8/12/2019 Foundations and Footings

http://slidepdf.com/reader/full/foundations-and-footings 1/4

Sheree Ann M. Labe

Bachelor of Science in Architecture

ARCHT 26 – A

ASSIGNMENT

Shallow Foundation

Shallow or spread foundations are employed when stable soil of adequate bearing capacity occurs

relatively near to the ground surface. They are placed directly below the lowest part of a substructure

and transfer building loads directly to the supporting soil by vertical pressure.

Deep Foundation

Deep foundations are employed when the soil underlying a foundation is unstable or of inadequate

bearing capacity. They extend down through unsuitable soil to transfer building loads to a more

appropriate bearing stratum of rock or dense sands and gravels well below the superstructure.

Pole Foundation

Pole Foundation elevate timber structures above the ground plane require minimal, and preserve the

natural features and existing drainage patterns of a site. They are particularly useful when building on

steep and in areas subject to periodic flooding.

Pile Foundation

A pile foundation is a system of end-bearing or friction piles, pile caps, and tie beams for transferring

building loads down to a suitable bearing stratum.

Caisson Foundation

Caissons are cast in-place, plain or reinforced concrete piers formed by boring with a large auger or

excavating by hand a shaft in the earth to a suitable bearing stratum and filling the shaft with a

concrete. For this reason, they are also referred to as drilled piles or piers.

Underpinning

Underpinning refers to the process of rebuilding or strengthening the foundation of an existing building,

or extending it when a new exaction in adjoining property is deeper than the existing foundation.

Footing

A foundation unit constructed in brickwork, masonry or concrete under the base of a wall or column for

the purpose of distributing the load over a large area. Footings are critical to the structural stability of a

cottage. Footings are designed based on site topography, soil type, stability, and any other local

requirements during the design process.

8/12/2019 Foundations and Footings

http://slidepdf.com/reader/full/foundations-and-footings 2/4

Sheree Ann M. Labe

Bachelor of Science in Architecture

ARCHT 26 – A

ASSIGNMENT

Types of footings

A. Strip Footings

They are suitable for stable sites (Class A or S sites) that are flat or sloping. Timber framed construction

with brick up to floor level may be constructed onto strip footings in reactive clay areas (Class M and H

sites).

B.Pier and beam footings

Footing beams for brick and brick veneer cottages on reactive clay soils (Class M and H) generally

require piering to stable ground. Piering is always required where footings are influenced by adjacent

drainage or Water Board sewer mains. Sites containing extremely reactive ground or uncontrolled filling

require piering for footings of all types of construction.

C. Foundation Slabs (Raft Slabs)

Types include: the conventional concrete slab with perimeter and internal beams and the (waffle pod)

slab which has internal ribs 110mm wide spaced at 1200mm centres in both directions. This type of

footing is used for all types of construction on all site classifications, however, there usage is generally

8/12/2019 Foundations and Footings

http://slidepdf.com/reader/full/foundations-and-footings 3/4

Sheree Ann M. Labe

Bachelor of Science in Architecture

ARCHT 26 – A

ASSIGNMENT

restricted to sites containing less than 2.0m of fall. For steeply sloping sites other types of footingconstruction should be considered.

8/12/2019 Foundations and Footings

http://slidepdf.com/reader/full/foundations-and-footings 4/4

Sheree Ann M. Labe

Bachelor of Science in Architecture

ARCHT 26 – A

ASSIGNMENT

D. Elevated ConstructionHomes on steep sites or sites prone to flooding generally have elevated floors supported on timber

poles, steel posts, brick piers or concrete columns. Bracing is required to control sidesway. Timber poles

can be of treated pine or hardwood. Treated pine poles can be set into concrete filled holes drilled into

the ground while hardwood poles should be supported by a concrete plug in the base of the drilled pier

hole which is filled with gravel.