A slab on grade home has the foundation and floor slab poured as one piece, with the areas where the walls supporting the roof bear on the slab being thickened from 4” to 10” or 12” deep. Steel reinforcing bars are also added. The thickened areas are created by either digging deeper into the soil or adding fill to raise the area under the 4” floor slab. It’s also called a monolithic slab foundation or a thickened edge slab foundation. An example of this type of foundation is shown above and in the diagram below.    This is the most common type of house foundation in Florida and most of the warmer areas of the country. Before the innovation of a combination foundation and floor slab in the 1950s, a continuous trench was dug in the ground for a concrete footing, as shown below, with a block wall built on top of it.

    To learn more, see our blog posts What is the minimum depth below ground of the foundation of a house, for either monolithic thickened edge slab or stemwall footing? and What are the common problems of different types of house foundations?

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To learn more about exterior walls and structures, see these other blog posts:

• What is the average lifespan of a house foundation?

• What causes vertical cracks in fiber cement siding planks?

 • What causes raised white lines of residue on a block wall that are crusty and crumbling? 

• What is the difference between soil subsidence, heave, creep, and settlement? 

• How much ventilation is required for the under-floor crawl space of a home? 

• What causes stair-step cracks in a block or brick wall?

• What causes a horizontal crack in a block or brick wall? 

• How can I tell if a diagonal crack in drywall at the corner of a window or door indicates a structural problem?

• What causes the surface of old bricks to erode away into sandy powder? 

• What are the pros and cons of concrete block versus wood frame construction?

• Should I buy a house with a crawl space? 

• Why is my stucco cracking?

• There's cracks running along the home's concrete tie beam. What's wrong? 

• What would cause long horizontal lines of brick mortar to fall out?

• How do I recognize structural problems in a retaining wall? 

• What is engineered wood siding?

• Should I buy a house that has had foundation repair? 

• What is a "continuous load path”?

• Should I buy a house with asbestos siding?   

• How can I tell if cracks in the garage floor are a problem or not? 

• What do you look for when inspecting vinyl siding?

• Why is housewrap installed on exterior walls under the siding? 

• How do I recognize serious structural problems in a house?

• Why did so many concrete block homes collapse in Mexico Beach during Hurricane Michael? 

• How can I tell if the concrete block walls of my house have vertical steel and concrete reinforcement?

• Should I buy a house with structural problems? 

• What are those powdery white areas on my brick walls?

• What causes cracks in the walls and floors of a house?

• How can I tell if the exterior walls of a house are concrete block (CBS) or wood or brick? 

• What are the warning signs of a dangerous deck?

   Visit our EXTERIOR WALLS AND STRUCTURE page for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.