---
title: "Damp proofing and defects due to moisture"
subject: "Building Technology"
chapter: 1
key: "semester_6/building_technology:damp-proofing-defects"
source: https://www.bctengineer.com/q/semester_6/building_technology/damp-proofing-defects
site: BCT Engineering
---

# Damp proofing and defects due to moisture

Building Technology · Chapter 1: Functional Requirements of Buildings

- Asked in: 2070 Magh
- Video: [how to protect Building building against Dampness?|Damp Proofing Materials| Damp Proofing Remedies](https://www.youtube.com/watch?v=2xjMbJoR-N4) — Civillogy (Study of Civil Engineering)
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_6/building_technology/damp-proofing-defects
- Whole chapter: https://www.bctengineer.com/md/semester_6/building_technology/chapter-1

## Question

What do you understand by Damp proofing in building? Illustrate the defects in building due to moisture.

## Short answer

Damp proofing uses impervious layers like DPC, integral compounds, surface treatments, cavity walls, and drainage to stop moisture. Defects from moisture are stains, efflorescence, disintegration of masonry, timber decay, corrosion of steel, mould growth, reduced strength, damage to floors and furniture, electrical short circuits, and cracks.

## Answer

**Damp proofing** is the treatment of a building, by providing an impervious layer (DPC) or other measures, to prevent moisture from the ground, rain or other sources from entering the walls, floors and roofs.

Methods in brief: membrane DPC (bitumen felt, polythene, cement concrete 1:2:4 with waterproofing compound at plinth level), integral waterproofing compounds, surface treatments (waterproof plaster and paint), cavity walls, guard drains, and grouting or injection in old buildings.

#### Defects in buildings due to moisture (dampness)
1. **Stains and patches** on walls and ceilings; peeling or blistering of paint, plaster and wallpaper.
2. **Efflorescence**: White crystals of salts brought to the surface, spoiling the appearance and breaking plaster.
3. **Disintegration of bricks, stone and mortar**; softening of plaster.
4. **Decay and rot of timber** (doors, windows, floors) and termite attack.
5. **Corrosion of steel** and reinforcement, causing concrete to crack and spall.
6. **Growth of fungus, moss and mould**, giving a bad smell and unhealthy conditions.
7. **Reduced strength and thermal insulation** of walls.
8. **Damage to floor coverings and furniture**; warping of timber floors.
9. **Electrical short circuits**.
10. **Cracks** and uplift of flooring due to swelling.
11. **Lower property value** and uncomfortable living.

## Check yourself

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

1. What is damp proofing?
   A. Making a building fireproof
   B. Removing salts from bricks only
   C. Painting walls for appearance
   D. Preventing moisture from entering walls, floors and roofs using a DPC or other measures
   Answer: D. Damp proofing treats the building with an impervious layer or other measures to keep moisture out. (Key point: Damp proofing)

2. What is efflorescence?
   A. Rust on steel bars
   B. Growth of moss on timber
   C. Swelling of floors
   D. White salt crystals brought to the wall surface
   Answer: D. Salts carried by moisture crystallise on the surface, spoiling appearance. (Key point: Efflorescence)

3. What happens to reinforcement in damp buildings?
   A. It becomes stronger
   B. It stays unaffected
   C. It corrodes, cracking and spalling the concrete
   D. It shrinks and leaves the concrete
   Answer: C. Corrosion expands the steel, causing cracks and spalling of the concrete. (Key point: Steel corrosion)

4. Which cement concrete mix is used for a plinth DPC with waterproofing compound?
   A. 1:3:6
   B. 1:2:4
   C. 1:6
   D. 1:8
   Answer: B. A 1:2:4 concrete with compound is used as DPC at plinth. (Key point: DPC concrete mix)

## Related in Building Technology

- [Methods of damp proofing](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Adamp-proofing-methods) — Building Technology, chapter 1, asked 2×
- [Damp-proofing versus water-proofing](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Adamp-vs-waterproofing) — Building Technology, chapter 1
- [Moisture movement through building components](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Amoisture-movement) — Building Technology, chapter 1, asked 7×
- [Below and above grade water proofing](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Awaterproof-below-above-grade) — Building Technology, chapter 1
- [Audible sound, reflected-sound defects, insulation](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Asound-audible-insulation) — Building Technology, chapter 1
- [Positive and negative side water proofing](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Awaterproof-positive-negative) — Building Technology, chapter 1

## Related in other subjects

- [Defects caused by seasoning](https://www.bctengineer.com/question.md?key=semester_3%2Fcivil_engineering_materials%3Aseasoning-defects-timber) — Civil Engineering Materials, chapter 7
- [Defects of timber by natural forces](https://www.bctengineer.com/question.md?key=semester_3%2Fcivil_engineering_materials%3Atimber-defects-natural-forces) — Civil Engineering Materials, chapter 7
- [Frequency of irrigation from soil moisture](https://www.bctengineer.com/question.md?key=semester_6%2Firrigation_and_drainage_engineering%3Afrequency-of-irrigation-soil-moisture) — Irrigation and Drainage Engineering, chapter 2