If you are not talking about television, then it stands for Concrete Block Structure, and means the exterior structural walls are concrete blocks that are 8” high by 8” wide by 16” long. There are other sizes available, but 8x8x16 blocks are standard. The blocks have holes in the center which, although they make them lighter and easier to handle, are primarily there to create long vertical shafts in the wall that can be filled with concrete and reinforcing steel at strategic locations to strengthen the wall against lateral (sideways) loads. A stucco finish is usually applied to the exterior of the block wall after the mortar joints have cured, but we have seen CBS houses with brick or shiplap siding applied over the block walls.
A stucco finish on the exterior walls does not automatically mean that the house is CBS construction. Some stucco-finish houses are wood frame structures. Others are half CBS: the first floor is concrete block and the second floor is wood frame with stucco over metal lath. When a two-story home is half CBS, you will see a one-inch bump-out at the middle of the wall where the underlying structures change.
Also see our blog post What are the pros and cons of concrete block versus wood frame construction?
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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?
• 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 common problems of different types of house foundations?
• What are the warning signs of a dangerous deck?
Visit our EXTERIOR WALLS AND STRUCTURES page for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.