Structure Inspection Section#1 Footings and Foundations Quiz#6

You should have finished Study Session 5 and Quick Quiz 5 before starting this Study Session.

The estimated completion time is 45 minutes.

Objectives
At the end of this study session, you should be able to:

• Describe the causes of heaving.
• Describe how to identify heaving cracks.
• Understand the implications of cracks due to heaving.

Explain how adding an exterior basement stairwell can cause a frost-heaving problem.

Adding an exterior basement stairwell can allow the frost depth get below the original house footings. This can lead to frost heave of the house in the area of the stairwell.

Give two causes of frost heaving.

1. Footings are too shallow, saturated soils, increasing the frost depth by insulating basement

2. Unheated house during freezing weather

Is adfreezing a condition that acts directly on the footing, the bottom of the foundation, or the sides of the foundation? Explain.

Adfreezing acts on the sides of the foundation. Frost in the soil bonds to the foundation wall and lifts the wall as the ground heaves.

It is sometimes difficult to distinguish between a settlement problem and a frost-heaving problem. Give a few examples of how you would distinguish between the two.

1. To differentiate between settlement and heaving, check whether cracks are opening, crushing, or sliding type cracks. 

2. If sidewalks, driveways and patios slopw down toward the house, settlement is more likely. If they slope up towards the house, heaving is more likely. 

3. If there is hump in the central part of the house but the columns are not cracked or displaced, the house perimeter is probably settling. If central columns show lots of cracks in the floor area and the floor slopes up toward the column, heaving is more likely. 

4. Are overhead electric wires at a different angle than neighbouring houses?Is the house higher or lower?

5. Check adjacent houses for similar evidence and neighbourhood trends. 

6. Look at the soil line against the building. If the front door sill is below grade level, settling is more likely. If you can see a dirt line six inches above the existing grade, heaving is more likely. 

We can change the conditions on the outside of the house to create frost-heaving problems. Give two examples.

1. Insulating basements, leaving houses unheated, or changing the exterior grade height can lead to frost heaving. 
2. Adding moisture to the soil can also create adfreezing problems.

Frost heaving will only exert a force in a vertical direction.

False

It is not possible for a high water table to cause frost heaving because the drainage tile around the house will handle the water.

False

There must be moisture in the soil to have frost heaving.

True