Conventional Basement Construction Methods

Local Issues

• Basement construction methods depend heavily upon where you live. Local building codes set minimum basement headroom clearance -- often seven feet. If the basement will contain future bedrooms, code requires egress windows, which allow a person to escape in the event of a fire. When adding egress windows, window wells are necessary. Basement walls require the installation of steel reinforcement. How much you must add depends on local codes, and a building inspector will check before you pour concrete to ensure that you’ve added enough steel.

Preliminary Work

• Before you excavate, it’s customary to stake out the location of the future basement walls and the elevation of the top of the basement. Subdivision rules set the elevation restrictions to ensure uniformity of style in the neighborhood, and to reduce drainage problems caused by some homes sitting higher than others do. Before issuing a permit, local building authorities usually require a set of blueprints for their files, and the plans for the home must meet aesthetic and safe building codes.

Poured vs. Block Basement

• The two main types of basements are poured concrete and concrete block. Both types offer structurally sound foundations. It's simpler to construct a block basement where access to the job site doesn’t permit concrete trucks close enough to pour. In soils that are stable, such as sandy or rocky soils, you can probably install a block foundation. In other areas where the soil contains clay, building codes may not allow block foundations due to the increased risk of soil movement. Poured concrete typically resists leaks better than blocks, but both foundations benefit from exterior waterproofing.

Best Practices

• Conventional basements sit on footings that are three or four times the width of the basement wall to stabilize the basement and transfer the weight load to the ground. To prevent future water problems, it’s best to install perimeter drain tile at the footer level before back-filling. Drain tile requires the installation of a sump pump, below footing level, that collects perimeter water and pumps it to the surface of the ground, when necessary.