporary structures outside the foundation area that provide more stable anchoring points for your layout strings.
Step 3: Set String Guidelines
Attach string or twine to the corner stakes (or batter boards, if using them) and run it along the outer edges where the foundation footings will be. Use a level to ensure the strings are even. Add temporary bracing to the stakes to keep the layout secure during excavation.
Step 4: Check for Squareness
Employ the 3-4-5 triangle method to ensure the foundation corners are square. Measure 3 feet along one string from a corner stake and 4 feet along the adjacent string. The diagonal should measure 5 feet for squareness. Adjust the stakes until you achieve alignment.
Step 5: Mark Footing Locations
Mark the precise locations where you’ll place the footings at regular intervals along the string lines. The proper spacing should be specified in your plans. Footings are often spaced 4–10 feet apart, depending on the building size and soil conditions. For a heavy structure or weak soil, you may need to pour a continuous footing or place the footings much closer together.
Step 6: Excavate the Footings
Dig trenches or holes at each marked footing location using a shovel or excavator. Footings usually extend below the frost line, but the required depth and width may vary depending on soil conditions. Add depth pegs in each trench to show how deep the concrete must be.
Step 7: Install Reinforcement
If your foundation plan calls for reinforcement, such as rebar, position it within the excavated footings. Make sure it’s properly centered and spaced according to your design.
Step 8: Mix and Pour Concrete
Prepare the concrete mixture accordingly and pour it into the footing trenches. Use a concrete vibrator during the pouring process to avoid air bubbles. See “Steps to Follow” below for more tips on working with concrete.
Step 9: Curing and Drying
Allow the concrete to cure and dry. It’s important to maintain a consistent level of moisture during the curing process, which can last several days or even weeks. If concrete dries out too quickly, the foundation will be weaker and more prone to cracking. You can help by misting the concrete with water several times a day for about a week.
For a quick visual demonstration of Steps 6–8, check out the video below. General contractor Tom Silva watches a crew in Charleston prepare for and pour foundation footings for a home addition.
3. Build Foundation Walls
Start the walls by making sturdy forms to use as molds. Pressure-treated lumber works well. The wall forms should match the thickness and height specified in your plans.
Add reinforcement, such as rebar or wire mesh, for added durability.
Prepare the concrete mixture on site and pour it into the forms. Use a concrete vibrator to avoid air bubbles.
Use a screed board to smooth the surface as it dries. Periodically check that the walls are drying plumb and level, making adjustments as needed.
Allow the concrete to cure and dry. Maintain proper moisture levels to prevent cracking.
Once the concrete is completely dry, carefully remove the forms.
4. Pour the Foundation
Once the foundation walls are in place, you can pour a slab foundation if your project calls for one.
Step 1: Mix and Pour Concrete
Prepare the concrete mix accordingly. Begin pouring the concrete inside the foundation walls’ perimeter. Use a concrete vibrator during the pouring process.
Step 2: Smooth and Level
Use a screed board to smooth the surface as it dries. Make sure the foundation is level and make adjustments as needed.
Step 3: Finishing Touches
Apply any finishing touches after the concrete is poured and leveled. These may include troweling the surface for an extra smooth finish or lightly sweeping the surface with a broom to add texture.
Step 4: Curing and Drying
Allow the concrete to cure and dry. Maintain proper moisture levels to prevent cracks in the foundation.
Step 5: Backfill and Complete Project
Backfill the surrounding soil after the foundation has cured and passed inspections. Now you can complete the construction project.
Foundation Types
Choosing the right foundation type is essential for the long-term stability and performance of your building. Different types of foundations have unique benefits for specific needs.
- Basement foundations: Consider a full or daylight basement foundation for extra living or storage space.
Elevated foundations: Crawl space foundations have short walls and provide limited storage space. Pier foundations use posts or beams to elevate the structure.- Slab foundations: Slab-on-grade foundations are cost-effective but not suitable for regions with ground freezing.
- Specialty foundations: Insulated concrete form (ICF) foundations are ideal for energy efficiency and natural disaster resistance. Wood and stone house foundations are less common but have niche uses.
The best type for your project depends on climate, soil type, budget, and structural needs.
DIY vs. Professional
Laying your own foundation is possible but risky, especially if you’ve never done it before. A DIY foundation might be within your capabilities if you have prior knowledge of concrete work and have completed similar projects.
Consider the job’s difficulty level, too. Laying the foundation for a small shed may be easy for you to DIY, but laying the foundation for an entire home is a complex project with much higher stakes.
The main benefit of DIY is the potential for cost savings. Labor costs to build a foundation make up 40%–60% of the total cost. Most homeowners pay between $5,100* and $19,400 for foundation pouring. For the average $9,100 project, you could shave $3,640–$5,460 off the price by doing the work yourself.
Be sure to factor in additional expenses that could offset those savings. For instance, you may need to buy or rent equipment to level the property, dig the footings, and mix the concrete. You may also need to consult a structural engineer, obtain multiple permits, and set aside time for the project.
Hiring a professional foundation contractor might seem pricier upfront, but it typically guarantees higher quality, faster completion, and peace of mind. The structural problems caused by a faulty foundation can be costly and difficult to fix. Look for a contractor who is properly licensed and insured and backs their work with a warranty.
Consult a professional if you’re unsure about your ability to lay a foundation. Remember, the cost of repairing your foundation could be more expensive in the long run than hiring an experienced contractor to pour the foundation.
*Cost data sourced from contractor estimates used by Angi.
Our Conclusion
A strong foundation is essential for any construction project. The process involves obtaining permits, gathering building materials, laying out footings, constructing walls, and pouring the foundation.
Though DIYing can trim labor costs, we strongly recommend hiring a professional to ensure a strong, durable, and long-lasting foundation.
FAQ About How To Lay a Foundation
How do you prepare the ground for a foundation?
To prepare the ground for a foundation, start by clearing the area of vegetation, debris, and unstable soil. Compact the exposed soil and add several inches of gravel as needed to create a flat and stable base. Be sure to excavate below the frost line and plan for proper drainage.
How deep do concrete foundations need to be?
How deep a concrete foundation needs to be depends on the soil type, frost line, and building size. A concrete foundation may only need to be 12 inches deep for a small structure in a warmer climate, while the footings for residential homes typically need to be at least 18–24 inches deep. Be sure to consult the minimum depth requirements set by your local building department.
What is a footing?
A footing is a structural component found at the base of a building. Its primary purpose is to support the building’s foundation and distribute its weight evenly across the soil. Types of footings include shallow footings, pad footings, strip footings, raft footings, and pile footings.
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