FOUNDATION CONSTRUCTION

Concrete Strength

Concrete in Foundation Walls and Footings Not Exposed to Weather

1. Use at least () 2,500 psi concrete in all weathering potential environments. Read the full Topic

Crawl Spaces

Crawl Space Ventilated to Exterior

1. Provide at least () one square foot of net free ventilation area for every 150 square feet of crawl space floor in a ventilated crawl space. You may reduce the net free ventilation area to at least () one square foot for every 1,500 square feet of crawl space floor if you cover the floor with a vapor retarder such as 6-mil polyethylene. Read the full Topic

Exterior Surface Drainage and Gutters

Drainage Near Home

1. Direct surface water away from the foundation to a storm sewer or other approved collection point. Read the full Topic

Footings

Soil Load Bearing Capacities

1. Place footings on undisturbed soil of known bearing capacity or on fill approved by an engineer. Read the full Topic

Foundation and Retaining Walls

Limitations of the Material in this Section

The IRC provides complex rules governing the design of and the lateral support of foundation walls. We do not recommend that readers of this book attempt to design or build foundation walls. Consult a qualified contractor or engineer regarding foundation walls. Refer to the IRC Commentary for more information about foundation wall construction. Read the full Topic

Foundation Drains and Dampproofing

Dampproofing and Waterproofing Definitions

Dampproofing: Dampproofing inhibits the flow of water vapor and small quantities of liquid water under slight pressure through a foundation wall.

Waterproofing: Waterproofing inhibits the flow of water vapor and larger quantities of liquid water under higher pressure through a foundation wall. Read the full Topic

Masonry

Isolated Masonry Piers

1. You may use hollow core concrete masonry units (concrete blocks) to build isolated masonry piers if the units are at least () 8 inches thick and not longer than () 3 times the unit thickness. An isolated masonry pier may not support a floor girder or beam. Read the full Topic