How far down must you clear roots and stumps before pouring a slab foundation?

When preparing to pour a slab foundation, it is essential to clear roots and stumps to a depth of 12 inches. This practice is crucial for several reasons. Firstly, removing vegetation and organic material, such as roots and stumps, helps to prevent future settling of the slab, which can occur as these materials decompose over time. Decomposing materials can create gaps within the soil beneath the foundation, leading to instability.

Additionally, clearing to this depth helps ensure that the concrete has a solid and stable base for support. Soil compaction is more effective when there is no organic material present, allowing the concrete to withstand loads without shifting or cracking. Thus, clearing down to 12 inches provides the necessary assurance that the slab will rest on a firmly compacted subgrade, enhancing the long-term durability and integrity of the foundation.