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Building Foundations. Foundation Walls. A base Monolithic construction Independent construction. Footings. Spread footings Undisturbed soil. Foundation-Wall Footings. Prevent settling or cracks Minimum of 12” below grade. Below frost line Thickness = thickness of foundation wall

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building foundations

Building Foundations

Foundation Walls

footings
A base

Monolithic construction

Independent construction

Footings
footing design
Prevent settling or cracks

Minimum of 12” below grade. Below frost line

Thickness = thickness of foundation wall

Width = 2x thickness of foundation wall

Footing Design
footing reinforcement
Rebar embedded

2 lengths of ½” diameter (#4) rebar

Positioned minimum of 3” above bottom

Footing Reinforcement
footing forms
Form

steel, lumber, or combination of lumber & plywood.

Keyway

Footing Forms
footing drains
4” diameter pipes at base of footing

Carries water away from house.

Sloped at least 1/8” per foot

Landscaping Fabric

Footing Drains
poured concrete foundation walls
Durable & water resistant

Most building sites

Support any type of house

8 –10” thick

Min. compressive strength 2500 psi

Most 8’ high

Poured-Concrete Foundation Walls
full height walls
Formwork

Reusable forms

Wales

Full Height Walls
standard wall forms
Wood or metal

Built on site

Prefabricated forms

Snap-ties

3 –7 days

Standard Wall Forms
insulating wall forms
ICFs (Insulating Concrete Forms)

Permanent

Basic components

planks, sheets, or hollow blocks

Standard wall

Grid wall

Insulating Wall Forms
placement
Poured continuously without interruption

Cold joint

Water content

Remove Air pockets

Concrete vibrator (stinger)

Placement
crawl space walls
Advantage – reduced cost

Soil cover

Ventilated

Insulated

Piers support

Crawl-space Walls
sill plate anchors
Anchor bolts

Metal strap anchors

Sill sealer

Sill Plate Anchors
foundation wall details
Special features:

Brick-veneer siding

Utility Sleeves

Foundation Wall Details
foundation vents and windows
Metal vents

Rust-resistant steel frame windows

Wood framing (pressure treated)

Foundation Vents And Windows
stripping and maintaining forms
Wood wedges (no metal pry bars)

Stiff bristle (not wire) brush

Form-release agent – Bio-slick

Stripping and Maintaining Forms
moisture protection
Bituminous (tar) coating

Top of footings to finished grade level

Moisture Protection
backfilling
Filling in excavation area

Too soon, push in foundation walls

First floor framing

Temporary bracing

Backfilling
concrete block walls
Popular for foundation walls

No formwork

Blocks inexpensive

Work stopped and started

Concrete Block Walls
concrete block basics
Concrete Masonry Unit (CMU)

Head Joint

Bed Joint

Common bond

Pilasters

Protect from freezing & moisture

Concrete Block Basics
mortar
Mortar bond strength depends on:

Type & quantity

Workability, or plasticity

Surface texture bedding areas

Rate at which masonry units absorb moisture from mortar

Water retention

Skill of person laying block

Mortar
mortar mixtures
Portland cement, hydrated lime, sand, & water.

Prepackaged mortar mix

Type N

Type M

Type S

Type O

Mortar Mixtures
mixing and placing mortar
Evaporation

Hydration

2 ½ hour when air temp is 80ºF or higher

3 ½ hours when air temp is below 80ºF.

Mixing and Placing Mortar
laying block foundation walls
Skilled masons

Corners built first

Story pole (course pole)

Laying Block Foundation Walls
tooling the joints
Weather tight joints & neat block walls

“Thumbprint hard”

Tooling compacts

Head joints, then bed joints

Tooling the Joints
radon
Colorless & odorless radioactive gas

Extremely toxic

Lung cancer

Soluble in water

9X heavier than air

Radon
radon resistant construction
Gas-permeable layer

Soil-gas retarder

Sealants

Vent pipe

Cap course

Radon-Resistant Construction
review
Review
  • What is the minimum depth required for an exterior-wall footing?
  • Describe the type and position of reinforcement that is commonly added to strengthen a footing.
  • What is a keyway and how is it formed?
  • For nearly all poured-concrete foundation walls, formwork must be constructed for each wall face. What holds the formwork together?
  • What creates a cold joint?
  • Why are the joints in a concrete block wall tooled?
  • When using mortar, why is it helpful to know the differences between hydration and evaporation?