---
title: "Rubble, coursed rubble and ashlar masonry"
subject: "Building Technology"
chapter: 3
key: "semester_6/building_technology:rubble-coursed-ashlar"
source: https://www.bctengineer.com/q/semester_6/building_technology/rubble-coursed-ashlar
site: BCT Engineering
---

# Rubble, coursed rubble and ashlar masonry

Building Technology · Chapter 3: Mortars & Masonry works

- Asked in: 2076 Bhadra, 4 marks; 2069 Bhadra, 4 marks (asked 2 times)
- Video: [Type of stone masonry/Rubble masonry/Ashlar masonry](https://www.youtube.com/watch?v=0gepAvupilo) — MFA 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/rubble-coursed-ashlar
- Whole chapter: https://www.bctengineer.com/md/semester_6/building_technology/chapter-3

## Question

Describe random rubble, coursed rubble and ashlar stone masonry with sketches.

## Short answer

Random rubble uses irregular stones without courses, with bond stones every 1.5 m². Coursed rubble lays roughly dressed stones in courses of equal height. Ashlar masonry uses finely dressed rectangular blocks with thin joints (3–6 mm) in regular courses.

## Answer

#### Random rubble masonry
Stones of irregular shape and size, as obtained from the quarry, are laid without courses; small stones fill the gaps.
- **Uncoursed random rubble:** stones used as they come, roughly shaped with a hammer; bond stones (through stones) every 1.5 m² of wall.
- **Coursed random rubble:** work is levelled at about every 300-350 mm height to form rough courses.
- Joints are irregular, mortar 1:6 (cement-sand) or mud/lime mortar; thickness of wall at least 400 mm.
- Cheap, suitable for foundations, boundary and retaining walls in hilly areas of Nepal.

```text
   ____ ___ _____ __
  /    \   \     \  \   irregular stones,
 /__ ___\___\_____\__\  no regular courses
 \  /   /  / \    /
  \/___/__/___\__/
```

#### Coursed rubble masonry
Stones are roughly dressed and laid in courses of equal height in each course; height of courses may differ from course to course.
- **First sort:** face stones squared with hammer, courses 150-300 mm high, joints thin (about 10 mm); all courses levelled.
- **Second sort:** stones roughly dressed, joints thicker; courses not so regular.
- **Third sort:** stones hammer-dressed lightly, used for ordinary walls.
- Bond stones 1 per m² of face and quoin stones at corners; stronger and neater than random rubble.

```text
 +------+---+-----+--+   course 1 (h1)
 +--+-------+----+---+   course 2 (h2)
 +-----+-----+--+-----+   course 3 (h3)
```

#### Ashlar masonry
Stones are finely dressed to exact rectangular blocks with fine joints (3-6 mm) and laid in regular courses; it is the best and costliest stone masonry.
- **Ashlar fine:** every face chisel-dressed, joints 3 mm; used for monumental buildings.
- **Ashlar rough-tooled:** faces roughly tooled, joints up to 6 mm.
- **Ashlar rock-faced (quarry-faced):** face left rough with a dressed margin around.
- **Ashlar chamfered:** edges chamfered at 45 degrees, giving a V-joint.
- **Block-in-course:** blocks of equal height dressed; backing of rubble.

```text
 +------+------+------+
 +---+------+------+--+   regular courses,
 +------+------+------+   thin joints
```

## Check yourself

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

1. Uncoursed random rubble:
   A. Is dressed fine
   B. Is laid without regular courses using irregular quarry stones
   C. Uses thin joints
   D. Is in equal courses
   Answer: B. Cheap, for foundations and boundary walls. (Key point: Random rubble)

2. In coursed rubble, courses are:
   A. Random
   B. Always equal across all
   C. Equal height within each course, may differ between courses
   D. Absent
   Answer: C. Stones are hammer-dressed and laid in levelled courses. (Key point: Coursed rubble)

3. Ashlar fine masonry has joints of about:
   A. 100 mm
   B. 3 mm
   C. 50 mm
   D. 25 mm
   Answer: B. Every face is chisel-dressed with thin joints. (Key point: Ashlar fine)

## Related in Building Technology

- [Random rubble and dry rubble masonry](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Arandom-dry-rubble) — Building Technology, chapter 3
- [Types of stone masonry](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Astone-masonry-types) — Building Technology, chapter 3, asked 5×

## Related in other subjects

- [Detailed specification of stone masonry in 1:6 mortar](https://www.bctengineer.com/question.md?key=semester_8%2Fconstruction_management%3Adetailed-spec-stone-masonry-1-6) — Construction Management, chapter 12
- [Materials for 5 m³ stone masonry 1:6](https://www.bctengineer.com/question.md?key=semester_7%2Festimating_and_costing%3Amaterials-stone-masonry-5m3) — Estimating and Costing, chapter 4
- [Types of stone masonry and characteristics](https://www.bctengineer.com/question.md?key=semester_5%2Fdesign_of_timber_and_masonry_structures%3Astone-masonry-types-characteristics) — Design of Timber and Masonry Structures, chapter 4