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FOUNDATIONS Slide 2 Components Footings Trench Formed Keyway Stepped Fireplace Slide 3 Foundation Concrete support for floor framing & rest of the house Slide 4 ACCURACY & QUALITY KEY! *Soil quality effects type of foundation used Foundation: Carry Loads Distribute weight to soil evenly Footing spreads the weight Resists forces wind/earth (by anchoring down walls / eaves) Material: Concrete (works in compression) and Steel rebar (works in tension to resist min. earth movement) Slide 5 Compression is a pushing force Tension is a pulling force Slide 6 Slide 7 Requirements for footings Rest on Undisturbed soil Lie below the frost line (in colder climates) Washington Country 12 Multnomah County 18 Check your local code Slab on grade used in warmer climates Footing width depends on soil type and # of stories Slide 8 Soil Bearing Capacity Class of MaterialsLoad Bearing Pressure Crystalline Bedrock12000psf Sedimentary and Foliated rock4000psf Sandy Gravel3000psf Clay, Sandy Clay, Silty Clay,1500psf Slide 9 Footing Widths Examples: Soil bearing capacity 1000 psf +1 story= 18 Footing Soil bearing capacity 3000 psf +1 story= 12 Soil bearing capacity 1000 psf +3 story= 27 Soil bearing capacity 3000 psf +3 story= 12 Slide 10 Footing Widths LOAD BEARING VALUE OF SOIL (psf) 1000150020003000 Conventional Light-Frame Construction 1-Story1812 2-Story231512 3-Story27181412 4 brick veneer over light frame or 8 hollow concrete masonry 1-Story231512 2-Story29191312 3-Story35231612 8 solid concrete or masonry, or fully grouted masonry 1-Story26171312 2-Story36231812 3-Story45302316 Slide 11 More Footing Requirements Horizontal Rebar per local code Vertical Rebar per local code Must project at least 2 beyond wall A means of connection to wall Keyway Rebar Slide 12 KEYWAY Slide 13 Types of Footings Slide 14 STEP FOOTINGS Slide 15 Slabs Block Outs and penetrations designated by an X Control Joints - control cracks (every 20) Expansion joint where vertical wall and slab meet allows for movement due to expansion and contraction. Slide 16 Slide 17 Slide 18 Slide 19 Reinforcing Bar (Rebar) Measured in 8ths Example: #4 Rebar = 4/8 or diameter #3 rebar = 3/8 diameter Slide 20 3 Types of Residential Foundations 1.Crawl space 2.Basement (full or partial) 3.Slab on Grade Alternative FND. Pole / Pilings (when soil not good) Slide 21 Crawl Space 18 minimum height from ground to bottom of floor joist Slide 22 Crawl Space Slide 23 Basement Wall Slide 24 Stem Wall Slide 25 Slab On Grade Slide 26 Slide 27 Abbreviations & Terms WWM = welded wire mesh WWF = welded wire fabric Slide 28 Step Footing Slide 29 YOUR TURN Slide 30