1. Weekend Cabin Retreat Project Foundations and Foundation Plans
Sacramento City College
EDT 300
EDT Foundation Plan Design

2. EDT 300 - Foundation Plan Design
Objectives
Describe the procedure for staking out a house location.
List the major considerations when designing a footing for a residential foundation.
Analyze a typical floor plan to determine the appropriate foundation.
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3. EDT 300 - Foundation Plan Design
Masonry Foundation
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4. EDT 300 - Foundation Plan Design
Wood Foundation
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5. Staking Out House Location
The plot plan provides the necessary dimensions required for staking out the location of the house on the lot.
Tools for staking out:
Measuring tape
Contractor's level
Transit (if required)
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6. Staking Out House Location
First Step
locate each corner by laying off the distances indicated on the plot plan.
Drive a stake into the ground at the location of each corner of the foundation to identify its position.
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7. Staking Out House Location
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8. Staking Out House Location
Square corners may be laid out using the unit method.
These proportions define a right triangle and establish a 90 angle corner.
EDT Foundation Plan Design

9. Staking Out House Location
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10. Staking Out House Location
Batter boards are used to retain the location of the foundation during excavation and construction.
Are constructed of 2 x 4 stakes driven into the ground about 4 feet outside the footing line.
A 1 x 6 board is nailed horizontally to the stakes so all are level and in the same horizontal plane. (They will have the same elevation.)
EDT Foundation Plan Design

11. Staking Out House Location
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12. Staking Out House Location
A strong cord is stretched across the boards at opposite ends of the building and located directly above the corner stakes.
A plumb bob is used for accurate placement of each stake.
This is done for each side of the building.
A saw kerf (cut) is usually made at the exact point on the horizontal batter board where the string is located.
This prevents movement of the string along the board.
EDT Foundation Plan Design

13. Staking Out House Location
After cuts are made in all eight batter boards, the outlines of the house will be located.
A control point is needed to determine the depth of excavation and foundation wall height.
The corner with the highest elevation is usually selected for this purpose.
The finished floor should be at least 8 inches above the grade.
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14. EDT 300 - Foundation Plan Design
Excavation
In excavating for footings and foundation walls, the top soil is usually removed using a bulldozer or tractor with a blade.
This soil is saved for final grading.
A trencher or backhoe may be used to excavate for foundations when either slab construction or a crawl space is planned.
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15. EDT 300 - Foundation Plan Design
Excavation
In excavating for a basement, a backhoe used.
Selection of excavating equipment is determined by the size of the excavation and type of soil.
Excavation for footings should extend down to a minimum of 6 in. into undisturbed earth.
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Excavation
It must also be at least 6 in. below the average maximum frost penetration depth.
Local codes usually specify the minimum footing depth for a given area.
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Excavation
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Excavation
No backfilling should be permitted under the proposed footings, because uneven settling of the house may occur.
Footings on rock. About 6 in. of the rock should be removed under the proposed footing and replaced with compacted sand to equalize settling.
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19. EDT 300 - Foundation Plan Design
Excavation
Sites which have recently been filled and regraded: the footings should extend down to the original undisturbed earth.
Unless soil tests prove that the earth is sufficiently compacted to properly support the structure.
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20. EDT 300 - Foundation Plan Design
Excavation
Excavation must be large enough to allow space to work when constructing the foundation wall and laying drain tile.
The steepness of the back slope will depend on the type of soil encountered.
Sandy soil is likely to cave-in and,requires a gentle back slope.
Clay may be nearly vertical.
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Footing Shapes
Footings increase the supporting capacity of the foundation wall by spreading the load over a larger area.
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Footing Shapes
If a foundation was built on rock, a footing would not be necessary.
Most houses are not built on such solid material and therefore need footings to support the heavy loads.
The size and type of footing should be
suitable for the weight of the building and
soil bearing capacity.
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Footing Shapes
Footings for most residential structures are made of poured concrete.
The size of footing required is commonly determined by using the foundation wall thickness as a basis for its proportions.
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Footing Shapes
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25. EDT 300 - Foundation Plan Design
Footing Shapes
This size footing is designed for most normal soil conditions ranging from sand to clay.
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Footing Shapes
Foundation walls should be centered along the footing.
The footing will project beyond each side of the foundation wall a distance equal to one-half the thickness of the foundation wall.
If the soil load bearing capacity is very poor, the size of footings should be increased and reinforced with steel.
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Footing Shapes
The footings must be large enough to minimize the effects of:
settlement of the structure.
unequal compressibility of the soil.
to reduce cracking.
The weight of most homes is greater on two of the four walls which causes unequal loading.
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Footing Shapes
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29. EDT 300 - Foundation Plan Design
Foundation Walls
Foundation walls extend from the first floor to the footing.
A foundation wall may also be a basement wall.
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Foundation Walls
Materials used to build foundation walls include
cast (poured) concrete
concrete block
pressure-treated wood
stone or brick in rare instances
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Foundation Walls
Cast concrete and concrete block are widely used in residential structures.
Pressure-treated wood foundations are gaining acceptance for residential structures.
Brick is much more expensive than cast concrete, block, or wood, and is seldom used.
Stone was once used extensively, but is no longer of significance as a foundation material.
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Footing Materials
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33. EDT 300 - Foundation Plan Design
Footing Materials
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34. EDT 300 - Foundation Plan Design
Footing Materials
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35. EDT 300 - Foundation Plan Design
Foundation Walls
Foundation walls are of four basic types:
T-foundation
slab foundation
pier or post foundation
permanent wood foundation
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Foundation Types
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Foundation Types
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Foundation Walls
The type chosen for a particular situation will depend upon
the weight to be supported
load bearing capacity of the soil
location of the foundation in the building
climate
local codes
preferred building practice.
All should be considered when designing a foundation.
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T-Foundations
Most common foundation type
Looks like an inverted T.
The foundation and footing are usually two separate parts but may be cast as a single unit.
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T-Foundations
Concrete for footings of a T-foundation is usually placed in forms made from construction lumber.
The form boards are nailed to stakes once they are level.
Stakes prevent movement while the concrete is being cast.
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T-Foundations
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Slab Foundations
A slab foundation is an extension of a slab floor.
It is placed at the same time the floor is cast and is not a separate unit.
It is sometimes called a thickened edge slab.
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Slab Foundations
The foundation wall should extend down below the frost line, as in the case of the T-foundation.
Use of steel reinforcing bars or mesh is recommended for the slab foundation to prevent cracking due to settling.
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Slab Foundations
Some of the primary advantages of the slab foundation
requires less time, expense, and labor to construct.
no separate footing is required, excavation is not as extensive as for the T-foundation.
Less time is required since the entire foundation and floor is placed in one operation.
EDT Foundation Plan Design

45. Pier and Post Foundations
Many situations in residential construction lend themselves to the use of piers, columns and posts.
Cheaper and just as satisfactory to use piers rather than the T-foundation under parts of the building.
Example: a crawl space is planned and the distance is too great for a single span, the pier foundation is a logical choice,
EDT Foundation Plan Design

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47. Pier and Post Foundations
Another common application: a basement or garage where the distance is too great to span with floor joists.
Lally columns are used to support a beam that in turn supports the joist., rather than construct a bearing wall partition.
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49. Pier and Post Foundations
Basic difference between a pier and column is the length.
Piers are usually much shorter and ordinarily located under the house.
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50. Pier and Post Foundations
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51. Pier and Post Foundations
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52. Pier and Post Foundations
The column is composed of two pieces; a footing and post.
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53. Pier and Post Foundations
The footing is usually square or rectangular
The post may be masonry, steel, or pressure-treated wood.
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55. EDT 300 - Foundation Plan Design
Wood Foundations
Wood foundations are known by several names:
the permanent wood foundation (PWF)
the all-weather wood foundation (AWWF)
the treated wood foundation.
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Wood Foundations
A wood foundation is a below grade pressure-treated plywood-sheathed stud wall.
The wood foundation is attractive in climates where typical (concrete and masonry) foundation work stops in freezing or rainy weather.
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Wood Foundations
All wood parts are pressure-treated with chemical solutions that make the wood fibers useless as food for insects or fungus growth.
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Wood Foundations
The system is accepted by
the Federal Housing Administration (FHA)
the Department of Housing and Urban Development (HUD),
Farmers Home Administration (FmHA)
the major model building codes
It is rapidly gaining acceptance in state and local codes as well.
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Wood Foundations
The system may be used in full basement or crawl space construction
It is adaptable to most any site and light-frame building design.
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Wood Foundations
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Wood Foundations
Crawl spaces
A trench is excavated to receive the footing and foundation wall.
The trench should be at least 12 in. deep regardless of the frost depth.
The depth of the excavation should be below the average maximum frost penetration depth.
2 in. of sand or 6 in. of crushed stone or gravel are raked smooth in the bottom of the trench.
This provides a level base for the footing.
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Wood Foundations
The footing is generally 12” wide.
Local codes may require wider footings.
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Beams and Girders
Most residences have spans too great to use unsupported floor joists.
A beam or girder is required to support the joists and prevent excessive sagging.
The beam is usually placed an equal distance from each outside wall or under a bearing wall.
A bearing wall is designed to support part of the load of the structure.
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Beams and Girders
Beams may be either wood or metal.
Wood beams are of two types built-up and solid.
Built-up beams
are used more frequently
easier to handle
more readily available
do not check to the extent of solid beams.
However, solid beams are generally stronger and more fire-resistant.
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Beams and Girders
Two types of steel beams are commonly used: S-beams and wide-flange beams,
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Beams and Girders
The wide-flange beam
will support greater weight
is more stable than the standard S beam
it is more popular for residential construction.
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Beams and Girders
Calculation of the size beam needed is based on the weight of the structure.
Weights are designated either as live loads or dead loads.
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Beams and Girders
Live loads are those fixed or moving weights, which are not a structural part of the house.
Examples include:
furniture
occupants
snow on the roof
wind, etc.
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Beams and Girders
Dead loads are those static or fixed weights of the structure itself.
Examples of dead loads are the weights of:
roofing
foundation walls
siding
joists, etc.
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71. EDT 300 - Foundation Plan Design

72. Building Structure Loads
First/Second Floor
Live load plus dead load = 50 pounds per square foot.
Ceiling
Live load plus dead load = 30 pounds per square foot.
Walls
Dead load = 10 pounds per square foot.
Roof
No load on the beam. Exterior walls generally support the roof.
EDT Foundation Plan Design

73. Building Structure Loads
Weight Calculations
The example used is for a two-story frame structure which is 28'-O" x 40'-O".
Width x length = Area of the house.
28' x 40' = 1120 sq. ft. for each floor.
8' x 40' = 320 sq. ft. of wall area for each wall.
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74. Building Structure Loads
Weight per sq. ft. x number of sq. ft. = total wt.
Weight of first floor
(1120 sq. ft. x 50 lbs./sq. ft.) = 56,000 lbs.
Weight of second floor
Weight of ceiling
(1120 sq. ft. x 30 lbs./sq. ft.) = 33,600 lbs.
Weight of roof on beam
(none in this example) 0 lbs.
Total ,600 lbs.
EDT Foundation Plan Design

75. Building Structure Loads
One-half of the total weight bears on the center beam.
(1/2 x 145,600 pounds) = 72,800 lbs.
Weight of first floor wall
(320 sq. ft. x 10 lbs./sq. ft.) = 3,200 lbs.
Weight of second floor wall
Weight bearing on beam = 79,200 lbs.
One “kip” is 1,000 pounds
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76. Building Structure Loads
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77. Building Structure Loads
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78. Building Structure Loads
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79. Building Structure Loads
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80. EDT 300 - Foundation Plan Design
Lintels
A lintel is a horizontal structural member that supports the load over an opening such as a door or window.
Lintels may be constructed of
precast concrete
cast-in-place concrete
lintel blocks
steel angle.
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Lintels
When lintels are used in a masonry wall, the ends must extend at least 4 in. into the wall on either side of the opening.
Common precast lintel sizes for residential construction are 4" x 8", 4" x 6", and 8" x 8".
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Lintels
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Lintels
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Lintels
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Lintels
Lintels are also made of angle steel.
They are available as equal angles (both legs the same size) or as unequal angles.
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Lintels
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Lintels
Openings in cast concrete walls do not require lintels.
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Concrete and Masonry
Concrete is the result of combining cement, sand, aggregate (usually stone or gravel), and water.
Cement is composed of a mixture of lime, silica, alumina, iron components, and gypsum.
The proportions of the ingredients will vary with the requirements.
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Concrete and Masonry
Sidewalks, driveways, footings, and basement floors usually contain one part cement, three parts sand, and five parts aggregate.
Footings as well as concrete floors must have both a minimum compressive strength of 3,000 psi and minimum cement content of 5 bags (470 lbs.) per cubic yard.
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Concrete and Masonry
The amount of water used will most likely be 6 or 7 gallons for each bag of cement (normally 94 pounds per bag).
Concrete cures over a long period of time and should be kept moist for several days after it is placed.
Failure to do this reduces strength and may harm the exposed surface.
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Concrete and Masonry
Temperature also affects the setting time of concrete.
Cold weather slows down the process and concrete should not be allowed to freeze before it has set.
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Concrete and Masonry
Concrete is ordered by the cubic yard (27 cubic foot).
The consistency is generally specified by how many bags of cement are contained in each yard of mix.
A "five-bag mix" is considered minimum for most jobs.
A "six-bag mix" will produce a stronger product and should be used when high strength or reinforcing is required.
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Concrete and Masonry
When concrete is being placed, it commonly traps air pockets within the mixture.
These air pockets are worked out by vibrating or tamping.
This action helps to form a more dense material and removes weak spots due to air pockets.
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Concrete and Masonry
After the concrete has been placed, a screed is used to smooth the surface.
The screed is a long straightedge, usually a board, which is worked back and forth across the surface.
This action brings excess water to the surface and settles the aggregate.
Power screeds are a so available for large jobs.
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95. EDT 300 - Foundation Plan Design
Concrete and Masonry
When screeding is finished, the surface is then worked over with a float.
A float is a short board about a foot long with a handle attached to one of the flat sides.
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96. EDT 300 - Foundation Plan Design
Concrete and Masonry
The purpose of “floating” is:
(1) to embed the large aggregate just beneath the surface,
(2) to remove any slight imperfections, lumps, and voids to produce a flat surface, and
(3) to consolidate mortar at the surface in preparation for final steel-troweling.
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Concrete and Masonry
As the mixture reaches the proper consistency, the troweling process is started.
The trowel is rectangular and is used in a circular motion.
This troweling action further hardens the surface and develops a very smooth finish.
A slightly rough surface is made by a broom.
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98. EDT 300 - Foundation Plan Design
Concrete and Masonry
When ordering concrete, one should figure only 25 cubic feet to the yard.
Some of the material will remain in the mixer, some will be spilled, and forms may sag.
Experience has shown that it is better to have a little more concrete than you need than to have too little.
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99. EDT 300 - Foundation Plan Design
Concrete and Masonry
Large areas of concrete crack from expansion and contraction due to changes in temperature and moisture content.
Cracking may be minimized or controlled by contraction joints.
Contraction joints should be placed in line with interior columns, at changes in the width of the slab, or at maximum spacing of about 20 ft.
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Concrete and Masonry
Joints are formed by cutting grooves in the freshly placed concrete with a jointing tool.
They can be cut into the slab with a power saw after the concrete has hardened.
The depth of joints or grooves should be one-fourth the thickness of the slab.
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Concrete and Masonry
A concrete slab is usually placed directly on firmly compacted sand 4 to 6 inches thick.
Dry sand should be dampened to prevent absorption of too much mixing water from the fresh concrete.
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Concrete and Masonry
The sand should be
thoroughly compacted to prevent settlement of the slab.
sloped toward the floor drains to ensure a uniform slab thickness.
Floor slabs usually have a minimum thickness of 4 inches.
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103. EDT 300 - Foundation Plan Design
Concrete and Masonry
Floor slabs should not be bonded to footings or interior columns.
A sand cushion 1 in. thick may be used to separate the slab from the footing.
A sleeve of three thicknesses of building felt may be wrapped around columns to break the bond.
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104. EDT 300 - Foundation Plan Design

105. EDT 300 - Foundation Plan Design
Concrete Blocks
Concrete blocks are used extensively in residential buildings for exterior and interior walls.
Concrete blocks are hollow concrete masonry units, usually 8" x 8" x 16" in dimension.
The actual size is 7 5/8" x 7 5/8" x 15 5/8".
These dimensions allow for a 3/8 in. mortar joint.
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106. EDT 300 - Foundation Plan Design
Concrete Blocks
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107. EDT 300 - Foundation Plan Design
Concrete Blocks
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108. EDT 300 - Foundation Plan Design
Concrete Blocks
The distance from the center line of one,mortar joint to the center line of the next will be 8 or 16 inches.
EDT Foundation Plan Design