WHAT IS FOUNDATION:
A foundation (also called a groundsill) is a structure that transfers loads to the earth. Foundations are generally broken into two categories: shallow foundations and deep foundations.
A foundation (also called a groundsill) is a structure that transfers loads to the earth. Foundations are generally broken into two categories: shallow foundations and deep foundations.
- Shallow Foundation
a type of foundation that is used when the earth directly beneath a structure has sufficient bearing capacity to sustain the loads from the structure - Deep Foundation
a type of foundation that is used when the soil near the ground surface is weak
Shallow Foundations
1. Cantilever Wall
a type of foundation wall that consists of a stem and a base slab that is held in equilibrium by self-weight, horizontal soil pressure, and the reaction of the base structure acting upward
2. Combined Footing
a footing that is used under two or more vertical elements to prevent overturning from eccentric loading
3. Mat/Raft Foundation
a large slab foundation that is used instead of multiple spread footings
4. Spread Footing
the most widely used type of shallow foundation that is designed to receive the concentrated loads directly on the centroid to prevent unequal pressure distribution and overturning of the footing
5. Strip Footing
an extended footing used under foundation walls; strip footings are used in basements, crawlspaces, and for slabs-on grade.
6. Wall Footing
elongated spread footings that transfer loads from load bearing walls. Wall footings are used in substructures such as slabs-on-grade, crawlspaces and basements.
Deep Foundations
1. Battered Piles
an inclined pile that is used that can resist lateral forces as well as vertical forces
2. Bearing Piles
a type of pile that is used to resist lateral loads and uplift forces
3. Caissons
a type of deep foundation that is achieved by casting concrete into drilled holes
4. Friction Piles
a type of pile that resists loads by friction and transfers loads to the surrounding soil using the adhesive resistance between the pile surface and its surrounding soil
5. Pile
a long and slender deep foundation that is driven pushed into the ground
THE DIFFERENCE BETWEEN MAT FOUNDATION & SPREAD FOOTING FOUNDATION
MAT FOUNDATION
Mat foundation for use in construction work in a pit excavation in the ground, a foundation lattice framework is provided by juxtaposing concrete lattice frames on the bottom of the excavation. Foundation blocks are placed in alignment on the foundation lattice framework so as to be astride adjacent lattice frames, adjacent joints of the foundation blocks being so disposed as to be located over an open space of the foundation lattice framework. There, joints are connected and secured to each other by metal implements, a reinforcing bar being located on connecting metal implements. The lowermost ends of the reinforcing bar extends to the open space of the foundation lattice framework, which open space of the foundation blocks are filled with concrete.
MAT FOUNDATION
Mat foundation for use in construction work in a pit excavation in the ground, a foundation lattice framework is provided by juxtaposing concrete lattice frames on the bottom of the excavation. Foundation blocks are placed in alignment on the foundation lattice framework so as to be astride adjacent lattice frames, adjacent joints of the foundation blocks being so disposed as to be located over an open space of the foundation lattice framework. There, joints are connected and secured to each other by metal implements, a reinforcing bar being located on connecting metal implements. The lowermost ends of the reinforcing bar extends to the open space of the foundation lattice framework, which open space of the foundation blocks are filled with concrete.
"The mat (or raft) foundation can be considered a large footing extending over a great area, frequently an entire building. All vertical structural loadings from columns and alls are supported on the common foundation. Typically, the mat is utilized for conditions where a preliminary design indicates that individual columns or footings would be undesirably close together or try to overlap. The mat is frequently utilitzed as a method to reduce or distribute building loads in order to reduce differential settlement between adjacent areas. To function properly, the mat structure will be more rigid and thicker than individual spread footing." A mat foundation is typically used when there are poor and weak soil conditions.
FOOTING FOUNDATION:
A firm foundation, including properly installed footings of adequate size to support the structure and prevent excessive settlement, is essential to the satisfactory performance of buildings including raised floor systems.
Foundation systems are often classified as shallow or deep foundations, depending on the depth of the load-transfer member below the super-structure and the type of transfer load mechanism. The required foundation system depends on the strength and compressibility of the site soils, the proposed loading conditions, and the project performance criteria (i.e. total settlement and differential settlement limitations).
Foundation designs are based on the assumed bearing capacity of the soil at the building site (see Table 7). In construction sites where settlement is not a problem, shallow foundations provide the most economical foundation systems. Shallow foundation construction is typically utilized for most residential and light commercial raised floor building sites.
TYPES OF FOOTINGS
Footing requirements are generally covered in the building code and sized in accordance with the bearing capacity of the soil and the weight of the building. In areas subject to seasonal frost, the bottom of the footing must be placed below the frost line to prevent damage to the footing and structure due to frost heave. Typical footing types include:
1. spot footings
2. continuous spread footing
3. grade beam footing
Spot Footings
A spot or pad footing is used to support a single point of contact, such as under a pier or post. A spot footing is typically a 2' by 2' square pad, 10" to 12" thick, and made with reinforced concrete rated to 3,000 to 5,000 pounds per square inch (psi) in compression.
Continuous Spread Footing
A continuous spread footing is commonly used to provide a stable base around the entire perimeter of a structure. Buildings with spread footings often include interior spot footings. A spread footing supports the weight (load) from the exterior or foundation walls. The footing thickness provides the strength needed to support the weight. The wider width of the footing base creates a large area to transfer this weight to the ground and to prevent settlement.
The dimensions of a continuous spread footing vary according to the soil conditions under the building, the load placed on the footing, and the construction style of the structure being supported. It is common practice to make the footing thickness equal to the thickness of the foundation wall, and to provide a footing projection on each side of the foundation wall equal to one-half the foundation wall thickness. Spread footings are frequently 16" to 24" wide, 6" to 16" thick, and made with reinforced concrete rated to 2,000 to 5,000 psi in compression. Table 9 lists the minimum footing widths required for a range of allowable bearing capacities and building sizes.
Grade Beam Footing
A grade beam footing is a continuous reinforced-concrete member used to support loads with minimal bending. Grade beams are capable of spanning across non-load bearing areas, and are commonly supported by soil or pilings. A continuous grade beam is frequently constructed by digging a trench at least 8" wide to the depth needed to span the distance between supports. Grade beam footings differ from continuous spread footings in how they distribute loads. The depth of a grade beam footing is designed to distribute loads to bearing points, while the width of a continuous spread footing is designed to transfer loads to the ground.
A firm foundation, including properly installed footings of adequate size to support the structure and prevent excessive settlement, is essential to the satisfactory performance of buildings including raised floor systems.
Foundation systems are often classified as shallow or deep foundations, depending on the depth of the load-transfer member below the super-structure and the type of transfer load mechanism. The required foundation system depends on the strength and compressibility of the site soils, the proposed loading conditions, and the project performance criteria (i.e. total settlement and differential settlement limitations).
Foundation designs are based on the assumed bearing capacity of the soil at the building site (see Table 7). In construction sites where settlement is not a problem, shallow foundations provide the most economical foundation systems. Shallow foundation construction is typically utilized for most residential and light commercial raised floor building sites.
TYPES OF FOOTINGS
Footing requirements are generally covered in the building code and sized in accordance with the bearing capacity of the soil and the weight of the building. In areas subject to seasonal frost, the bottom of the footing must be placed below the frost line to prevent damage to the footing and structure due to frost heave. Typical footing types include:
1. spot footings
2. continuous spread footing
3. grade beam footing
Spot Footings
A spot or pad footing is used to support a single point of contact, such as under a pier or post. A spot footing is typically a 2' by 2' square pad, 10" to 12" thick, and made with reinforced concrete rated to 3,000 to 5,000 pounds per square inch (psi) in compression.
Continuous Spread Footing
A continuous spread footing is commonly used to provide a stable base around the entire perimeter of a structure. Buildings with spread footings often include interior spot footings. A spread footing supports the weight (load) from the exterior or foundation walls. The footing thickness provides the strength needed to support the weight. The wider width of the footing base creates a large area to transfer this weight to the ground and to prevent settlement.
The dimensions of a continuous spread footing vary according to the soil conditions under the building, the load placed on the footing, and the construction style of the structure being supported. It is common practice to make the footing thickness equal to the thickness of the foundation wall, and to provide a footing projection on each side of the foundation wall equal to one-half the foundation wall thickness. Spread footings are frequently 16" to 24" wide, 6" to 16" thick, and made with reinforced concrete rated to 2,000 to 5,000 psi in compression. Table 9 lists the minimum footing widths required for a range of allowable bearing capacities and building sizes.
Grade Beam Footing
A grade beam footing is a continuous reinforced-concrete member used to support loads with minimal bending. Grade beams are capable of spanning across non-load bearing areas, and are commonly supported by soil or pilings. A continuous grade beam is frequently constructed by digging a trench at least 8" wide to the depth needed to span the distance between supports. Grade beam footings differ from continuous spread footings in how they distribute loads. The depth of a grade beam footing is designed to distribute loads to bearing points, while the width of a continuous spread footing is designed to transfer loads to the ground.
St. David Square will be using MAT FOUNDATIONS to give our unit owners a peace of mind!