Structure Inspection Section#1 Footings and Foundations Quiz#7

You should have finished Study Session 6 and Quick Quiz 6 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 how to identify cracks due to horizontal forces.
• Understand the implications of cracks due to horizontal forces.
• Describe the common causes of cracks due to horizontal forces.

In your own words, give a definition of lateral support as it applies to foundations.

Lateral support is usually a floor system secured to the top of a foundation wall, preventing it from tipping inward.

List five things that could cause horizontal forces on a foundation.

1. Frost pressure 
2. Hydrostatic pressure 
3. Vehicle loads adjacent to the building 
4. Expansive soils 
5. Tree roots 
6. Impact damage

Often horizontal forces will cause horizontal crack in a foundation wall. Why might the crack disappear near the edge of the wall?

The perpendicular wall reinforces the cracked wall near the end, preventing it from moving.

There are seven possible corrective actions where lateral forces have caused cracking, bowing, bulging, or leaning of the foundation wall. Give five.

1. Buttresses are added on the inside of the foundation wall

2. Pilasters are added on the inside of the foundation wall

3. Wood or steel beams or channels are added on the inside of the foundation wall, most often spanning from top to bottom

4. A seperate interior wall is built against the foundation wall in the basement

5. A seperate exterior wall is built against the foundation on the outside (sister wall)

6. Helical anchor screws may be turned into the soild outside the house with interior plates holding the foundation wall from moving inward further. These act like the tie-backs in a conventional retaining wall system

7. Removal of the water from the soild outside the foundation

What is the difference between a buttress and a pilaster?

A buttress is a large structural mass placed against a wall to resist horizontal movement. It can be above or below grade. A pilaster is a vertical thickening of the wall. It may act as a reinforcing beam for the foundation wall and is often designed to carry concentrated vertical loads.

Why might a damaged foundation wall start to move suddenly after a heavy rain?

Increase in hydrostatic pressure, or swelling of expansive soils.

A bow or bulge in a concrete foundation wall is a result of forces that are applied over a very short period of time.

False

Cracks, due to horizontal forces, rarely result in a structural problem.

False