BCGBC4010A Apply structural principles to residential low-rise constructions

Footing systems

Topic activity
Question 1 of 18
What is the minimum bearing capacity when using strip footings for a brick veneer dwelling? 
A.	50 kPa
B.	100 kPa
C.	10 kPa
D.	150 kPa
The correct answer is B - 100 kPa. That is actually the requirement for brick veneer, solid brick and cladding.

Question 2 of 18
What can be used for stump pad footings?
A.	Timber and concrete only
B.	Steel and concrete only
C.	Timber only
D.	Timber, concrete and steel
The correct answer is D - Timber, concrete and steel. These three materials are commonly used.

Question 3 of 18
What does wetting of the soil cause?
A.	Volume increase
B.	Volume decrease
C.	Increase in soil suction force
D.	All of the above
The correct answer is A - Volume increase. Wetting causes the soil to expand.

Question 4 of 18
What is the most stable soil?
A.	Sand
B.	Rock
C.	Slightly reactive clay 
D.	Extremely reactive clay
The correct answer is B - Rock. Rock is the most stable soil as it has no ground movement.

Question 5 of 18
What depth should pad footings be in moderately reactive clay soils?
A.	400 mm
B.	500 mm
C.	1,000 mm
D.	150 mm
The correct answer is B - 500 mm. It must be deeper than for Class A or Class S soils.

Question 6 of 18
Reinforced footings are required for what type of buildings?
A.	Solid brick only
B.	Brick veneer only
C.	Concrete block only
D.	All of the above
The correct answer is D - All of the above. All of these structures require reinforced footings.

Question 7 of 18
What does the symbol Df denote?
A.	Depth of frame
B.	Depth of strip footing
C.	Depth of full masonry wall
D.	Depth of pad footing
The correct answer is B - Depth of strip footing. This is the symbol for the overall depth of strip footing.

Question 8 of 18
What is the spacing required for gridded footings to support full masonry?
A.	6 m maximum in one direction
B.	6 m minimum in one direction
C.	6 m maximum in both directions
D.	6 m minimum in both directions
The correct answer is C - 6 m maximum in both directions. A spacing of 6 m is required when supporting full masonry.

Question 9 of 18
When are vapour barriers required in strip footing excavations?
A.	The excavation exceeds 700 mm depth in highly reactive clay soil
B.	The excavation exceeds 500 mm depth in extremely reactive clay soil
C.	The excavation exceeds 700 mm in sand
D.	The excavation exceeds 500 mm in slightly reactive clay soil
The correct answer is A - The excavation exceeds 700 mm depth in highly reactive clay soil. This is to prevent ‘drag down’ from the ground to the footing.

Question 10 of 18
The base of a stepped footing excavation is always what direction?
A.	Vertical and parallel to the NGL
B.	Horizontal and parallel to the NGL
C.	Vertical but not necessarily parallel
D.	Horizontal but not necessarily parallel
The correct answer is B - Horizontal and parallel to the NGL. It must be horizontal and parallel.

Question 11 of 18
What is the most common slab footing?
A.	Plain footing slab
B.	Waffle raft slab
C.	Stiffened footing slab
D.	Stiffened raft slab
The correct answer is D - Stiffened raft slab. This is the most common and the simplest.

Question 12 of 18
What is the advantage of using footing slabs?
A.	They need only simple form work
B.	They need only simple excavation
C.	They do not need internal beams
D.	All of the above
The correct answer is D - All of the above. 

Question 13 of 18
External walls in footing slab constructions must be strong enough to perform what task?
A.	Support the fill
B.	Support the internal beams
C.	Support load bearing walls
D.	Support the footings
The correct answer is A - Support the fill. This is because the fill is usually restrained at the external walls.

Question 14 of 18
What is waffle raft slab construction most suitable for?
A.	Rock sites
B.	Sand sites
C.	Highly reactive clay sites
D.	Class P sites
The correct answer is C - Highly reactive clay sites. Highly reactive clay sites are the most suitable because the slab ribs are formed on top of the ground.

Question 15 of 18
Concrete is poured in bulk piers approximately how many mm below the NGL?
A.	500 mm
B.	800 mm
C.	1,200 mm
D.	200 mm
The correct answer is A - 500 mm. It is poured at this depth below the NGL or the FGL.

Question 16 of 18
What does the term ‘belling’ involve?
A.	Decreasing the base of a pier where soil capacity is low 
B.	Increasing the base of a pier where soil capacity is low
C.	Decreasing the diameter of a pier where soil capacity is low
D.	Increasing the diameter of a pier where soil capacity is low
The correct answer is B - Increasing the base of a pier where soil capacity is low. This spreads the forces over a greater bearing area.

Question 17 of 18
What must all DPC material be?
A.	Of polyethylene
B.	Water resistant
C.	Impact resistant 
D.	Corrosion resistant
The correct answer is B - Water resistant. All the various acceptable materials are water resistant.

Question 18 of 18
Termites can be prevented from entering when graded stone and steel mesh are placed or secured in what manner?
A.	At exposed edges
B.	Around pipes
C.	Around cracks in the concrete
D.	All of the above
The correct answer is D - All of the above. All of these places are potential entry points for termites.

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