---
title: "Suspended ground floor; tile flooring"
subject: "Building Technology"
chapter: 7
key: "semester_6/building_technology:suspended-ground-floor-tile"
source: https://www.bctengineer.com/q/semester_6/building_technology/suspended-ground-floor-tile
site: BCT Engineering
---

# Suspended ground floor; tile flooring

Building Technology · Chapter 7: Flooring

- Asked in: 2080 Chaitra, 1+4 marks
- Video: [Building an Extension #3 - Suspended Beam & Block Floor](https://www.youtube.com/watch?v=N-9RbjZj7-o) — Skill Builder
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_6/building_technology/suspended-ground-floor-tile
- Whole chapter: https://www.bctengineer.com/md/semester_6/building_technology/chapter-7

## Question

What is the purpose of providing suspended ground floor? Explain the construction process of tile flooring.

## Short answer

A suspended ground floor is raised above ground to prevent dampness, ventilate timber, and provide warmth. Tile flooring is constructed by cleaning base, spreading 20-25 mm mortar bed (1:4), applying slurry, laying soaked tiles with spacers, grouting after 24-48 hours, and curing 3-7 days.

## Answer

#### Purpose of a suspended ground floor
A suspended ground floor is raised above the ground with a ventilated void beneath. It is provided to stop dampness rising into the floor, to ventilate the timber and prevent dry rot, and to give a warm floor surface. It is used on damp sites, sites with a high water table, and sloping ground.

#### Construction of tile flooring
1. **Base preparation:** the RCC slab or concrete sub-floor is cleaned of dust and mortar and wetted. A level line is marked on the walls.
2. **Mortar bed:** a 20-25 mm bed of cement-sand mortar (1:4) is spread, stiff and level, to the required slope.
3. **Slurry coat:** a thin layer of neat cement slurry (or adhesive) is spread over the bed.
4. **Laying tiles:** the tiles are soaked (for ceramic), then laid from the centre or a corner. Each is pressed and tapped with a rubber mallet, checking line and level with a straight edge and spirit level. Spacers keep the joints at 2-3 mm.
5. **Grouting:** after 24-48 hours the joints are cleaned and filled with cement or coloured grout. The excess is wiped off with a damp cloth.
6. **Curing and cleaning:** the floor is cured for 3-7 days, then cleaned with a mild acid wash and polished.

```text
   tile 8-10 mm       =========
   slurry             ~~~~~~~~~
   mortar 1:4 (25)    .........
   RCC slab / PCC     ---------
```

## Check yourself

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

1. A suspended ground floor is used on
   A. Dry rock sites
   B. Roof slabs
   C. Basement-free hills only
   D. Damp sites, high water table or sloping ground
   Answer: D. It prevents dampness rising and dry rot. (Key point: Purpose)

2. What mortar bed is used for tiles?
   A. 20-25 mm cement-sand 1:4
   B. 100 mm 1:2:4
   C. 3 mm slurry only
   D. Lime putty
   Answer: A. Stiff bed, then slurry coat. (Key point: Mortar bed)

3. What joint width is kept using spacers?
   A. 15 mm
   B. 2-3 mm
   C. None
   D. 10 mm
   Answer: B. Joints are grouted after 24-48 hours. (Key point: Joint)

4. How long is the tile floor cured?
   A. 1 hour
   B. 60 days
   C. 3-7 days
   D. Not required
   Answer: C. Then cleaned with mild acid wash. (Key point: Curing)

## Related in Building Technology

- [Suspended ground floor](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Asuspended-ground-floor) — Building Technology, chapter 7, asked 2×
- [Solid and suspended ground floor](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Asolid-suspended-differ) — Building Technology, chapter 7, asked 2×
- [Ground floor with mosaic tiling and external wall](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Amosaic-ground-floor-wall) — Building Technology, chapter 7
- [Flooring and its types; special floor finish](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Aflooring-types-special) — Building Technology, chapter 7
- [Suspended ceiling: types, fixing, construction](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Asuspended-ceiling-fixing) — Building Technology, chapter 9, asked 6×
- [Construction of terrazzo flooring](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Aterrazzo-flooring) — Building Technology, chapter 7, asked 4×

## Related in other subjects

- [Grit chamber: purpose, construction, design](https://www.bctengineer.com/question.md?key=semester_6%2Fsanitary_engineering%3Agrit-chamber-purpose-design) — Sanitary Engineering, chapter 7, asked 4×
- [Service reservoirs: purpose and construction](https://www.bctengineer.com/question.md?key=semester_5%2Fwater_supply_engineering%3Aservice-reservoir-purpose-construction) — Water Supply Engineering, chapter 7, asked 2×
- [Skimming tank: purpose and construction](https://www.bctengineer.com/question.md?key=semester_6%2Fsanitary_engineering%3Askimming-tank-purpose-construction) — Sanitary Engineering, chapter 7
- [Pit privy: purpose and construction](https://www.bctengineer.com/question.md?key=semester_6%2Fsanitary_engineering%3Apit-privy-purpose-construction) — Sanitary Engineering, chapter 9