A home inspection is an important part of buying a house. For the buyer, an inspection provides valuable information about the condition of the home, and serious foundation issues can ruin a sale.
The purpose of a foundation inspection is to determine if the base of the home is structurally sound. Structural issues can lead to sagging roofs, slanted floors, and cracks that leave the home vulnerable to pests and water damage.
Factors That Contribute to Foundation Problems
A home’s foundation can be damaged by environmental changes like earthquakes, extreme temperatures, and tree roots. If you want to read more about trees and how they can affect foundation, you can check out our blog post here. Other contributing factors are:
- Most lots will have some amount of fill dirt, because the majority of the lots that homes are built on aren’t level and need to be properly graded. Low areas need to be built up with fill dirt, and if the slope of the lot isn’t sufficient, retaining walls will be required to hold the fill dirt. This is because the areas that have fill dirt don’t get compacted as well as they should, and that can compress over time leading to settlement. When foundation soil experiences an extreme change in moisture content, this can result in damage to the foundation in the form of settlement. An excess amount of moisture is capable of saturating the soil of the foundation, which can lead to a softening or weakening of the soil. When the soil is no longer capable of supporting the load, the result is often settlement of the foundation. Different soil types are affected by moisture in different ways.
- Sandy soils. Sandy soils are more predictable, because water passes through rather than being absorbed. Instead of expanding and contracting as they absorb moisture and dry out, respectively, sandy soils are fairly consistent in volume and density. They rarely cause foundation problems because they are less likely to shift and settle, giving them stability and good load-bearing qualities.
- Clay soils. Soils that are rich in clay and silt have the greatest potential to damage a foundation. Clay easily absorbs water, which causes it to expand in volume as it becomes more saturated. Clay soil causes foundations to crack, heave, and shift. When clay soils dry out, they shrink and crack, which leaves gaps around a house where water can easily penetrate and repeat the expansion cycle. Clay soils typically cause more foundation damage by expanding rather than contracting.
- Sandy loam soils. Loamy soils tend to be a very stable soil that shows little change with the increase or decrease of moisture. The biggest concern with foundations built on loamy soils is erosion, because when soils underneath the foundation erode, they are less able to sustain the weight of a foundation.
- Home Age. This might seem obvious, but the age of the home affects the foundation as well. Foundation strength relies a lot on the size and amount of beams present. Older foundations tend to have smaller and fewer beams, making them less stable than homes built today. Today’s homes typically have larger and more beams present, adding stability.
- Poor Drainage. Moisture can be a serious problem for homes in general, but it’s worse when it comes to foundation. Poor drainage will affect the foundation because when water collects around a house, the saturated soil around the foundation expands and shifts. That pressure on the foundation walls increases and results in cracks and leaks that allow water to penetrate the foundation. This is bad for a number of reasons, but it can cause electrical hazards, mold growth, and structural damage. Older homes tend to be built on flat areas where drainage is an issue.
Inspecting the Foundation
When home inspectors get to the foundation portion of the home inspection, you’ll be looking for things like foundation cracks, uneven levels, and damaged walls and floors. If there is a crawlspace under the house, you’ll have to carefully examine it to determine if it’s wet or musty. If there are wet or rotten areas, there may be a foundation drainage problem that needs to be corrected.
Small cracks in the concrete (like the size of thread) can be considered normal, but larger and visibly deep cracks are signs of a bigger problem, and you may need to recommend that a structural engineer come in and do a thorough inspection of the foundation. It’s important to remember that you can’t diagnose foundation issues, you can only report on what you saw during the inspection. It’s ultimately up to the home buyer to decide if they want to bring in an expert (or the seller, if they’re having an inspection done before they list the home).
Ultimately what you’re looking for, whether it’s in a basement or a crawlspace, is that there are no large cracks and everything is dry.
When you’re inspecting the exterior of the home, you’ll also be looking for drainage issues around the home. If there is standing water right next to the foundation, there may be issues inside as well. Poor drainage can be caused by improper grading, or gutters that are clogged or drain too close to the house, just to name a couple. If there is standing water outside of the home, you’ll want to be sure to take a closer look once you’re inside the home to ensure that the foundation is dry.
Other Signs of a Foundation Issue
- Small cracks in the exterior walls or stairs are usually nothing to worry about, but larger cracks or cracks that have a zig-zag pattern can be signs of foundation issues.
- Doors that are no longer square and have cracks in the wall above them are another sign that there may be foundation issues. Homes settle over the years, but cracks above doors are usually a sign of more than just a house settling.
- Uneven floors can also be a dead giveaway of a structural issue. If you can visibly see that the floor is slanted, that’s a red flag. If water spills on the floor or you drop something and it rolls one direction, that’s another bad sign.
There will likely be other issues you run into during your home inspection career, but these are some of the most common issues you’ll find when you’re inspecting a foundation. Most of the time you aren’t going to run into any serious foundation issues, but there may be times where you do, so it’s important to understand what to look for and what may be causing it.
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