There is nothing sexy about a foundation. Nobody ever cuts their monthly mortgage check and says to themselves, “boy, that’s a lot of money but it sure is worth it to live on top of such a great foundation.”
However, it is not an understatement to say that the entire investment that is your house rests on the foundation. Choose a house with a bad foundation and you have selected a house that has bad bones. Foundation repairs are expensive and can become a home owner’s nightmare. So, understanding a few rudiments of foundations is a great place to start learning about how to look for and select a house to buy.
1. Foundation Materials
Foundations can be built from a variety of different materials. The most common is poured concrete. Depending on where you are looking for a house, you might also find homes built from masonry block, brick, stone, metal pilings or wood (often called post and pier).
The materials used to build foundations will change regionally and with age: older homes are more likely to employ wood and stones and brick and more rudimentary materials than modern foundations, which are usually built from poured concrete.
As a general rule, older foundations are not as strong or well-built as newer foundations.
A smart home shopper will learn about the types of foundations commonly installed in the region in which they’re shopping for a home. If earthquakes are a concern, foundation materials can become paramount to your purchase decision as older foundations such as masonry are less likely to withstand the destructive forces of an earthquake.
The descending sequence below shows a finger-to-the-wind guide for the relative strength of different foundation materials with 1 being the strongest:
- Modern Poured Concrete
- Older Poured Concrete
- Masonry Block
- Brick and Stone (masonry)
- Wood or post and pier
2. Foundation Configurations
When you are looking at a house, it is important to understand that foundations generally come in three different configurations. A house can be built with:
- A basement below the house
- A crawl space below the house or…
- A slab on grade foundation – where the floor of the house is concrete on the ground.
Some houses may even have a combination of all three configurations. A house might have, for example, an old original part that has a basement, an addition for a kitchen that has a crawl space below the floor system and a garage that is a slab of concrete on the ground (slab on grade).
A smart home shopper will be aware of the foundation configurations of the houses they are looking at and have a rudimentary understanding of the various advantages and drawbacks. More on this can be found in my book, “The Confident House Hunter.”
3. Critical Background for Thinking about Foundations
Whether you realize it or not, a lot of thought should go into the type of foundation a house is built on. The guiding engineering factors that dictate most decision making are local weather and soil conditions. Below is a list of some interesting things to consider about foundations and local climate conditions.
- In northern cold climates you will find that most houses have basements. This is because the foundation needs to be below the frost line to prevent upheaval of the foundation when soils freeze.
- Be suspicious of foundation materials that are unusual in your area: if it was such a great idea, why didn’t everyone build a house like that?
- Be suspicious of foundation configurations that are unusual in your area. For example, if all the houses you are looking at have basements and only one has a slab on grade, why did they do it this way? Was it better or just cheaper?
4. Why Do Foundations Settle or Fail?
Foundations fail because they do not adequately transfer the weight of the building to the soils below the house; this leads to settlement in the building which, if left unchecked, can necessitate expensive repairs and even render a house a tear down.
Foundations can fail for two primary reasons:
- The foundation itself was constructed poorly or inadequately
- The soils below the house move and cause foundation failure.
One of the more common reasons the soils below a house do not support the weight of the building is if the soils get repeatedly wet. Remember this: wet soils do not bear weight well. How does the sand support your weight when you are at the beach and a wave rushes up and out around your legs? You sink down in the sand right? The same can be true for houses. Imagine that a house has a roof downspout draining right onto the corner of a building for years. The water will wash away the fines in the soils and the soils will no longer support the weight of the building.
However, in some parts of the country, owners of buildings actually need to water their foundation to prevent the soils from heaving as they dry out. This is because the clay in the soils will expand if it gets too dry; this is a great example of how foundations need to be engineered for regional weather and soil conditions.
Foundations are one of the crucial bones of your house. Foundations are very fixable, but often at great expense. In my experience, foundation repairs can be frustratingly complex: you might find that you have three contractors look at a problem and they propose three different solutions. Structural engineers are a great resource for helping diagnose and repair structure problems, but expenses can mount quickly once you get into engineered structural repairs. There is nothing fun about a foundation, but smart homebuyers will take some time and ask questions and learn about common foundation materials, configurations and problems in an area they are looking for a home. Always hire an experienced home inspector who should be trained in looking for red flags that could indicate a structural problem with a home.