STRUCTURAL CRACKS - FOUNDATION MOVEMENT

Foundation Types
The materials for most of the foundations are either stone, concrete block or cast-in-place concrete. Foundation types can be either a slab-on-grade, crawl space, basement or a combination of these.

Horizontal Foundation Cracks
Horizontal cracks in concrete block foundations usually occur in the near center of the foundation walls. These are typically due to soil and water pressure against the foundation walls. Sometimes the bottom concrete block shears at the bottom joint above the basement slab and the wall slides inward. If a concrete porch or steps settle or are anchored to the foundation walls, these can also cause horizontal cracks.
Horizontal cracks in concrete foundation walls are typically due to rusty pieces of steel reinforcing in the foundation walls or exterior porches or stairs that settle and are anchored into the foundation. The very old concrete foundations may have horizontal cracks that are due to cold joints in the concrete, which were due to the bottom portion of the concrete being placed one day and finished the next day.

Vertical, Diagonal and Staircased Settlement Type Foundation Cracks
Foundation settlement usually occurs if the foundation does not penetrate the original soil deep enough through the original soil layer, the supporting soil dries out and shrinks, was not compacted enough to support the building loading or cracked plumbing piping under ground and leaking water into the soil, causing the soil to soften.
Stone and concrete block foundations that start to settle, typically have staircased cracks that offset around the stones or concrete blocks. Also, the concrete block may crack through the block, which is not more serious than a crack that exists around the block. Concrete foundations that settled, usually have vertical or diagonal cracks.

Lateral Foundation Movement
All of these types of foundation may move laterally or sideways. This type of movement may be due to part of the foundation settling, landslides, land slippage or soil pushing against the foundation that has not been anchored into the floor framing. Typically, the floor framing acts as a brace to the top of the foundation wall.

Foundation Corner Cracks
These cracks are seen at the corners of the concrete foundations with brick exterior walls. These cracks are caused by thermal brick expansion (brick expanding due to temperature changes at a different rate than the concrete foundation wall) and no sill flashing or the sill flashing not extended to the corner of the foundation. Without full flashing, the brick bonds to the concrete, expands under warmer temperatures and causes cracks at both sides of the top of the corner of the foundation. This type of movement is considered cosmetic

Basement Seepage or Storm Water Intrusion
Basement seepage may be caused by improperly graded exterior yards - yards that slope toward the foundation, over flowing gutters, damaged or blocked underground piping, leaks through the exterior walls, such as brick veneer or leaks under doors and windows.

Exterior Wall Cracks
Exterior wall cracks typically may occur because of foundation movement, damaged wood framing caused by wood rot or wood-boring insect damage or rusty steel reinforcing or steel lintel supports for brick and stone on brick exterior walls

Interior Cracks, Sloping Floors
Interior wall and ceiling cracks may be caused by foundation settlement or deflection of the floor framing. In older homes with plaster walls and ceilings, sometimes these cracks or even loose plaster may be due to age. Loose plaster on ceilings is a safety concern.

Find the best way to repair your foundation problem by engaging an experienced engineer for an unbiased opinion. Call Mike Montgomery 1-800-285-3001 (scheduling) for review that will diagnose the true problem, recommend a solution and SET YOUR MIND AT EASE.

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