Roof Terms

• Span– Distance across the building

Roof Terms

• Run– 1/2 the distance across the building (1/2

span distance)

Roof Terms

• Rise– The distance the roof rises (distance from

the square of house to ridge)

Calculating Roof Surface

• Calculate horizontal area• Determine slope factor (ratio between run and

hypotenuse of the roof pitch

• Multiply slope factor times horizontal area.

4

75 feet

35 feet

12

5

FOUNDATIONS

5

FoundationsLuke 6: 48-49

48. “He is like a man building a house, who dug deep and laid the foundation on the rock. And when the flood arose, the stream beat vehemently against that house, and could not shake it, for it was founded on the rock.”

49. “But he who heard and did nothing is like a man who built a house on the earth without a foundation, against which the stream beat vehemently; and immediately it fell. And the ruin of that house was great.”

FOUNDATION FAILURES STAND OUT

7

3 BASIC REQUIREMENTSA foundation must:

• Not be susceptible to collapse,• Not allow settlement to occur which

results in damage or failure of the superstructure to function as it should, and

• Be feasible and buildable without affecting surroundings.

8

Foundation Design Factors

• Loads & Pressures• Soil• Climatological and water control (Frost,

drainage, etc.)

Loads & Pressures

• Foundation walls must be strong enough to resist applied loads

FOUNDATION LOADS

• Dead loads• Live loads• Wind loads• Other horizontal loads (?)• Buoyant loads• Earthquake (seismic) loads

11

SOIL TYPESROCK

SOILBOULDERS

COBBLES

GRAVEL

SAND

SILT

CLAY

12

Soil Types Bearing Capacity

• Rock 4000 psi or 20% (crushing value)• Gravel 2000• Sand

– Course 1500– Fine 1000

• Clay– Hard 3000– Sandy 2000– Soft 1000

• Adobe 1000• Silt 500

Bearing capacity of the soil depends on soil composition and moisture content

Climate Considerations

• Moisture/Water Content– permeability of soil--water absorbed into soil

causes expansion, thus causing the foundation to heave

• Surface and ground water must have proper drainage– Codes require finish grade to slope away from the

foundation at minimum slopes: • planted--1/2”/12” 6 foot away from building• paved areas--1% slope

Climate Considerations

• Freezing– Water expands as it freezes– Expansion and shrinking of the soil causes

heaving in the foundation– General depth requirement/guideline

• 12” below average frost depth

– Design for sizing footing is determined by the calculations done by the architect or engineer considering loads and soil conditions or using code, depth may follow the rule given above

Climate ConditionsFrost Depth Chart

FOUNDATION SELECTION

PRIMARY• SUBSURFACE AND GROUND WATER• STRUCTURAL REQUIREMENTS

SECONDARY• CONSTRUCTION METHODS• ENVIRONMENT• CODES / REGULATIONS• IMPACTON NEARBY FACILITIES• TIME AVAILABLE FOR CONSTRUCTION• CONSTRUCTION RISKS

17

TYPES OF FOUNDATIONSDEEP

• CAISSONS• PILES

SHALLOW• COLUMN FOOTINGS• WALL FOOTINGS• SLAB ON GRADE• MATS• FLOATING

18

Pilings• Cast-in-Place

concrete piling shapes

• Steel Piling Detail Drawing

Caisson Rebar Cage

20http://www.azarbuilders.com/gallery/caisson1.jpg

COLUMN / WALL FOOTINGS

21

Pier Foundations• Pier foundation resemble pedestal

foundations• Pier Foundation Drawing Representations

Grade Beams• Replaces footings

in unstable soil• Grade beam

becomes an actual beam support by pilings or large pier footings

Mat Foundation

24http://www.irvinegeotech.com/projects.htm

Stepped Foundation

Most Codes give limits:

• Height of step = 24” maximum

• Run of step = 32” minimum

Slab or Monolithic Foundations

• On-Grade Slabs-- called Monolithic if foundation and slab are poured together

• One Placement Two Placements

Foundation Reinforcement

• Concrete & Masonry Resists Compressive Forces

• Concrete & Masonry lousy in resisting Tensile Forces

Foundation Wall Reinforcement

• Reinforcing Bar (Rebar) is placed in the foundation wall to resist possible lateral and bending forces.

Footing Reinforcement

• When the footing is placed near conditions of expansive soil, the bottom of the footing will bend, placing the footing in tension.

• Steel reinforcement is placed in the bottom of the footing to resist the forces of tension in concrete.

• The distance from the bottom of the footing:– Cover varies (1 ½” to 3” coverage) depends on size of

reinforcement and exposure conditions. (formed, not formed, in contact with soil or not, environment, etc.)

Slab Reinforcement

• WWF is used to help the slab resist cracking

• Also placed near the surface in grid patterns to help resist tension in bending

• Steel rebar can also be used to prevent bending of the slab due to beam action in the slab

31

SETTLEMENT

• UNIFORM SETTLEMENT• DIFFERENTIAL SETTLEMENT

32