Grade 10 building construction – Introduction to Building Construction Quiz

Foundations carry the weight of the structure and spread it to the soil so the building remains stable and does not sink or tilt.

Shallow foundations (e.g., strip, pad, raft) are used when suitable soil is close to the surface and can safely support the loads.

Isolated pad footings are used under single columns to spread the column load over a small area of soil.

Strip footings run continuously under walls to distribute wall loads evenly to the ground.

Raft foundations cover the building footprint and spread loads across the whole area, reducing pressure on weak soils.

Pile foundations transfer loads through weak surface soils to deeper stronger layers and are therefore deep foundations.

Safe bearing capacity is the allowable stress the soil can take to avoid unacceptable settlement or failure.

Dense rock and well-compacted gravels provide strong support and high bearing capacity for foundations.

Topsoil is loose and organic; if left under foundations it can decompose or settle, causing uneven settlement.

The plate load test applies load to a steel plate on the ground to measure settlement and estimate bearing capacity.

Differential settlement is uneven settling that can crack walls and damage the building structure.

A DPC is a waterproof layer (often plastic or bitumen sheet) placed above the foundation to stop rising damp entering the walls.

Soil conditions and the level of groundwater determine how deep foundations must be to find firm, dry bearing strata.

Concrete is strong in compression but weak in tension; steel reinforcement helps resist tensile forces and reduces cracking.

Failing to investigate soil or design correctly can cause undersized foundations and lead to excessive settlement or collapse.

The bearing stratum is the ground layer with adequate strength to carry the building's loads without excessive settlement.

Piles are used to bypass weak upper soils and transfer loads to deeper competent layers or rock.

Foundations improve stability and resist forces, but they do not eliminate the need for maintenance over a building's life.

Compaction reduces voids in the soil, increasing strength and reducing the chance of future settlement under loads.

Expansive clay near the surface can cause movement; deep foundations reach stable soil or rock below the active clay layer.

High groundwater can weaken soils and cause damp problems; drainage, dewatering, waterproofing, or deep foundations are used to manage it.

Proper preparation removes unsuitable topsoil, sets the correct excavation depth, compacts the base, and installs formwork and reinforcement before concreting.

Isolated footings support single columns by enlarging the base area to reduce bearing pressure on the soil.

Large trees can extract moisture and shrink soils like clay, causing settlement or cracks; roots may also damage structures.

Understanding load paths ensures footings and foundations are provided under points that carry structural loads to the ground.

A foundation's primary job is to carry the weight of the building and safely transmit those loads to the soil so the building remains stable and does not settle unevenly.

Foundations distribute loads, reduce differential settlement and give a level base. Raising a house for views is not a structural function of foundations.

A footing is the enlarged base of a foundation element (wall or column) that increases area in contact with the ground to reduce pressure on the soil.

Shallow foundations (like strip and pad footings) are placed close to the ground surface and transfer loads directly to the supporting soil.

Strip footings (continuous concrete strips under load-bearing walls) are commonly used for low-rise residential buildings in Kenya as a type of shallow foundation.

Deep foundations (piles or drilled shafts) transfer loads through weak near-surface soils down to firmer strata at greater depth.

Topsoil contains organic matter and is soft; it can compress and rot, causing settlement. Foundations must rest on firm, compacted subsoil.

Black cotton soil expands and shrinks with moisture changes, causing heave and settlement; it is common in some Rift Valley areas and needs special foundation treatment.

A raft foundation spreads the building load over a large area and is suitable where many columns exist and soil bearing capacity is low, avoiding differential settlement.

Isolated pad footings are individual footings placed under single columns to spread the concentrated column load to the soil.

Concrete is strong in compression but weak in tension; steel reinforcement provides the tensile strength needed and helps control cracks in footings.

Safe bearing capacity is the allowable pressure a soil can support from a foundation without unacceptable settlement or collapse.

Footing width is chosen so the load from the structure divided by the footing area does not exceed the soil's safe bearing capacity.

Weak soils can be improved by excavation and replacement with compacted fill, chemical stabilisation, or using piles to transfer loads to better strata.

High groundwater can weaken supporting soils, float light foundations, and interfere with concrete setting; drainage or dewatering is required.

Inspection prevents mistakes that cause failure; it verifies that excavation depth, compacted base and reinforcement are according to design before concrete is placed.

A plinth beam sits at plinth level, linking structural elements to distribute loads and reduce cracking due to differential settlement.

Reinforced concrete (cement, aggregates and steel) is durable and strong in compression and tension, making it the standard material for modern footings.

Differential settlement happens when parts of the foundation sink more than others due to variable soil strength or uneven loads, leading to cracks and structural problems.

A DPC is a layer (plastic, bitumen or other) placed above foundation level to stop capillary rise of moisture from the ground into walls and floors.

A combined footing supports two or more columns (for example when one column is near a boundary) and spreads loads so the footing remains within site limits.

Clearing roots and organic topsoil, compacting fill and providing good drainage create stable conditions that reduce settlement and moisture-related problems.

A foundation unable to safely carry loads will compress the soil excessively causing settlement, cracking and potentially unsafe structural conditions.

Field tests like the Standard Penetration Test, plate load tests, or simple bore/auger investigations help estimate soil strength and bearing capacity for foundation design.

Loose or soft pockets will cause settlement; they must be excavated and replaced with compacted engineered fill or the foundation must be extended to firmer strata.

Curing keeps concrete moist so hydration continues, producing strength and durability; poor curing leads to weak, crack-prone foundations.