Grade 10 building construction – Introduction to Building Construction Quiz
1. What is the primary purpose of a building foundation?
Foundations carry the weight of the structure and spread it to the soil so the building remains stable and does not sink or tilt.
2. Which of the following describes a shallow foundation?
Shallow foundations (e.g., strip, pad, raft) are used when suitable soil is close to the surface and can safely support the loads.
3. Which foundation type is most suitable for a single column supporting heavy load?
Isolated pad footings are used under single columns to spread the column load over a small area of soil.
4. What is a strip footing commonly used for?
Strip footings run continuously under walls to distribute wall loads evenly to the ground.
5. What is a raft (mat) foundation best used for?
Raft foundations cover the building footprint and spread loads across the whole area, reducing pressure on weak soils.
6. Which of the following is a deep foundation type?
Pile foundations transfer loads through weak surface soils to deeper stronger layers and are therefore deep foundations.
7. What does 'safe bearing capacity' of soil mean?
Safe bearing capacity is the allowable stress the soil can take to avoid unacceptable settlement or failure.
8. Which soil type generally has the highest bearing capacity for foundations?
Dense rock and well-compacted gravels provide strong support and high bearing capacity for foundations.
9. Why is it important to remove topsoil before laying foundations?
Topsoil is loose and organic; if left under foundations it can decompose or settle, causing uneven settlement.
10. Which test is commonly used on site to estimate the bearing capacity of soil quickly?
The plate load test applies load to a steel plate on the ground to measure settlement and estimate bearing capacity.
11. What is differential settlement?
Differential settlement is uneven settling that can crack walls and damage the building structure.
12. Which material is commonly used to protect foundations from moisture rising into walls?
A DPC is a waterproof layer (often plastic or bitumen sheet) placed above the foundation to stop rising damp entering the walls.
13. In Kenya, which factor commonly affects the required depth of a foundation?
Soil conditions and the level of groundwater determine how deep foundations must be to find firm, dry bearing strata.
14. Why are reinforcement bars (steel) used in concrete foundations?
Concrete is strong in compression but weak in tension; steel reinforcement helps resist tensile forces and reduces cracking.
15. Which is a common cause of foundation failure?
Failing to investigate soil or design correctly can cause undersized foundations and lead to excessive settlement or collapse.
16. What is meant by 'bearing stratum' under a foundation?
The bearing stratum is the ground layer with adequate strength to carry the building's loads without excessive settlement.
17. When should a pile foundation be considered?
Piles are used to bypass weak upper soils and transfer loads to deeper competent layers or rock.
18. Which of the following is NOT a function of good foundation design?
Foundations improve stability and resist forces, but they do not eliminate the need for maintenance over a building's life.
19. What is the purpose of compacting soil under a foundation base?
Compaction reduces voids in the soil, increasing strength and reducing the chance of future settlement under loads.
20. Which foundation type would be used for a building on expansive clay that swells when wet?
Expansive clay near the surface can cause movement; deep foundations reach stable soil or rock below the active clay layer.
21. What should be done if a building site has a high water table before constructing foundations?
High groundwater can weaken soils and cause damp problems; drainage, dewatering, waterproofing, or deep foundations are used to manage it.
22. What is the correct order of steps when preparing a foundation trench?
Proper preparation removes unsuitable topsoil, sets the correct excavation depth, compacts the base, and installs formwork and reinforcement before concreting.
23. Which statement about isolated footings (pad footings) is true?
Isolated footings support single columns by enlarging the base area to reduce bearing pressure on the soil.
24. How does vegetation near foundations affect them?
Large trees can extract moisture and shrink soils like clay, causing settlement or cracks; roots may also damage structures.
25. Why is a building's load path important in foundation design?
Understanding load paths ensures footings and foundations are provided under points that carry structural loads to the ground.