---
title: "Common problems of existing foundations"
subject: "Building Technology"
chapter: 2
key: "semester_6/building_technology:problems-existing-foundation"
source: https://www.bctengineer.com/q/semester_6/building_technology/problems-existing-foundation
site: BCT Engineering
---

# Common problems of existing foundations

Building Technology · Chapter 2: Foundations

- Asked in: 2078 Chaitra, 3 marks; 2070 Bhadra, 8 marks (asked 2 times)
- Video: [16 Tips --Watch BEFORE House Foundation Repairs](https://www.youtube.com/watch?v=oW4j9bP6ULQ) — Overanalytical DIY
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_6/building_technology/problems-existing-foundation
- Whole chapter: https://www.bctengineer.com/md/semester_6/building_technology/chapter-2

## Question

Discuss the common problems with existing foundation.

## Short answer

Common problems include differential settlement causing cracks and tilting, dampness from failed DPC, material deterioration from sulphate attack and corrosion, soil movement like swelling and shrinkage, overloading from added storeys, damage from adjacent excavation or vibration, and earthquake-induced failure.

## Answer

Existing foundations commonly suffer from the following problems.

1. **Settlement**: Uniform or differential settlement from consolidation of soil, weak strata, heavy loads or extra floors added; it causes cracks in walls and floors, tilting, and door and window jamming.
2. **Cracks** in the foundation, plinth and walls from settlement, soil movement or earthquake.
3. **Dampness**: Capillary rise because DPC has failed or was never provided; water table rise, leaking drains.
4. **Deterioration of materials**: Sulphate attack on concrete, corrosion of reinforcement, rotting of timber, and weathering of stone and brick.
5. **Soil movement**: Swelling and shrinking of expansive soil, erosion of soil from the base, scour near rivers and drains.
6. **Overloading** due to change of use or vertical extension without checking capacity.
7. **Effect of nearby work**: Excavation, construction of neighbouring building, pile driving, vibration, blasting.
8. **Tree roots and water table lowering** causing shrinkage settlement.
9. **Landslide or slope failure** on hill sites.
10. **Earthquake damage** and liquefaction.

#### Remedies
Underpinning (pit method, pile method), enlarging the footing, grouting, soil stabilisation, drainage improvement, repair of cracks and DPC, chemical injection, and strengthening by jacketing.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. What does settlement of an existing foundation cause?
   A. Increased strength
   B. Only paint fading
   C. Higher DPC level
   D. Wall cracks, tilting and jamming of doors and windows
   Answer: D. Settlement shows as cracks, tilting and jammed openings. (Key point: Settlement effects)

2. What causes dampness in existing foundations?
   A. Capillary rise where the DPC failed or was never provided
   B. Too thick DPC
   C. Dry soil
   D. Lowered ground water
   Answer: A. A failed or missing DPC lets capillary water rise. (Key point: Dampness)

3. Why is adding floors without checks a problem?
   A. It lowers the water table
   B. It overloads the foundation beyond its capacity
   C. It strengthens the soil
   D. It improves DPC
   Answer: B. Vertical extension increases load beyond the original capacity. (Key point: Overloading)

4. Which is a remedy for settled foundations?
   A. Painting
   B. Adding plaster
   C. Lowering the roof slope
   D. Underpinning
   Answer: D. Underpinning (pit or pile method) strengthens the foundation. (Key point: Remedy)

## Related in Building Technology

- [Foundation classification and problems](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Afoundation-class-problems) — Building Technology, chapter 2, asked 2×
- [Deep foundation types and use of shallow foundations](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Adeep-shallow-types-079a) — Building Technology, chapter 2
- [Foundations on black cotton soil](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Ablack-cotton-foundation) — Building Technology, chapter 2
- [When pile and mat foundations are chosen](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Apile-mat-scenarios) — Building Technology, chapter 2
- [Causes of foundation failure](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Afoundation-failures) — Building Technology, chapter 2, asked 2×
- [Situations demanding pile foundation](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Apile-situations) — Building Technology, chapter 2, asked 2×

## Related in other subjects

- [Why foundations; types of foundation](https://www.bctengineer.com/question.md?key=semester_5%2Ffoundation_engineering%3Awhy-foundations-types) — Foundation Engineering, chapter 1
- [Case study: new system vs existing (cost, manpower)](https://www.bctengineer.com/question.md?key=semester_5%2Finstrumentation_ii%3Acs-cost-manpower-automation) — Instrumentation II, chapter 10, asked 4×
- [Classify shallow and deep foundations](https://www.bctengineer.com/question.md?key=semester_5%2Ffoundation_engineering%3Aclassify-foundations-soil) — Foundation Engineering, chapter 1, asked 4×
- [Classification of pile foundations](https://www.bctengineer.com/question.md?key=semester_5%2Ffoundation_engineering%3Apile-classification-material-load) — Foundation Engineering, chapter 8