WK2 FOUNDATION AND FOOTINGS Flashcards
The base is defined as the part of the building between the foundation and the top of the ground floor. What are some of the components of the base
- footings
- base walls
- piers or stumps
- the floor frame
- floor sheeting
- the concrete floor slad
- external access steps
- retaining walls
What are some surprises that can happen on site to consider
- Top soil and vegetable matter, hwo deep is the soil type? and tree roots?
- Unexpected soil conditions
- Undiscovered services ( ancient sewers, tunnels, fire mains, gas, main water lines and power supplies etc)
- Water table changes (underground rivers or oceans)
- Bad ground, soft spots
- Geologial anomalies - faults, slip zones, ‘greasy black’
- Contaminated Ground (e.g, asbestos, fuel/oil, chemical dump, nuclear waste
Theres still more…
Soil types and their ability for construction
- Rock, Expensive to excavate but very stable for foundations (little to no movement, requiring only small footings
- Clay: Most common soil type, depending on the reactivity of the clay, can require extensive foundations
- Sand
Sand or loose dry material is ideal for construction, requiring only shallow foundations. Buildings on sand often use waffle raft slabs (low cost)
Soil classification
A: Mostly sand and rock sites with LITTLE TO NO GROUND MOVEMENT from moisture changes
S: Slightly reactive clay sites with only SLIGHT GROUND MOVEMENT from moisture changes
M: Moderatively reactive clay or silt sites which can experience MODERATE GROUND MOVEMENT from moisture changes
E: Extremely recative clay sites which can experience EXTREME GROUND MOVEMENT from moisture changes
A-P: Filled sites
P: Problem Sites which include soft clay or silt or loose sands, mine subsidence, collapsing soil, soils subject to erosion. Essentially: Reactive sites subject to ABNORMAL moisture conditions or sites which CANNOT be classified otherwise
Concrete vs Cement whats the difference?
Cement is an INGREDIENT to Concrete, along with aggregates water and sand.
Concrete is the final product
Name different types of footings
- Isolated footing
- Pad footing
- Stump footing
- Continuous footing
- Strip Footing for brick veneer
- Integrated Footing slab on ground with an integral edge beam
Understand what these look like, when they are used and pros and cons
Summary of the footing process
- Excavate for the footings
- Place reinforcing steel
- install starter bars
- Penetrations for sanitary drainage and other considerations
- Engineers inspection
- Pour concrete footings
Understand piles, what when and how
What: A displacement style deep foundation where a structural member driven, screwed, drilled or otherwise installed in the ground so as to transmit loads to the soil or rock
When: Used when there is problematic/highly reactive soil, where subsoil is firm, shrinkable clay and subject to volumetric change
How: Piles taken down to a depth below shrinkable clays which then provides a more stable soil so the piles can support the ground beams
