Which situation requires underpinning?

The foundation has settled or is weak due to poor soil or overload

Why may underpinning be needed when extra storeys are added?

Because loads on the foundation increase

Because the water table drops permanently

Because the wall becomes thinner

How can a neighbouring deep excavation or basement create a need for underpinning?

It lowers the support around the existing foundation

It increases the bearing capacity

2072 Magh · 2 marks

Necessity of underpinning work

Short answer

Underpinning is necessary when foundations have settled or are weak due to poor soil or overload, when loads increase (e.g. extra storeys), when adjacent deep excavation or lowered water table reduces bearing capacity, or when the original foundation is faulty or damaged by roots, mining, subsidence or earthquake.

Describe the necessity of underpinning work.

Underpinning is needed in the following cases.

Foundation has settled or is weak due to poor soil or an overload.
A building is to be raised (extra storeys) and loads increase.
Adjacent deep excavation or new basement lowers the support (e.g. neighbouring building).
A change in water table, scouring or earthquake damage reduces bearing capacity.
Faulty or shallow original foundation, or damage by roots, mining, or subsidence.

✓ Answer checked by Claude Opus 5.5 (high effort)

Underpinning: necessity, procedure, methods · Building Technology, chapter 8 · asked 3×
Scaffolding, underpinning, shoring; underpinning methods · Building Technology, chapter 8

All Building Technology chapter 8 questions →

Necessity of underpinning work

Related questions