Protect Your Home: Build a Strong Foundation

05/03/2023

Why do they matter?

Strong foundations help stabilize your house during earthquakes, floods, high winds, hurricanes, and tornadoes. They resist hydrostatic forces of water, carry wind forces down to the ground, and resist seismic forces as they pass underneath your home. A house with strong wall-to-foundation anchorage and connections will help prevent your home from collapsing, moving, sinking, sliding, tipping, or overturning during disasters.

A strong home foundation is one of the essential parts of your resilient home. 

What do I need to know?

House design, budget, climate, location, soil conditions, and moisture are the main factors used when selecting a foundation type for your home. Three main types of foundations are commonly used for residential and single-family homes.

• Poured concrete or “slab-on-grade” foundations are the most common type used for houses, especially in climates that do not experience winter freezes. This foundation is constructed by pouring concrete into a steel-reinforced mold on a framed gravel bed. You can adapt this foundation for use in colder climates with insulation and by adding concrete footings that extend into the ground below the expected frost line.
• Permanent wood foundations are less common than poured concrete but offer lightweight, high-strength, durable options for home construction. These foundations are constructed using treated, moisture-and decay-resistant lumber or engineered wood. The advantages of this type of foundation are that they are simple to build, insulate, and weatherproof. The disadvantage may be that this foundation cannot handle the heaviest loads.

• Raised Foundations are common along the coast and in flood-prone regions, as they can support the home while resisting moisture conditions. There are two main types of raised foundations, stem wall and pier-and-beam. Note: Pier-and-beam is sometimes called post-and-beam, but generally, pier refers to concrete, and post refers to wood.

A house with a stem wall foundation has a wood-framed first floor attached to a raised concrete perimeter made from reinforced masonry (CMU or cinder blocks.) A pier-and-beam foundation is a system of vertical pillars or piers extended into the ground on footers. The piers support the joist system that holds up your home’s floor.

Retrofitting wood and raised foundations to strengthen their performance in disasters is cost-effective and relatively simple. Retrofitting poured concrete foundations may be more costly as it could require some drywall removal to create access.

Where do I start?

• Consult a contractor or professional engineer whether designing a foundation for your new home or retrofitting an existing home. However, some retrofitting grant programs provide pre-approved plans with prescribed strengthening and anchoring methods.

More Resources:

FLASH. Resilient Design Guide: High Wind Wood Frame Construction Edition

FLASH. Resilient Design Guide: Concrete Construction Edition