---
title: "English and rat-trap bonds"
subject: "Concrete Technology and Masonry Structure"
chapter: 7
key: "semester_5/concrete_technology_and_masonry_structure:english-rat-trap-bond"
source: https://www.bctengineer.com/q/semester_5/concrete_technology_and_masonry_structure/english-rat-trap-bond
site: BCT Engineering
---

# English and rat-trap bonds

Concrete Technology and Masonry Structure · Chapter 7: Introduction to masonry structures

- Asked in: 2080 Bhadra, 4 marks
- Video: [One of Most Effective Bond | Rat Trap Bond | Low Cost Bond | Low Cost construction](https://www.youtube.com/watch?v=TcKa6bAoH_U) — The Institute of Construction Managment 
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_5/concrete_technology_and_masonry_structure/english-rat-trap-bond
- Whole chapter: https://www.bctengineer.com/md/semester_5/concrete_technology_and_masonry_structure/chapter-7

## Question

Explain English and rat-trap bonds with neat sketches.

## Short answer

English bond alternates stretcher and header courses with a queen closer beside the quoin header to stagger joints; it is the strongest bond. Rat-trap bond lays bricks on edge, forming a hollow cavity; stretchers form both faces and headers tie the wall, leaving a 110–120 mm cavity that saves about 25% bricks.

## Answer

#### English bond

Alternate courses of **stretchers** and **headers**. A queen closer is placed next to the quoin header in each header course so that the vertical joints stay staggered. It gives a strong transverse and longitudinal bond and is the most common bond for load-bearing walls one brick thick or more.

```text
Elevation (1 brick wall)       Plan, course 1 / course 2
 ________ ________ ______     course 1 (stretcher)
|________|________|______|    |==========|==========|
|__|__ _|_ _ _|_ _ _|_ __|    course 2 (header)
|________|________|______|    |==|==|==|==|==|==|==|==|
|__|__ _|_ _ _|_ _ _|_ __|
```

#### Rat-trap bond

Bricks are laid **on edge** (rowlock) so that a hollow cavity is formed inside the wall. Stretchers on edge form the two faces and headers on edge tie them together at intervals. Each face stretcher takes up only about 55 mm of the wall thickness, so a cavity about 110 to 120 mm wide (roughly one brick width) remains. The wall is usually 230 mm thick (brick $230\times110\times55$ mm or similar), and the cavity gives the bond its name, "rat trap".

```text
Plan of alternate courses (wall thickness t)
Course 1:  |#####|     |#####|     |#####|   <- header on edge
           |#######################|
           |#######################|  face stretchers on edge
Course 2:  |#######################|
           |   cavity (hollow)     |
           |#######################|
```

Features: about 25 percent saving in bricks and 10 to 15 percent saving in mortar and cost, good thermal insulation and a lighter wall. The cavity may be filled with lean concrete or insulating material.

## Check yourself

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

1. Why is a queen closer placed beside the quoin header in English bond?
   A. To make the wall hollow
   B. To save bricks
   C. To keep the vertical joints staggered
   D. To increase thickness
   Answer: C. The queen closer maintains the lap between courses. (Key point: English bond closer)

2. How are bricks laid in rat-trap bond?
   A. On edge, leaving a hollow cavity inside the wall
   B. Flat, in solid courses
   C. At 45°
   D. As all stretchers on end
   Answer: A. Edge-laid stretchers on faces and headers across form a cavity. (Key point: Rat-trap placement)

3. What savings does rat-trap bond give?
   A. About 5% bricks only
   B. About 25% bricks and 10 to 15% mortar and cost
   C. About 60% bricks
   D. No saving
   Answer: B. The cavity reduces the number of bricks and amount of mortar. (Key point: Rat-trap savings)

4. How wide is the cavity in rat-trap bond?
   A. Equal to the wall thickness
   B. Equal to 345 mm
   C. No cavity exists
   D. Equal to the brick thickness in a 230 mm wall
   Answer: D. The bricks on edge leave a cavity equal to the brick thickness. (Key point: Cavity width)

## Related in Concrete Technology and Masonry Structure

- [Brick bond types; rat-trap bond merits and demerits](https://www.bctengineer.com/question.md?key=semester_5%2Fconcrete_technology_and_masonry_structure%3Abond-types-rat-trap-pros-cons) — Concrete Technology and Masonry Structure, chapter 7
- [Rat-trap bond and its advantages](https://www.bctengineer.com/question.md?key=semester_5%2Fconcrete_technology_and_masonry_structure%3Arat-trap-bond-advantages) — Concrete Technology and Masonry Structure, chapter 7
- [Reinforced and unreinforced masonry; rat-trap bond](https://www.bctengineer.com/question.md?key=semester_5%2Fconcrete_technology_and_masonry_structure%3Areinforced-unreinforced-rat-trap) — Concrete Technology and Masonry Structure, chapter 7
- [English and Flemish bond](https://www.bctengineer.com/question.md?key=semester_5%2Fconcrete_technology_and_masonry_structure%3Aenglish-flemish-bond) — Concrete Technology and Masonry Structure, chapter 7, asked 2×
- [Use of masonry; English and Flemish bond](https://www.bctengineer.com/question.md?key=semester_5%2Fconcrete_technology_and_masonry_structure%3Amasonry-use-english-flemish) — Concrete Technology and Masonry Structure, chapter 7