---
title: "Stay bracing and vertical sheeting"
subject: "Building Technology"
chapter: 8
key: "semester_6/building_technology:stay-bracing-sheeting"
source: https://www.bctengineer.com/q/semester_6/building_technology/stay-bracing-sheeting
site: BCT Engineering
---

# Stay bracing and vertical sheeting

Building Technology · Chapter 8: Temporary construction

- Asked in: 2076 Baisakh, 6 marks
- Video: [Timbering and Strutting (Foundation)](https://www.youtube.com/watch?v=kytkdTNtWPA) — Diploma Classes
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_6/building_technology/stay-bracing-sheeting
- Whole chapter: https://www.bctengineer.com/md/semester_6/building_technology/chapter-8

## Question

Describe stay bracing and vertical sheeting.

## Short answer

Stay bracing uses spaced vertical poling boards with horizontal struts for firm soil up to 2 m depth. Vertical sheeting uses continuous vertical boards touching each other, held by walings and struts, for loose soil up to 3 m or more. Sheeting provides full-face support unlike the gaps in stay bracing.

## Answer

Both are methods of timbering trenches to hold the sides of the excavation.

#### Stay bracing
Used in fairly firm soil for depths up to about 2 m. Vertical boards (**poling boards**, 200 x 40 mm) are placed at 2-3 m centres on opposite faces of the trench and kept apart by horizontal **struts** (props). The poling boards are placed at intervals, leaving the soil between exposed. The struts are fixed at 1.2-1.5 m centres vertically, and can be wedged.

```text
   |board   strut   board|
   |  |==========|  |
   |  |          |  |
   |  |==========|  |   (soil between boards
   |__|__________|__|    left unsupported)
```

#### Vertical sheeting
Used in loose soil and for depths up to 3 m (or more). Vertical boards (**sheeting**), 25-40 mm thick, are placed side by side touching each other, so the whole face is covered. They are held by horizontal **walings** (120 x 120 mm) on the inside, with struts across the trench at about 1.2-1.5 m c/c.

```text
   |sheet|waling|  strut  |waling|sheet|
   ||||||=====o===========o=====||||||
   ||||||                      ||||||
   ||||||=====o===========o=====||||||
```
**Difference:** stay bracing leaves gaps between boards, while vertical sheeting gives continuous support. Sheeting is thus used for looser soil.

## Check yourself

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

1. In stay bracing, the soil between poling boards is:
   A. Fully covered
   B. Left exposed
   C. Replaced by concrete
   D. Frozen
   Answer: B. Poling boards are placed at intervals leaving soil between exposed. (Key point: Stay bracing)

2. Vertical sheeting is held by:
   A. Wedges only
   B. Rakers
   C. Needles
   D. Horizontal walings on the inside with struts across the trench
   Answer: D. Sheeting boards touch each other and are held by walings and struts. (Key point: Vertical sheeting)

3. The main difference between the two is that:
   A. They are identical
   B. Stay bracing is for looser soil
   C. Stay bracing leaves gaps; vertical sheeting gives continuous support for looser soil
   D. Sheeting is used only in rock
   Answer: C. Continuous support in sheeting suits looser soil. (Key point: Difference)

## Related in other subjects

- [Truss: force method, EA and 2EA members](https://www.bctengineer.com/question.md?key=semester_5%2Ftheory_of_structures_ii%3Atruss-force-method-ea-2ea-50kn) — Theory of Structures II, chapter 2