How to Pour a Concrete Foundation

A concrete foundation is the base for any major structure and will determine the soundness of your structure. Before beginning, you should determine the type of soil that the concrete foundation will rest on, how large the foundation will be, how much concrete and other supplies you will need, and also pay attention to weather forecasts--you will need at least five days of dry weather to ensure the foundation dries and sets properly. You will also need to follow all of your local building codes exactly to be sure you pass inspection for your structure.

Things You'll Need

• Enough 2-inch-by-10-inch boards to structure the layout for footing and foundation walls
• Steel rebar reinforcement
• Anchor bolts
• Wire mesh
• Sand or gravel
• Vapor barrier
• Hammer
• Nails
• Concrete
• Concrete spreader

Instructions

1. Check with your local permits office for the exact specifications required for foundations and structures in your area. These codes will determine how many anchor bolts you will need, how much of a gravel/sand base you will need and how thick your wire mesh and vapor barrier must be.

2. Determine the location for your foundation, and what type of soil is in the location. If you are pouring the foundation into a hillside or in an area with flooding problems, a deep foundation may be needed which may require an engineering expert. However, a shallow design is very common and is typically set about 3 inches deep into the soil for structures like garages, outdoor sheds and some homes.

3. Lay out the structure for your concrete foundation using the 2-inch-by-10-inch boards. Line them up on their sides in order to create a border for your foundation, cutting them to the desired length and nailing them together to keep their shape. To add height to your concrete slab wall, stack multiple boards on top of one another.

4. Install your anchor bolts in the needed locations. These will be used to secure walls to the foundation later on after the concrete has dried and set.

5. Lay the sand or gravel inside the marked-off footing area. The thickness for this base will be determined by local code, but should at least be 3 inches thick to help absorb moisture underneath the concrete in order to prevent water damage to the foundation.

6. Lay the vapor barrier over your sand/gravel to prevent moisture from creeping up into your concrete foundation. Place the wire mesh over where the concrete will be poured.

7. Lay your steel bar reinforcement in the required areas (by local code). These will mostly be required to be near your anchor bolts and outer edges to prevent foundation damage.

8. Pour your concrete over the entire area, being sure to flatten out the slab as it is being poured and working out any air bubbles that appear.

9. Allow the concrete foundation to dry and set for at least five days. This will ensure that the entire center of the structure has set and dried, and prevent any damage to the foundation.

10. Remove the foot borders from your foundation outer edges. The concrete slab will be able to hold itself without any additional support.

References

• Rafter Tales