You should have finished Study Sessions 1 and 2 and Quick Quiz 2 before starting this Study Session. This Study Session lists some common foundation problems and includes the first part of our foundation cracks discussion.
The estimated completion time is 30 minutes.
Objectives
At the end of this study session, you should be able to:
At the end of this study session, you should be able to:
- List twelve common foundation problems.
- List four types of cracks.
- Describe in one sentence the cause and implication of shrinkage cracks.
- List four characteristics of shrinkage cracks.
- Define control point.
- Distinguish between uniform and differential settlement in two sentences.
- List eight causes of differential settlement.
- List two reasons soil bearing capacity may change after the house is built.
- List five soil problems that can cause differential settlement.
Describe a typical shrinkage crack.
Shrinkage cracks are rarely more than 1/8 inch wide and typically do not involve displacement of the concrete on either side of the crack. Shrinkage cracks usually show up within the first year of the life of a home. Shrinkage cracks do not extend through the footings or up into the structure above. Shrinkage cracks may occur at stress concentration points such as window openings.
Explain the difference between uniform settlement and differential settlement.
In uniform settlement, the entire house moves and no cracking develops. With differential settlement, one part of the house moves relative to another. This typically results in cracking.
Make a list of typical causes of differential settlement.
1. footings that are missing, undersized or deteriorated
2. soil below the building that is disturbed, weak, expansive, eroding, or heaving due to frost
3. increased loads due to snow and ice
4. building additions.
2. soil below the building that is disturbed, weak, expansive, eroding, or heaving due to frost
3. increased loads due to snow and ice
4. building additions.
Name four causes of cracks in foundation walls
1. Shrinkage
2. Differential settling
3. Heaving
4. Horizontal forces
2. Differential settling
3. Heaving
4. Horizontal forces
What causes a shrinkage crack?
Shrinkage cracks are typically caused by natural curing of concrete
What is the main implication of a shrinkage crack?
The implications of shrinkage cracks may be leakage, but not structural problems.
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