Skip to main content
Geology LibreTexts

15: Mass Wasting (Exercises)

Q15.1 Sand and water

Responses will vary

Q15.2 Classifying Slope Failures

[SE]

Q15.3 How Much Does a House Weigh and Can It Contribute to a Slope Failure?

A typical 150 m2 (approximately 1,600 ft2) wood-frame house with a basement and a concrete foundation weighs about 145 t (metric tonnes). But most houses are built on foundations that are excavated into the ground. This involves digging a hole and taking some material away, so we need to subtract what that excavated material weighs. Assuming our 150 m2 house required an excavation that was 15 m by 11 m by 1 m deep, that’s 165 m3 of “dirt,” which typically has a density of about 1.6 t per m3.

165 m3 of excavated soil x 1.6 t/m3 = 264 t – thus the excavated material weighs about 1.8 times as much as the house. In this case weight has been removed from the slope by building the house.