You should have finished Study Session 3 and Quick Quiz 3 before starting this Study Session. This Study Session covers causes, implications and inspection strategy for differential cracks as well as some common corrective actions.
The estimated completion time is one hour.
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 nine implications of differential cracks.
- Define the maximum lot slope.
- Describe in two sentences cut and fill lots.
- Define in two sentences how crack size can be misleading.
- Describe three planes of differential movement that result in cracks.
- Describe in one sentence pyramid cracks.
- Describe in one sentence V-shaped cracks
- List four things you may recommend to clients with respect to cracks.
- List six structural repair strategies.
In your own words, explain what a cut-and-fill lot is and what implications this might have on building settlement.
A cut-and-fill lot is a side-hill lot where some of the hill is cut away to allow part of the house to fit into the hillside. The excavated material is often used to fill in the lower part of the slope and create a level pad for the rest of the home. Part of the house sits in the cut area and part of the home sits on the filled area. The filled area is disturbed soil and is more likely to settle.
It is a good idea to inspect the neighbourhood as you are arriving at an inspection. What kinds of things should you look for and how can they help you in your inspection?
1. Look for structural problems in other homes in the neighbourhood.
2. Check the general topography.
3. Houses on side-hill lots may be subject to cut-and-fill type settlement problems.
4. Houses near the bottom of slopes may experience flooding problems.
5. The general age of the neighbourhood is useful information.
6. Older neighbourhoods provide a more reliable test of time.
7. You also may know about specific problems such as expansive or weak soils, high water tables, underground streams or reclaimed land.
2. Check the general topography.
3. Houses on side-hill lots may be subject to cut-and-fill type settlement problems.
4. Houses near the bottom of slopes may experience flooding problems.
5. The general age of the neighbourhood is useful information.
6. Older neighbourhoods provide a more reliable test of time.
7. You also may know about specific problems such as expansive or weak soils, high water tables, underground streams or reclaimed land.
There are a number of clues that might indicate to you that a crack is active. List as many as you can.
1. Opened patches
2. Cracks with no paint in the cracks (if paint is in the crack and the paint is old, the crack existed before the paint was applied)
3. A lack of dirt and debris in the crack (old cracks are often largely filled with dirt and debris)
4. Sharp corners on cracks (old cracks are often worn and rounded)
2. Cracks with no paint in the cracks (if paint is in the crack and the paint is old, the crack existed before the paint was applied)
3. A lack of dirt and debris in the crack (old cracks are often largely filled with dirt and debris)
4. Sharp corners on cracks (old cracks are often worn and rounded)
What is underpinning and in what situation would it be used?
Underpinning is re-supporting footings from below. This can include new foundations and footings, helical anchors, or piles. Underpinning is used in situations where differential settlement has to be stopped. Before underpinning, there should be some confidence that the soil below the building can support the underpinnings.
If you identify a foundation crack, is it possible to determine the rate of movement at the time of the inspection?
No
In general, which crack would be more serious?
A crack that has moved in two different planes
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