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J. Edward Sauter, NCARBExecutive Director, Concrete Foundations Association
What to do WhenYour Foundation
Contractor isGone?
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Resources ACI 332-04 (American Concrete Inst) CFA Standard (Concrete Fndn Assoc) IRC (International Residential Code) Residential Foundations (NAHB)
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WhyBuild aBasement?
Frost Protection
Security and Safety
More Living Space
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Foundation System Soil Concrete Footing Vertical Wall System
Wall (Reinforced or Plain) Top Restraint Bottom Restraint
Backfill Water Protection
Waterproofing/Dampproofing Drainage System Site Drainage
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What is Concrete?
Portland Cement Water Large Aggregate Small Aggregate
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Characteristics of Concrete
It Gets Hard and It Cracks Weight +/- 150 # Cubic Foot Compressive Strength = 2500 - 5000 psi Tensile Strength (MOR) = 300 to 500 psi Measured by the Cubic Yard
(1 CY = 5 lf of 8”x 8’-0”wall)
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Curing Concrete
Needs Three Conditions to CureMoistureTimeTemperature
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Impact of Adding Water
Lower strength (200 psi/Gallon of Water) Higher permeability Decreased resistance to weathering Poorer bond between concrete and reinforcement Increased drying shrinkage and cracking Greater volume change from wetting and drying
Harming Concrete
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Spread Footings
Side FormsLateral Restraint
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Foundation Wall Simply Supported
Top and Bottom Transfer of Vertical
Load to Footing Vertical Flexural
Member (ResistLateral Loads)
Extend FoundationBelow Frost Depth
Enclose Lower LevelSpace
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Reinforcement Plain Structural
Concrete WallTemperature & Shrinkage(3 horizontal in 8’)(4 horizontals above 8’)
Reinforced ConcreteWallTemperature & Shrinkageplus StructuralReinforcement(vertical, inside face of wall)
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ACI Empirical Wall Table
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Bottom Restraint Dowel Rod Keyway Basement Slab
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Top Restraint Anchor Bolt Plate Joists Deck
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Anchor Strap Installation
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RCFs(Removable Concrete Forms)
Designed for Production
The entirefoundation istypically installedon a three-dayconstructioncycle!
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Foundation Cycle - Day 1
Footings are Cast
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Foundation Cycle - Day 2
Wall Forming
The sturdy formsare set in place oneside of the wall at atime.
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Foundation Cycle - Day 2
The Wall is CastA local ready-mixtruck brings qualitydesigned concrete tothe job site forplacement.
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Foundation Cycle - Day 3
Forms are Removed
Preparing the wall for….
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The Drainage (Sub) System
Drain Tile Membrane Backfill Material Finish Grading
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DampproofingWill not span discontinuities (cracks)
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Waterproofing
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BackfillingConcrete Reaches Sufficient Strength (7 days) Top and Bottom Bracing is in Place Suitable Backfill Material
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Braced Foundation Wall
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No Top Restraint?
Backfill at Corners Only Backfill to 4’ Length (IRC) Short Wall Segments (8’-12’) Counterforts Temporary Bracing
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Finish Grading (IRC) 6” in First 10 (after settlement) 6” Below Top
of Concrete
4”@Masonry Veneer
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Cracks
Temperature Change Shrinkage Water Pressure Vehiclular Loads Pour Lines Settlement
Why Does Concrete Crack?
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Cracks
Lower Water Content Steel Reinforcement Construction Joints
Methods of Minimizing Cracks
Leaking Displacement Bowing of Wall Width > 1/8”
When is a Crack a Concern?
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Cracks
Surface Drainage Drainage System Waterproofing Epoxy Injection Structural Modifications
Crack Impact Mitigation