Goodheart-Willcox Publisher | Architecture: Residential Drafting and Design | Chapter 11

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PowerPoint Presentation
PublisherThe Goodheart-Willcox Co., Inc.Tinley
Park, Illinois
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Chapter 11

• Footings, Foundations, and Concrete

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Chapter 11 Overview

• Introduction
• Staking Out House Location
• Excavation
• Footing Shapes and Specifications
• Foundation Walls
• Concrete and Masonry Basement Walls
• Beams and Girders

(continued)
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Chapter 11 Overview

• Concrete and Masonry
• Concrete Blocks
• Paving

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Learning 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.

(continued)
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Learning Objectives

• Discuss the design considerations for wood,
  concrete, and masonry foundation walls.
• Calculate the load to be supported by a beam.
• Explain the purpose of a lintel.

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Introduction

• A good foundation is very important.
• It requires careful planning and design.
• Types of foundations
• Masonry or concrete.
• All-weather wood.
• Slab type.
• Specialized CADD programs are available to aid
  the process.

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Types of Foundations

• Masonry foundation.

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Types of Foundations

• All-weather wood foundation.

(The Engineered Wood Association)
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Types of Foundations

• Slab foundation.

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Staking Out House Location

• The plot plan provides the necessary dimensions
  for staking out the house.
• The task requires a measuring tape, contractors
  level, and possibly a transit.
• Locate each corner of the house.
• Use 9-12-15 unit method for square corners.
• Check for accuracy by diagonal measurement.

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Batter Boards

• Batter boards retain location of the foundation
  during construction.
• Locate them 4' outside the footing line.
• Corner stakes located with a plumb bob.
• Batter boards are attached to the stakes.
• Determine a control point (corner).
• Finished floor should be at least 8" above the
  grade.

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Batter Boards

• Squaring a corner using the 9-12-15 unit method.

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Checking Accuracy

• Measuring diagonals.

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Batter Boards in Place
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Excavation

• Top soil should be removed and saved.
• A backhoe generally used to excavate.
• Excavation for footings should extend at least 6"
  into undisturbed earth.
• The depth of excavation should also be at least
  6" below frost penetration.
• No backfilling under footings.
• Soil tests determine soil suitability.

(continued)
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Excavation

• Excavation must be large enough to allow space to
  work on the foundation.
• Excavation wall should slope away from the bottom
  of the excavation.
• Slope angle will depend on soil type.
• Sandy soil requires a gentle slope.
• Wall may be nearly vertical in clay.

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Frost Penetration Chart

• Average depth of frost penetration in inches.

(US Department of Commerce Weather Bureau)
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Footing Shapes

• Footings increase supporting capacity of the
  foundation wall.
• Most houses require footings.
• Soil bearing capacity and weight of house
  determine the size and type of footing.
• Footings are generally poured concrete.
• Footing size is typically based on the foundation
  wall thickness.

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Footing Shapes

• A footing expands load bearing area.

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Footing Shapes

• General proportions of a footing.

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Footing Specifications

• Footing thickness generally equals the foundation
  wall thickness.
• Footing width is twice the wall thickness.
• Poor soil may require wider footings.
• Settling occurs during construction.
• Prevent uneven settling.
• Check code recommendations.
• Use steel reinforcing bars.

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Fireplace and Chimney Footings

• Fireplace and chimney footings are more massive
  than regular house footings.
• Should be reinforced with steel.
• 12 inches thick.
• Extend 6 inches beyond the perimeter of the
  chimney.
• Cast integrally with house footing.

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Stepped Footings

• Stepped footings are necessary when building on
  hilly terrain.
• Steps should be placed horizontally.
• Vertical step height is no more than 3/4 of the
  distance between the steps.
• Steps should be multiples of 8 inches in masonry
  construction.
• Use 1/2" steel bars in footings.

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Stepped Footing

• A stepped footing and foundation wall in masonry
  construction.

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Foundation Walls

• Extend from the first floor to the footing.
• May also be basement walls.
• Variety of materials may be used
• Cast concrete, concrete block, pressure-treated
  wood, and stone or brick.
• Four basic types of foundation walls
• T-foundation, slab foundation, pier and post
  foundation, and wood foundation.

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Foundation Walls

• Foundation wall materials.

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Foundation Walls

• Foundation types.

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T-Foundations

• The T-foundation is the most common type of
  residential foundation.
• Name is derived from the shape.
• Footing and foundation wall are usually separate
  parts.
• Footings are usually cast in forms.
• Variety of applications of T-foundation.

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T-Foundation Application

• 8" foundation wall with insulated slab floor.

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T-Foundation Application

• 8" basement wall and footing.

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T-Foundation Application

• Insulated slab for perimeter heat.

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T-Foundation Application

• 12" concrete block foundation for brick veneer on
  frame.

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T-Foundation Application

• Poured concrete foundation for brick and block
  wall.

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Footing Forms

• Construction boards.

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Footing Forms

• Manufactured forms that stay in place and serve
  as a drain tile.

(CertainTeed Corporation)
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Slab Foundations

• A slab foundation is an extension of a slab
  floor.
• Cast when the floor is placed.
• Sometimes called thickened edge slab.
• Should extend below the frost line.
• Reinforcement is recommended.
• Advantages Requires less time, labor, and
  expense to construct.

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Slab Foundation Application

• Foundation for 10" cavity wall with slab floor.

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Slab Foundation Application

• Foundation for 10" masonry bonded wall with slab
  floor.

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Slab Foundation Application

• Thickened edge slab foundation for frame wall.

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Slab Foundation Application

• 8" bearing wall partition on slab floor.

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Pier and Column Foundations

• Piers and columns are similar.
• Pier foundations sometimes replaceT-foundations
  under the house.
• Piers often used in a long crawl space.
• Columns are used in basements where the span is
  too long.
• The difference between piers and columns is their
  height.
• A column has a footing and post.

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Pier Foundation
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Pier Variations
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Post (Column) Foundation

• A pipe or adjustable jack post is frequently used
  to support a beam. This is a column or post
  foundation.

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Post (Column) Foundation
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Wood Foundations

• Wood foundations are a below-grade,
  pressure-treated, plywood-sheathed stud wall.
• Popular where winter weather stops construction.
• Accepted by HUD, FHA, and FmHA.
• May be used in basement or crawl space
  construction.

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Wood Foundation

• Typical wood foundation with crawl space.

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Wood Foundation

• Typical wood foundation for basement.

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Wood Foundation Construction

• Placing the footing plate.

(Osmose Wood Products)
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Wood Foundation Construction

• Excavation should allow for 2" sand or 6" crushed
  stone for the footing.
• Sand base must be perfectly level and accurately
  located.
• Footing plates are 2" x 8", 2 x 10", or 2" x 12"
  pressure-treated lumber.
• Foundation walls are 2"x 4" or 2" x 6" stud frame.

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Wood Foundation Construction

• Fasteners are silicon, bronze, copper, or
  zinc-coated steel.
• Sheathing is pressure treated plywood.
• All framing lumber is pressure treated.
• Backfill after basement floor has cured and first
  floor is installed.

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Wood Foundation Construction

• Basement walls in place.

(Osmose Wood Products)
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Concrete and Masonry Basement Walls

• Factors influencing strength and stability of a
  basement wall include
• Height and thickness.
• Bond of the mortar in a masonry wall.
• Vertical loading.
• Support from cross walls or pilasters.
• Support from first floor framing.
• Wall thickness depends on lateral earth pressure
  and vertical load.

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Minimum Thickness of Basement Walls
(Portland Cement Association)
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Pilasters

• Pilasters may be used to strengthen basement
  walls.
• Built at the same time as the wall.
• Masonry wall pilasters are usually 8" x 16" in an
  8" thick wall.
• Distance between pilasters should not exceed 15'
  in an 8" wall and 18' in a 10" wall.
• Pilasters are also used to support beams.

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Pilasters
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Wall Stiffeners

• Wall stiffeners provide an alternative to
  pilasters.
• Accomplished by placing a Number 4 bar in one
  core of the block from footing to top plate.
• Another method is horizontal steel joint
  reinforcement at 16" intervals vertically.

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Basement Wall Construction

• Top of wall should be at least 8" above the grade
  in frame construction.
• Wood sills should be anchored to basement wall
  with anchors or clips.
• Provide at least 7'-5" headroom.
• Load bearing cross walls in basement are not
  masonry bonded to entire wall.
• Use tie bars 1/4" by 1-1/4" by 28" long.

(continued)
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Basement Wall Construction

• Anchor clips.

(The Panel Clip Company)
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Basement Wall Construction

• A solid cap is recommended to spread the load
  over the wall.
• Dampproofing required on the outside of the
  basement wall
• Parge coat and sealer.
• Excess ground water removal system may be needed.

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Basement Wall Section
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Water Removal Method

• Drain tile placement.

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Water Removal Method

• Footing forms that serve as drain tiles.

(CertainTeed Corporation)
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Beams and Girders

• Beams or girders support floor joists over long
  spans.
• May be wood or metal.
• Wood beams may be built-up or solid.
• Steel beams may be S-beams orW-beams.
• Size based on weight of the structure and the
  span.

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Typical Steel Beams
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Structure Loads

• Dead load is the weight of the structure itself
• Roofing, siding, joist, etc.
• Live load is the fixed or moving weights
• Furniture, appliances, occupants, snow on the
  roof, etc.

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Weight Supported by Beam
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Load Assumptions

• First Floor and Second Floor
• Live dead load 50 pounds per square foot.
• Ceiling
• Live dead load 30 pounds per square foot.
• Walls
• Dead load 10 pounds per square foot.
• Roof
• No load on beam.

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Weight Calculations Example

• Two Story Frame Structure
• 28' x 40'.
• Area of the House
• 1120 square feet per floor.
• Wall Area
• 320 square foot per wall.
• Assumes a bearing wall on each floor.

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Weight Calculations Example

• Foundation of the house.

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Weight Calculations Example

• Weight of first floor 56,000 lbs.
• Weight of second floor 56,000 lbs.
• Weight of ceiling 33,600 lbs.
• Total weight 145,600 lbs.
• Half bears on the beam 72,800 lbs.
• First and second floor wall weight total 6,400
  lbs.
• Weight bearing on the beam 79,200 lbs.

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Weight Calculations Example

• W-beam span and load table.

(American Institute of Steel Construction)
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Weight Calculations Example

• Length of beam 40 feet.
• Three columns reduce span to 10'-0" and 19.8
  kips(1 kip 1000 pounds).
• An 8" x 6 1/2" WF beam will support 23 kips.

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Weight Calculations Example

• Three supporting posts are added.

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Weight Calculations Example

• Post Selection
• Size is determined by weight to be supported and
  length of post.
• Post must support 26 kips.
• Post length is 8 feet.
• Chart (Figure 11-32 in text) shows that a 3" post
  will support 34 kips.

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Weight Calculations Example

• Weight supported by each post.

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Weight Calculations Example

• Steep pipe columns load table.

(American Institute of Steel Construction)
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Lintels

• A lintel is a horizontal structural member that
  supports the load over an opening.
• Materials
• Precast concrete, cast-in-place concrete, lintel
  blocks, steel angle.
• Bearing surface of steel angle lintel extends
  into the masonry at least 4".

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Types of Lintels
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Precast Lintel

• In a masonry wall.

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Steel Angle Lintel

• In a brick wall.

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Concrete

• Concrete is ordered by the cubic yard.
• One cubic yard is 27 cubic feet.
• A six-bag mix recommended.
• Concrete is composed of cement, sand, large
  aggregate, and water.
• It requires 28 days to fully cure at 70F.

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Concrete Finishing

• A screed used to smooth the surface.
• A float used to embed large aggregate, remove
  imperfections, and consolidate mortar.
• A trowel used to develop a hard, smooth surface.

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Contraction Joints

• Contraction joints are used to minimize and
  control cracking.
• Place in line with interior columns.
• Place at changes in width of slab.
• Maximum spacing of joints is 20 feet.

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Floor Slabs

• A concrete floor slab should be placed on 4" to
  6" of compacted sand.
• Slab thickness is 4" minimum.
• Slabs should not be bonded to footings or
  columns.
• A 1" thick sand cushion may be used to separate
  the slab from the footing.

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Floor Slab Section
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Concrete Blocks

• Used to form exterior and interior walls.
• Variety of sizes and shapes available.
• Hollow concrete masonry units.
• Basic size is 8" x 8" x 16".
• Actual size is 7-5/8" x 7-5/8" x 15-5/8".
• Designed for a 3/8" mortar joint.
• Decorative blocks are available.

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Common Concrete Blocks
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Decorative Concrete Blocks
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Paving

• A rigid paving system is installed on a concrete
  base.
• Use Type M mortar for rigid paving.
• A flexible paving system is installed on
  compacted sand and crushed stone.
• Prevent creep with rigid edge restraint
• Paving units should conform to ASTM C902.
• Use 2-1/4" pavers for driveways.

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Brick Paving
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Flexible Paving System

• Spreading the crushed stone base.

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Flexible Paving System

• Leveling the setting sand bed.

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Flexible Paving System

• Rigid edge restraint prevents creep.

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Flexible Paving System

• The pavers for this driveway turnaround are
  2-1/4" pavers.

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Glossary

• Batter Boards.
• Used to retain the location of the foundation
  during excavation and construction.
• Bearing Wall.
• Designed to support part of the load of the
  structure.
• Cement.
• Composed of a mixture of lime, silica,
  alumina, iron components, and gypsum.
• Concrete.
• The result of combining cement, sand,
  aggregate (usually stone or gravel), and water.

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Glossary

• Contraction Joints.
• Grooves cut into concrete to minimize or control
  cracking due to temperature changes.
• Creep.
• Horizontal movement of a permanent object,
  such as pavers, or concrete slabs.
• Dead Loads.
• 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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Glossary

• Flexible Paving System.
• Consists of a well-compacted subgrade beneath a
  layer of crushed stone, a sand setting bed, and
  fine sand between the pavers.
• Float.
• A short board, about a foot long, with a
  handle attached to one of the flat sides and used
  to embed the large aggregate just beneath the
  surface remove any slight imperfections, lumps,
  and voids to produce a flat surface and
  consolidate mortar at the surface in preparation
  for final steel-troweling.

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Glossary

• Footings.
• Increase the supporting capacity of the
  foundation wall by spreading the load over a
  larger area.
• Kip.
• A unit of weight measurement one kip is one
  thousand pounds.
• Lintel.
• A horizontal structural member that supports
  the load over an opening such as a door or
  window.

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Glossary

• Live Loads.Fixed or moving weights that are not
  a structural part of the house examples include
  furniture, occupants, snow on the roof, wind,
  etc.
• Parge Coat.
• A thin coat of plaster over the foundation
  wall.
• Pier Foundation.
• Consists of piers and footings.
• Post Foundation.
• Consists of columns (posts) and footings.
  Columns are taller than piers.

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Glossary

• Pilaster.A rectangular column that projects from
  a wall also used for additional girder or beam
  support
• Rigid Paving System.
• Consists of a well-compacted subgrade, a
  properly prepared base, a reinforced concrete
  slab, a mortar setting bed, and brick paving with
  mortar joints between the pavers.
• Screed.
• A long straightedge, usually a board, that is
  worked back and forth across the surface to bring
  excess water to the surface and settle the
  aggregate.

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Glossary

• Slab Foundation.An extension of a slab floor it
  is placed at the same time the floor is cast and
  is not a separate unit.
• Stepped Footings.
• Frequently necessary when building on hilly
  terrain.
• T-Foundation.
• The most common type of foundation the name
  is derived from the shape of the foundation and
  footing, which look like an inverted T.

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Glossary

• Trowel.A rectangular tool used in a circular
  motion to further harden the surface of concrete
  and develop a very smooth finish.
• Wood Foundations.
• A below grade, plywood-sheathed,
  pressure-treated stud wall known by several
  names permanent wood foundation (PWF),
  all-weather wood foundation (AWWF), and treated
  wood foundation.

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Glossary

• 9-12-15 Unit Method.
• These proportions define a right triangle and
  establish a 90 degree angle corner. Measure 9
  units along one leg of the corner and 12 units
  along the other leg. The distance between these
  two endpoints should be 15 units. Adjust the legs
  of the angle until the distance is exactly 15
  units.