---
title: "Details of a steel window"
subject: "Building Technology"
chapter: 6
key: "semester_6/building_technology:steel-window-detail"
source: https://www.bctengineer.com/q/semester_6/building_technology/steel-window-detail
site: BCT Engineering
---

# Details of a steel window

Building Technology · Chapter 6: Doors and windows

- Asked in: 2078 Baisakh, 2 marks
- Video: [Construction Studies Scale 1:5 Section through the cill detail of a window](https://www.youtube.com/watch?v=SH1A6kdq9U4) — Michael Boyle
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_6/building_technology/steel-window-detail
- Whole chapter: https://www.bctengineer.com/md/semester_6/building_technology/chapter-6

## Question

Draw details of a steel window.

## Short answer

Steel windows use rolled Z, T or L sections (about 20×20×3 mm) welded into frames and sashes. 3 mm glass panes are fixed in rebates with steel glazing clips and putty. The frame is anchored to the wall by holdfast lugs (100 mm long) embedded at 300–450 mm spacing.

## Answer

A steel window uses rolled steel sections (Z, T or L, about 20 x 20 x 3 mm), welded to form the frame and sashes. The sash may be fixed or openable (side-hung or top-hung).

```text
 ELEVATION                       SECTION AT JAMB
 +------+-------+                  wall |  frame (Z 20x20x3)
 |      |       |                       | +--+
 |  F   |  O    |  F = fixed            | |  |= glass (3 mm)
 +------+-------+  O = openable         | +--+  putty
 |      |       |                       |  lug fixed in
 |  F   |  O    |                       |  wall 100 mm
 +------+-------+
```
Details: 3 mm glass panes are fixed in the rebates of the sections with steel glazing clips and putty; frames are fixed to the wall by 100 mm long lugs (holdfasts) embedded in 1:3 mortar, placed about 300 mm from the top and bottom and not more than 450 mm apart; handles and friction hinges are provided for the openable sash; painted with red lead primer and enamel; typical size 1.2 m x 1.2 m.

## Check yourself

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

1. What are steel windows made of?
   A. Cast iron plates
   B. Rolled steel sections (Z, T or L) welded into frames and sashes
   C. Timber with steel nails
   D. Aluminium extrusions only
   Answer: B. Rolled steel sections such as 20 x 20 x 3 mm are welded to form frames and sashes. (Key point: Steel window sections)

2. How are the 3 mm glass panes fixed?
   A. Nailed to the frame
   B. Bolted through holes
   C. In grooves with steel glazing clips and putty
   D. Held by timber beads only
   Answer: C. Glass is fixed in grooves with steel glazing clips and putty. (Key point: Fixing of glass)

3. How is the steel window frame fixed in the wall?
   A. By 100 mm lugs embedded in 1:3 mortar
   B. By welding to rebar
   C. By adhesive
   D. By timber wedges only
   Answer: A. Lugs (holdfasts) 100 mm long are embedded in 1:3 cement mortar. (Key point: Fixing frame to wall)

## Related in other subjects

- [RCC slab culvert: brick, wearing coat, GI pipe, steel](https://www.bctengineer.com/question.md?key=semester_7%2Festimating_and_costing%3Aslab-culvert-a-fig-b) — Estimating and Costing, chapter 6
- [Two-room building: excavation, PCC, brick, plaster](https://www.bctengineer.com/question.md?key=semester_7%2Festimating_and_costing%3Abuilding-h-two-room-fig1) — Estimating and Costing, chapter 6
- [Building with verandah: excavation, panelled shutter, brick](https://www.bctengineer.com/question.md?key=semester_7%2Festimating_and_costing%3Abuilding-n-fig3-three-items) — Estimating and Costing, chapter 6
- [Building: excavation, brick, paneled door, plaster](https://www.bctengineer.com/question.md?key=semester_7%2Festimating_and_costing%3Abuilding-p-four-items) — Estimating and Costing, chapter 6