---
title: "Purpose and sizing of doors and windows; panelled doors"
subject: "Building Technology"
chapter: 6
key: "semester_6/building_technology:door-window-purpose-sizing"
source: https://www.bctengineer.com/q/semester_6/building_technology/door-window-purpose-sizing
site: BCT Engineering
---

# Purpose and sizing of doors and windows; panelled doors

Building Technology · Chapter 6: Doors and windows

- Asked in: 2073 Bhadra
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_6/building_technology/door-window-purpose-sizing
- Whole chapter: https://www.bctengineer.com/md/semester_6/building_technology/chapter-6

## Question

Discuss purpose and sizing of doors and windows. List different terms used in panelled doors.

## Short answer

Doors provide access, privacy, security, and protection; windows admit daylight, air, view, and enhance appearance. Sizing: main entrance 1.0-1.2m x 2.1m, room doors 0.9m x 2.0-2.1m, bathroom doors 0.6-0.75m x 2.0m, windows 0.9-1.5m wide with sill 0.75-0.9m high, window area 10-20% of floor area. Panelled door terms: frame, shutter, styles, rails, panels, muntin, transom, mullion, horn, mortise-tenon joints, hinges, lock, handle.

## Answer

#### Purpose of doors and windows
- **Doors:** give access to rooms and the building, and provide privacy, security and protection from weather, noise and fire.
- **Windows:** admit daylight and fresh air, give a view and ventilation, and add to the appearance.

#### Sizing (as per NBC and usual practice)
| Item | Usual size |
|---|---|
| Main entrance door | 1.0-1.2 m wide, 2.1 m high |
| Room doors | 0.9 m wide, 2.0-2.1 m high |
| Bathroom / WC doors | 0.6-0.75 m wide, 2.0 m high |
| Fire exits / hospital doors | 1.2 m wide or more |
| Windows | Width 0.9-1.5 m, sill 0.75-0.9 m above floor |
| Window area | 10-20% of floor area (at least 10%); ventilators 5% |

The door height should give a head clearance of at least 2.0 m, and the opening should allow furniture to pass.

#### Terms used in panelled doors
- **Frame (chaukhat):** head and two jambs.
- **Shutter:** the moving leaf.
- **Styles:** vertical outer members; **rails:** top, frieze, lock and bottom rails.
- **Panels:** infilling boards of timber/plywood/glass.
- **Muntin:** intermediate vertical member between panels.
- **Transom:** horizontal frame member separating the door from a fanlight above; **mullion:** vertical frame member dividing the opening.
- **Horn:** projection of the frame head into the wall.
- **Mortise and tenon joints** between styles and rails.
- **Hinges, lock and handle.**

## Check yourself

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

1. What window area relative to floor area is usual?
   A. 10-20% (at least 10%)
   B. 1-2%
   C. 40-50%
   D. At least 30%
   Answer: A. The sizing table gives 10-20% of floor area, minimum 10%. (Key point: Window area)

2. What is the usual width of a room door?
   A. 0.6 m
   B. 0.9 m
   C. 1.5 m
   D. 2.1 m
   Answer: B. Room doors are 0.9 m wide; bathroom doors are 0.6-0.75 m. (Key point: Room door size)

3. Which door is narrowest?
   A. Main entrance, 1.0-1.2 m
   B. Fire exit, 1.2 m
   C. Bathroom/WC door, 0.6-0.75 m
   D. Room door, 0.9 m
   Answer: C. Bathroom and WC doors are the narrowest. (Key point: Bathroom door)

4. What is the horn in a panelled door frame?
   A. The vertical divider between panels
   B. The wider middle rail
   C. The sloping sill of the window
   D. Projection of the frame into the wall
   Answer: D. Horns are frame projections built into masonry. (Key point: Horn)

## Related in Building Technology

- [Elements of panelled and battened doors](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Apanelled-battened-elements) — Building Technology, chapter 6
- [Thermal insulation of walls, doors, windows, roofs](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Athermal-insulation-exposed-walls) — Building Technology, chapter 1, asked 3×
- [General parts of doors and windows](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Adoor-window-parts) — Building Technology, chapter 6, asked 2×
- [Terms used in a pitched roof](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Aroof-terminology) — Building Technology, chapter 4, asked 4×
- [Casement, louvered and corner windows](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Acasement-louvered-corner) — Building Technology, chapter 6

## Related in other subjects

- [Multiplying factors for painting doors](https://www.bctengineer.com/question.md?key=semester_7%2Festimating_and_costing%3Amultiplying-factors-painting-doors) — Estimating and Costing, chapter 2
- [Types and purpose of admixtures](https://www.bctengineer.com/question.md?key=semester_5%2Fconcrete_technology_and_masonry_structure%3Aadmixture-types-purpose) — Concrete Technology and Masonry Structure, chapter 1, asked 7×
- [Types of unit weights in phase terms](https://www.bctengineer.com/question.md?key=semester_4%2Fsoil_mechanics%3Aunit-weights-phase-relations) — Soil Mechanics, chapter 2
- [Manning's equation, terms and slope S](https://www.bctengineer.com/question.md?key=semester_4%2Fhydraulics%3Amannings-equation-terms-and-slope) — Hydraulics, chapter 6