Preparing a Lot for Concrete Slab in Houston

Slab-on-grade construction is the dominant foundation type in Houston. Preparing the lot for a concrete slab requires precise grading, proper soil management, and equipment capable of handling Houston's expansive clay. This guide covers the site preparation process from the equipment operator's perspective.

Houston Slab Foundation Basics

Most Houston residential foundations are post-tensioned concrete slabs poured directly on prepared grade. The slab sits on a layer of prepared subgrade that must meet specific compaction and elevation requirements. The compact track loader's role in this process is clearing the site, establishing rough grade, and preparing the subgrade surface for the foundation contractor.

Step 1: Site Clearing

Before grading begins, the lot must be cleared of vegetation, debris, old foundations (for tear-down rebuilds), and organic material. A compact track loader with a grapple attachment handles most clearing tasks. For lots with trees and heavy brush, a mulcher attachment on the Bobcat T76 processes vegetation without requiring separate hauling.

Remove all organic material from the building footprint. Organic matter decomposes under the slab, creating voids that lead to settlement. Houston lots with mature trees may have extensive root systems that must be extracted from the clay.

Step 2: Rough Grading

Rough grading establishes the approximate elevation for the finished slab. The compact track loader cuts high spots and fills low spots to create a uniform surface within 2-3 inches of the target elevation. In Houston, this typically means achieving positive drainage away from the building pad while maintaining the elevation specified on the foundation plan.

Houston's clay soil presents specific challenges during rough grading. The clay's volume changes with moisture content, so grade established during dry conditions will shift when the soil absorbs water. Experienced operators account for this by slight over-cutting during dry periods, knowing the clay will swell slightly when moisture returns.

Step 3: Subgrade Preparation

After rough grading, the subgrade must be prepared for the slab. This involves verifying that the clay is at the proper moisture content for compaction, removing any soft spots, and creating a uniform surface. The structural engineer's soil report specifies the required compaction density and moisture range for the Houston clay at your site.

Equipment Selection for Slab Prep

For residential slab prep on standard Houston lots (5,000-10,000 sq ft), the Bobcat T450 handles clearing and grading efficiently. For commercial slabs or larger residential lots, the T76's additional capacity speeds up material movement. Both machines' tracked undercarriages provide the stability needed for precision grading on clay.

A GP bucket is the primary attachment for slab prep grading. An auger may be needed for pier holes if the foundation design includes drilled piers — common in Houston for areas with known foundation movement.