---
title: "Key components of a slope roof"
subject: "Building Technology"
chapter: 4
key: "semester_6/building_technology:slope-roof-components"
source: https://www.bctengineer.com/q/semester_6/building_technology/slope-roof-components
site: BCT Engineering
---

# Key components of a slope roof

Building Technology · Chapter 4: Roofs

- Asked in: 2079 Asoj, 3 marks
- Video: [Roof Components](https://www.youtube.com/watch?v=UXkWyNcNM7g) — Buildsum
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_6/building_technology/slope-roof-components
- Whole chapter: https://www.bctengineer.com/md/semester_6/building_technology/chapter-4

## Question

Show the key components of slope roof.

## Short answer

Key components of a sloping roof are roof covering (tiles, sheets, thatch), battens/boarding, common rafters, purlins, principal rafters/trusses with tie beam, ridge piece, hip/valley rafters, wall plate, and eaves with fascia and gutter.

## Answer

A sloping (pitched) roof has the following key components:

```text
                 ridge piece
                     /\
                    /  \  <- common rafter, with battens
                   /    \     and covering on top
          purlin  o      o  purlin (on principal rafter)
                 /        \
                /__________\  <- tie beam of truss
     eaves  ___/|          |\___  eaves
                |          |
            wall plate on wall
```
1. **Roof covering** (tiles, CGI sheets, slate or thatch): keeps the rain out.
2. **Battens / boarding:** fixed over the rafters; the covering is fixed to them.
3. **Common rafters:** inclined members from the eaves to the ridge.
4. **Purlins:** horizontal members under the rafters that reduce their span.
5. **Principal rafters / trusses** and **tie beam:** carry the purlins.
6. **Ridge piece** at the top, and **hip / valley rafters** at intersections.
7. **Wall plate:** laid on the wall to spread the load.
8. **Eaves** (projecting lower edge), fascia board and gutter.

## Check yourself

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

1. What is the function of purlins in a sloping roof?
   A. Inclined members from eaves to ridge
   B. Horizontal members under rafters that reduce rafter span
   C. Spread load on top of the wall
   D. Tie the feet of the rafters
   Answer: B. Purlins run horizontally and support the rafters, reducing their span. (Key point: Purlin role)

2. What does the wall plate do?
   A. Holds the covering to rafters
   B. Forms the ridge line
   C. Spreads the roof load over the wall
   D. Drains rainwater
   Answer: C. The wall plate sits on the wall top and distributes the load from rafters. (Key point: Wall plate)

3. What are battens fixed on rafters used for?
   A. To fix the roof covering
   B. To carry the trusses
   C. To tie the walls together
   D. To collect rainwater
   Answer: A. Battens or boarding over rafters hold the covering. (Key point: Battens)

## Related in Building Technology

- [Timber collar beam roof and roof coverings](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Acollar-beam-roof-coverings) — Building Technology, chapter 4
- [Four types of single roof](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Asingle-roof-four-types) — Building Technology, chapter 4
- [Flat roof versus pitched roof](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Aflat-vs-pitched) — Building Technology, chapter 4, asked 2×
- [Requirements of good roof; pitched roof types](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Aroof-requirements-pitch-066j) — Building Technology, chapter 4

## Related in other subjects

- [Key components of electric traction system](https://www.bctengineer.com/question.md?key=semester_7%2Futilization_of_electrical_energy%3Acomponents-electric-traction-system) — Utilization of Electrical Energy, chapter 4
- [Cross drainage: Q 50, HFD 450, uplift on roof](https://www.bctengineer.com/question.md?key=semester_6%2Firrigation_and_drainage_engineering%3Acd-q50-fsd15-hfd450-uplift-roof) — Irrigation and Drainage Engineering, chapter 8, asked 2×
- [Cross drainage: Q 25, uplift on roof of barrel](https://www.bctengineer.com/question.md?key=semester_6%2Firrigation_and_drainage_engineering%3Acd-q25-uplift-roof-barrel-800) — Irrigation and Drainage Engineering, chapter 8, asked 2×
- [Wind pressure on pitched roof on hill](https://www.bctengineer.com/question.md?key=semester_6%2Fdesign_of_steel_and_timber_structure%3Awind-pitched-roof-eaves-10m) — Design of Steel and Timber Structure, chapter 8