---
title: "Causes and remedies of cracks"
subject: "Building Technology"
chapter: 10
key: "semester_6/building_technology:cracks-causes-remedial"
source: https://www.bctengineer.com/q/semester_6/building_technology/cracks-causes-remedial
site: BCT Engineering
---

# Causes and remedies of cracks

Building Technology · Chapter 10: Causes and prevention of cracks in buildings

- Asked in: 2078 Chaitra, 4 marks; 2077 Chaitra, 4 marks (asked 2 times)
- Video: [Why Has Your Wall Cracked? and What Can You Do?](https://www.youtube.com/watch?v=Fpdb69ccNkI) — Skill Builder
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_6/building_technology/cracks-causes-remedial
- Whole chapter: https://www.bctengineer.com/md/semester_6/building_technology/chapter-10

## Question

Write down the causes of cracks that occur in a building and its remedial measures briefly.

## Short answer

Causes: moisture and thermal movement, foundation settlement, elastic deformation, reinforcement corrosion, chemical attack, vegetation, earthquake, poor work, overloading, fire. Remedial measures: hairline – cement slurry; small – rake and fill with 1:3 mortar; medium – epoxy injection; wide – stitching, jacketing or rebuild; settlement – underpinning; provide movement joints and good curing.

## Answer

Cracks in buildings arise from the following causes.

| Cause | How it cracks the building |
|---|---|
| **Moisture movement** | Bricks, blocks and concrete expand on wetting and shrink on drying; mortar and plaster shrinkage |
| **Thermal movement** | Expansion and contraction with temperature in roofs, long walls, parapets |
| **Settlement of foundation** | Unequal settlement due to poor or non-uniform soil, wrong foundation level, change in moisture, or inadequate depth |
| **Elastic deformation** | Overload, deflection of beams and slabs, bending and shear |
| **Corrosion of reinforcement** | Rust expands and splits the concrete cover |
| **Chemical action** | Sulphate attack, alkali-aggregate reaction, carbonation |
| **Vegetation** | Roots of trees near walls and foundations |
| **Earthquake and wind** | Lateral forces on weak walls and joints |
| **Poor workmanship and materials** | Poor curing, mix, bonding, early removal of formwork, missing joints |
| **Overloading and design error** | Excess load, wrong detailing |
| **Fire, vibration** | Heat damage, machine vibration |

#### Remedial measures
| Crack width | Remedy |
|---|---|
| Hairline (< 0.3 mm) | Fill with cement slurry or paint-grade filler; fresh plaster |
| Small (0.3-1.0 mm) | Rake out, fill with cement-sand mortar (1:3) or polymer-modified mortar |
| Medium (1-3 mm) | Epoxy injection or cement grout through packers |
| Wide (> 3 mm) | Remove and rebuild, stitching with steel clamps, epoxy mortar, jacketing |
| Foundation settlement | Underpinning, grouting, soil improvement |
| RCC cracks | Epoxy injection, grouting, jacketing, bonding steel plates |
| Roof cracks | Waterproof treatment, expansion joints, sealants |

Additional measures: provide movement joints, good drainage, proper curing, tie beams, and good-quality materials.

## Check yourself

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

1. Thermal movement mainly cracks:
   A. Roofs, long walls and parapets
   B. Buried footings only
   C. Interior partitions only
   D. Doors
   Answer: A. Expansion and contraction act most on exposed roofs, long walls and parapets. (Key point: Thermal movement)

2. Cracks from foundation settlement are remedied by:
   A. Cement slurry
   B. Underpinning, grouting or soil improvement
   C. Paint
   D. Fresh plaster only
   Answer: B. The foundation itself must be strengthened. (Key point: Remedy for foundation settlement)

3. A hairline crack (< 0.3 mm) is treated by:
   A. Epoxy injection
   B. Jacketing
   C. Cement slurry or filler and fresh plaster
   D. Rebuilding
   Answer: C. Surface filling is enough for hairline cracks. (Key point: Remedy by width)

## Related in Building Technology

- [Painting on masonry; causes and remedies of cracks](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Apainting-masonry-cracks) — Building Technology, chapter 9
- [Causes of cracks in a building](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Acauses-of-cracks) — Building Technology, chapter 10, asked 3×
- [Structural vs non-structural cracks and causes](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Acracks-struct-nonstruct-causes) — Building Technology, chapter 10
- [Methods of repairing cracks](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Acrack-repair-methods) — Building Technology, chapter 10, asked 3×
- [Acoustics, acoustic defects and remedies](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Aacoustics-defects-remedial) — Building Technology, chapter 1
- [Structural and non-structural cracks](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Acracks-structural-nonstructural) — Building Technology, chapter 10, asked 4×

## Related in other subjects

- [Water logging: causes, effects, remedies](https://www.bctengineer.com/question.md?key=semester_6%2Firrigation_and_drainage_engineering%3Awater-logging-causes-effects-remedies) — Irrigation and Drainage Engineering, chapter 9, asked 13×
- [Remedial measures for slope failure](https://www.bctengineer.com/question.md?key=semester_4%2Fsoil_mechanics%3Aslope-remedial-measures) — Soil Mechanics, chapter 11
- [In-plane, out-of-plane failure and remedial measures](https://www.bctengineer.com/question.md?key=semester_5%2Fconcrete_technology_and_masonry_structure%3Ain-plane-out-of-plane-remedial) — Concrete Technology and Masonry Structure, chapter 9
- [Remedial measures for sediment deposition in RoR](https://www.bctengineer.com/question.md?key=semester_7%2Fhydropower_engineering%3Aror-sediment-deposition-remedial-measures) — Hydropower Engineering, chapter 5