FRAMING SEMINARS 2012 PRESENTED BY KW ENGINEERING 1

The Instructor – Who am I  Ken Watters II, P.E. 42 years old Penn State Graduate.  Currently registered structural engineer in 8 states.  I have appeared as an expert witness in both truss and code related court cases.  25+ years of experience in construction.  Much of my experience has come hands on in the field.  I am a practicing engineer with my own small firm.  Offices in PA and CO.  Love the mountains and the outdoors.  Avid Downhill and Backcountry Skier. 2

3 Engineering design from Mountain Top to Coast. East Coast 2053 West Woodbine Rd. Airville, PA Rocky Mountains P.O. Box Platte River Dr. Fairplay, CO 80440

4 IRC International Residential Code

5 Outline  Prescriptive Foundation Design Per IRC 2009  Existing and new practices that are outside the scope of the IRC are permitted as an engineered design.

6 Today’s Homes & IRC Scope  Wood Framed Buildings  ≤ 36 ft. in width  ≤ 60 ft. in length  ≤ 3 stories above grade in height  3:12 ≤ roof slopes ≤ 12:12  Portions of structures outside these geometry limitations are outside the scope of the IRC  Expected to be designed by an architect or engineer

7 Today’s Homes & IRC Scope  Restricted to buildings within stated regions:  Basic wind speeds less than 100 mph in hurricane-prone regions, or less than 110 mph elsewhere  Ground snow load is 70 psf or less  Special requirements are included for regions having a seismic design category designation of C, D 0, D 1, or D 2  Portions of structures outside these geometry limitations are outside the scope of the IRC  Expected to be designed by an architect or engineer  IRC’s code provisions may be inadequate, misunderstood or misapplied.

Common issues outside the scope of the IRC 8  Buildings with Steel Beams  Foundation walls laterally unsupported at the top (>4’ tall)  Tall walls over 12’  Discontinuous wall foundations  Floor systems deeper than 16”

9 Overview of Issues  A little of what not to do! Courtesy Aries Engineering

Continuous Foundations  Can a wall footer that requires a step due to grade conditions be discontinuous? 10

Inside of crawl space 11

Close-up 12 Top of higher footer Top of lower footer 2x Wood “Bridge”

R403.1 General. All exterior walls shall be supported on continuous solid or fully grouted masonry or concrete footings, crushed stone footings, wood foundations, or other approved structural systems which shall be of sufficient design to accommodate all loads according to Section R301 and to transmit the resulting loads to the soil within the limitations as determined from the character of the soil. Footings shall be supported on undisturbed natural soils or engineered fill. Concrete footing shall be designed and constructed in accordance with the provisions of Section R403 or in accordance with ACI

R Slope. The top surface of footings shall be level. The bottom surface of footings shall not have a slope exceeding one unit vertical in 10 units horizontal (10-percent slope). Footings shall be stepped where it is necessary to change the elevation of the top surface of the footings or where the slope of the bottom surface of the footings will exceed one unit vertical in ten units horizontal (10-percent slope). 14

Figure R

Foundation depth R Minimum depth. All exterior footings shall be placed at least 12 inches (305 mm) below the undisturbed ground surface. Where applicable, the depth of footings shall also conform to Sections R through R Inside and Outside of the building for Exterior Footings? What is the definition of Undisturbed Ground Surface? Is this the height or grade of the ground before excavation or after construction and backfilling are complete?

Exposed Crawl Space Footing 17 Bottom of footing

Lateral Wall Support 18 R Design required. Concrete or masonry foundation walls shall be designed in accordance with accepted engineering practice when either of the following conditions exists: 1. Walls are subject to hydrostatic pressure from groundwater. 2. Walls supporting more than 48 inches (1219 mm) of unbalanced backfill that do not have permanent lateral support at the top or bottom.

Lateral Wall Support  What constitutes lateral support for the top and bottom of the wall 19

Lateral Wall Support  Bottom of wall  Slab most common  How much Dirt or stone would you need? Passive vs. Active pressures 20

Lateral Wall Support  Top of wall  Less force than the bottom  Often wood sill plate supported by floor joist and subfloor.  Can an end joist by itself support the top of a foundation wall? 21

Lateral Wall Support 22

23 PRESENTED BY KW Engineering Web: kweng.net KEN WATTERS II, P.E