![]() With the pitted surface, there is less concrete surrounding the steel rebar, and corrosion can occur at a faster pace. The presence of honeycombing usually means that while it was still wet, the concrete wasn’t vibrated enough to fill the voids, or the mix of aggregates doesn’t have enough fines (sand or small aggregate) to fill the spaces between larger pieces of rock. Honeycombing-this is when the finished concrete surface has many pits instead of a smooth surface.Over time, the corrosion builds up or migrates, the cracks spread larger, and the concrete will eventually fall off in pieces, exposing the rebar. The first indicator that you may have a corrosion problem is efflorescence, indicating that there is water intrusion, followed by brown rust-colored cracks. The chemical reaction of corrosion deteriorates and breaks down the steel material, so over time, the strength of the foundation decreases. Corrosion-this occurs when water has seeped into the concrete foundation so persistently that it causes corrosion (rust) in the steel rebar.Over time, water exposure will weaken the concrete foundation. Therefore, you may need better drainage around your house. If the foundation is years old and the white residue has increased, then rainwater could be seeping into the foundation. It’s common to see some white color directly after curing. As the water in the concrete mixture begins to evaporate, it brings calcium salts with it to the surface. Efflorescence can occur with new concrete during the curing process. Efflorescence-this is when you can see white spots and white trails on the concrete.So, what should you look for when looking at a reinforced concrete foundation? Both these types of foundations will sustain disproportionate damage from earthquake shaking. Even worse are foundations made of bricks only, without steel or concrete. Unfortunately, some older homes may have foundations made of concrete only, with no reinforcement. Concrete withstands compression (pushing forces), and steel resists tension (pulling forces), so the combination of concrete with steel rebar makes the perfect marriage to deal with the compression and tension forces from the weight of a building. ![]() The addition of steel bars (“rebar”) makes it reinforced concrete. ![]() The shared element of the three common types of foundations is concrete.Ĭoncrete is a mix of crushed rock ( aggregate), cement, water, and air. Older homes typically have a (sometimes reinforced) concrete perimeter foundation, and newer construction usually has a reinforced concrete slab foundation or a post-tensioned concrete slab foundation. The three most common types of foundations for houses in California are reinforced concrete perimeter foundation with crawl space, reinforced concrete stem wall foundation, and reinforced concrete slab foundation-see the image below. When the ground shakes, and your foundation moves with it, will your foundation be damaged? What Type of Foundation Do I Have? The foundation is a vital connection point, which affects how your house will fare in an earthquake. ![]() The foundation of your house or condo building supports the weight of your home and anchors it to the ground. When you remodel your house or condo building, you might find yourself with a decision: should I update the kitchen or replace the foundation, or both? Most of us don’t see the concrete foundation every day, so when you do take a look you might wonder: is that normal? Let’s peek “under the house” to learn more!
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