Can You Lower a Pier & Beam Foundation?

Design

• Pier and beam foundations are built using columns, or piers, that are submerged below the ground. Pier depth is determined by the frost line, and optimum pier height depends on the quality of soil. Piers must be drilled and placed below the frost line to avoid heaving and instability. They must extend above the soil to heights within a minimum of 12 inches to allow for ground clearance, especially that of expansive soils. Expansive soils have a greater rate of flux than nonexpansive soils. When expansive soils are frozen, dry or wet, their volume either increases or decreases. The increase or decrease in volume causes the ground level to change. Floors that are placed above low piers will sustain damage from ground pressure.

Benefits and Drawbacks

• Pier and beam foundations are designed in such a way that the home sits on top of strategically spaced piers and creates a crawlspace. This crawlspace is beneficial when maintenance needs to be made on wires and plumbing sited below the home's floor. Crawlspaces can become problematic when moisture collects beneath the floor or when the space is not properly insulated. Lowering the foundation will not solve these problems. Instead, ensure that adequate ventilation and insulation are put in place during construction.

Ventilation and Insulation

• Keep the foundation ventilated by planting trees and flowers away from the foundation. Do not block the foundation crawlspace with snow or other debris. Well-ventilated crawlspaces prevent moisture from building up in the space. Moisture can cause wooden piers, beams and joists to rot. Mold can contaminate underflooring. Leave a space of 16 inches between the floorboards and the main floor support beam as a way to ensure proper circulation between the home floor and the crawlspace. Insulation is installed around the exposed portions of piers and along flooring and beams. Insulation helps keep the home warm but also helps keep the ground beneath the home warm. Warm ground is less likely to heave and cause damage.

Considerations

• Pier posts can be made of poured concrete or from pressure-treated wood. Homes built on pressure-treated wood can be prone to termite infestation as well as rots and molds. Avoid using wood in areas prone to flooding or other wet conditions.