Every house you see has a foundation, but not every house features the same type of foundation because there are a host of house foundation types to choose from. The house foundation type you end up with will depend on your geographical area, the house design, soil, climate, your budget, and the moisture conditions. House foundation types vary, but your home or addition will typically have a crawlspace, daylight or full basement, or a concrete slab-on-grade foundation. These are serviceable, and they can even be flexible in some cases. They work across a huge range of climates and needs, and we’re going to dive into them plus more house foundation types below.
1. Slab House Foundation Types
The slab-style house foundation type is the most budget-friendly, simplest, and most common foundation you can get. At the core, you get a slab of concrete that is between six and eight inches thick that gets poured directly onto a soil surface that your contractor added gravel to in order to help it drain better. You can build a slab foundation in a few different ways, including:
- Frost-Protected (FPSF) – This type of foundation has a rigid foam insulation on it to prevent the ground directly under it from freezing solid. This reduces the risks of cracks to the foundation as the temperatures drop. You only use this house foundation type in buildings that get heated throughout the winter months.
- Slab-on-Grade – In order to create this foundation type, the contractor will pour concrete onto already prepared soil. They’ll pour it thicker along the edges to create footing. They’ll then add rebar to make it stronger, and they can add wire mesh to reduce the risk of it cracking with age or ground movement.
- T-Shaped – This concrete slab foundation uses concrete footings that fall below the frost line, and it has walls that go on top of the footings that reach the soil’s surface. They’ll pour your concrete slab on top of this supportive structure and allow it to harden.
Once the concrete has time to cure, they’ll build the addition or house directly onto it. This removes the need to have a flooring support system in place, and this speeds up the entire construction process to reduce your overall costs.
Benefits of Slab House Foundations
There is no open space under the house, and this reduces your chances of having mice, termite, or pest infestations. Since this house foundation type doesn’t need to rely on beams for additional support, they’re extremely sturdy. They’re also great for heavy or rocky soils since they only need minimal digging, and it’s a solid choice if a basement or crawl space is impractical.
Drawbacks of Slab House Foundations
Natural gas, water, and drainage pipes usually get embedded right inside the concrete, and they’ll eventually leak and wear out. When this happens, you’ll have to open the foundation to repair these areas. Also, this style of foundation is vulnerable to pressure caused by thawing and freezing ground, so they’re better for warmer climates where the ground rarely, if ever, freezes. They also can’t protect your home from flooding the way a basement or crawl space can, so they’re not a good choice for any areas that are prone to flooding.
2. Basement Foundation Types
A basement house foundation type is the deepest option out of the three main styles. A full basement will match almost all or all of the floor space of the house level above it, and the basement is usually a minimum of seven-feet high. Newer homes usually come with taller basements to allow you to convert it into a living space later on if you desire, like a kid’s room, entertainment center, bar, or man cave.
The biggest benefit of having a basement is that it gives you a decent amount of additional space for living or storage. In some instances, finishing your basement area is a great way to almost double your living space. You can also condition or heat and cool your basement like the rest of your home or leave it unconditioned. Generally speaking, there are two main house foundation types that feature a basement.
A full basement is one that is just as large as the floor above it. So, if you have 900 square feet on your ground floor, your basement will equal right around 900 square feet to make it a true full basement. This type of basement has structural foundation walls that feature the foundation footings. These footings go along the basement’s perimeter, and the footings usually drop below the frost line. The frost line is the depth the ground freezes at during the colder winter months.
If you have a basement that has a ceiling height of seven feet or more, you have a very valuable asset. You can easily convert it into a living space, or it can be a kid’s play area, home gym, home theater, or purely for storage.
A variation of the full basement that is very popular is a daylight basement. This is also called a partial basement. You build it against a slope, and this basement style has one or more sides totally embedded into the ground from floor to ceiling. However, as the slope starts to go down, it exposes one or more sides of the foundation. You can add large doors or windows to allow daylight to stream in.
This type of basement is usually more practical if you want to convert it into a living space over a full basement. They give you the opportunity to add another entrance, and this is necessary if you want to rent it out. Daylight basements also avoid a lot of the common issues with basement living because they offer more air and natural light. Mildew and mold are much easier to manage in this type of basement over a full one.
Benefits of Basement Foundation Types
The basement is an excellent place to house any appliances related to your home’s utilities, like your water heater or furnace. This house foundation type gives you easy access to them, but it also increases your access to the ducts and pipes to make it easier to repair or maintain them. The basement also gives you a nice place to hook up your washer and dryer to free up floor space in the main living area.
If you’re a creative person, you can easily turn this space into a workshop for your hobbies, a home bar or pool room, or a home theater. As another benefit, the air space you get by having a basement under your main house allows you to keep things cooler during the summer months.
Drawbacks of Basement Foundation Types
Once you build a basement, you’ll have to insulate and air seal it to prevent unwanted heat gain or loss. If you live in a flood-prone area, you’ll have to take steps to install a sump pump to get rid of any water that seeps into the basement. Ensuring that your basement is properly dry, air sealed, and clean will also prevent issues with mold and pest infestations.
If your house is on limestone or bedrock that is very close to the surface, digging a basement could be impractical at best and impossible at worst. Water-logged or heavy soils, like wetland or clay soils, are also impractical or difficult locations to install a basement. In these areas, if you want to have your house foundation type off the ground, you should consider a crawl space-type area.
3. Crawl Space Foundation Types
If you have a house foundation type that is a crawl space-style, you’ll get very short foundation walls that stand on footings. Since the walls are so short, they create a space that you will literally have to crawl through, hence the name. They can also be four feet tall, and this will give you enough room to store things or for a furnace or other equipment.
Generally speaking, this is an unheated space that you can ventilate by installing small vents that penetrate your foundation walls to provide a small amount of airflow through the space. This house foundation type is less expensive than trying to install a full basement because you don’t have to excavate as much, and you won’t have to pay as much to build the walls or for materials. Just like full basement foundations, you’ll typically use poured concrete walls or mortared concrete blocks. The contractor will use one of two methods to build this house foundation type, including:
- Pier-and-Beam – Concrete footings in the ground will provide support to wood piers and concrete beams that stretch between these piers.
- Stem Wall – This is a continuous masonry wall
Benefits of Crawl Space Foundation Types
This type of foundation is a good pick if you live in an area that has a higher water table or is prone to flooding. It protects your home by preventing it from shifting soil when it rains heavily, and you can also use it to reduce the risk of flood waters getting into the house by adding flood vents. It gives your home air circulation under the house, and this can help keep the rooms above it cooler in the summer. Contractors will usually put utility lines and pipes here, and this allows you to reach them if they need repairs or routine maintenance. Finally, it doubles as a small storage space.
Drawbacks of Crawl Space Foundation Types
You have to insulate your crawl space correctly and maintain it to prevent pest, cold drafts, moisture, or mold problems. Depending on the design of your home and the climate, this could mean that you have to add a vapor barrier with rigid foam insulation along with vents. Another option is to completely encapsulate the space by sealing off the vents and installing a dehumidifier and a sump pump.
Construction Methods for House Foundation Types
It’s possible to build your house foundation types in a few different ways, but there are a few standard construction methods to consider. We’re going to outline them below to give you a good understanding.
Footing and Stem Wall
A footing and stem wall-style foundation is very common in areas that get low or moderate frost because they’re extremely stable. The construction process has several steps, including pouring the footer before laying blocks to establish the wall to your chosen slab height. This house foundation type will take a while to finish, but you get an extremely solid foundation that is resistant to ground movement or water.
Pier and Beam
You’ll find this foundation style in industrial or commercial applications. However, they’re also popular in bigger residential homes because many contractors will utilize drilled shaft concrete piers and beams. This type of foundation is ideal when you have clay soil with a higher plasticity. However, you’ll need a structural engineer to monitor this building project since the soil analysis and design are vital factors to help ensure you get a robust and safe build.
Pier and Beam for Manufactured Homes
If you have a manufactured home installation, you’ll need a different pier and beam foundation type. It’s usually more affordable. To start, your contractors will put anchors into the ground to hold it secure against bad weather and strong winds. Next, they attach straps to the home to anchor it in place. They then use outriggers and cross-members to add more weather resistance. You can have a steel base, but it’s also possible to put ABS plastic pads or concrete underneath it. The installation process can go much quicker with this house foundation type, but it only works with mobile or manufactured home styles.
A pre-poured slab is a precast foundation panel that contractors use heavy equipment, like a crane, to slide into place. This can make your whole installation process go much faster from start to finish, but it’s also much more expensive than simply using a poured concrete slab.
Slab-on-Grade (Monolithic Slab)
When your contractor pours a slab-on-grade or a monolithic slab, they do the pouring process in one go. The stem wall, footing, and concrete subfloor all go down on the ground at the same time. You’ll get a slab that is a few inches thick. Instead of having traditional footers, you’ll get thicker slabs where the load-bearing walls go. Slabs will have either cables or rebar for strength, and they can handle garages, homes, sheds, or other buildings.
Site Considerations for House Foundation Types
Depending on your layout and the building site you pick out, certain types of foundation may work much better than another. A few factors that will directly impact your final choice include but are not limited to:
The local climate will influence which house foundation type you pick out. Frost is a huge factor. If you live in a climate that sees routine freezing and melting once a year, you could easily end up with cracks in a slab-on-grade foundation. This is where a post and pier foundation would be a much better choice.
If you live in an area that is at a higher risk for having tropical storms, you want a foundation type that can withstand flood waters. So, again, having a post and pier foundation style is a better choice than a slab or a full basement in this instance. If you live in a more moderate climate, a monolithic slab style is a budget friendly and sufficient choice.
The soil conditions, including the hardness, different layers, and the type of soil will influence which house foundation type is best for your home. If you have stable ground, you won’t need as robust of a foundation as you would necessarily need on soft soil. In this case, a drilled pier foundation is a great choice to ensure that your home is on hard rock instead of soft surface soil.
The backfill type you need will also influence your foundation’s stability. Most people pick out a store-bought filler material like aggregate or limestone to backfill in the foundation, just like you would for a concrete or gravel driveway.
The water table is the boundary between saturated and unsaturated soil. As the seasons change, the water table level will rise and fall. Depending on your lot, this could impact how well it drains at the building site. Water can easily seep out of the ground and negatively impact your foundation.
Cost and Pricing for Foundations
The cost for your house foundation type will depend on several different factors, including your average labor costs for your location. The biggest deciding factors for this final price are below.
Generally speaking, the foundation cost will range anywhere from $4,000 to $175,000. The time required to finish the foundation, materials, and the house foundation type you pick out will all factor in. If you have a slab basement foundation, you’ll typically pay below $21,000. A basement foundation can easily go up to $175,000. Based on the house foundation type, you can expect to pay around:
- Basement Foundation – $10,000 to $175,000
- Crawl Space Foundation – $8,000 to $21,000
- Slab Foundation – $4,500 to $21,000
You’ll also need permits before you start building your foundation, so make sure that your contractor will handle them. If they don’t, you’ll have to secure them before construction begins.
The house foundation type you pick out is the single biggest cost factor to consider over everything else. As we showed you, the most expensive foundations are basements, and this is especially true if you want a finished one. The concrete slab is the least expensive option. A crawl space-style foundation falls right in the middle, and many pre-made concrete foundations are right around the same price point.
The deeper the foundation is, the more expensive your entire project will be. However, many climates dictate that you need a very deep foundation that sinks below your area’s frost line. This is necessary to help protect the home and the structural integrity of the whole thing.
Other Pricing Considerations
Any extra features, material pricing, and transportation costs will also factor into your final price. For example, if you want to have heating under the floor, this can help you save on burst pipe costs and overall heating bills. However, this adds a decent amount to the final price. If you need more sealant or waterproofing due to site drainage issues and the climate, those all start to add up quickly.
The lower your home’s square footage is, the cheaper the foundation can be. You’ll spend between $4.00 and $7.00 per square foot for concrete-style foundations. A single-story foundation is usually more expensive than a multiple-story one. This may seem backwards, but the upper floors don’t require additional concrete, and this lowers your costs.
Final House Foundation Type Considerations
If you’re still not 100% sure which house foundation type is best for your area, you can use the following criteria to help narrow down your options to the best choice. Also, always consult a professional contractor to get an idea on what they recommend.
Home Design and Style
The overall design of your home could be the deciding factor on the foundation you’ll put in. Another option is to install a mobile home over whichever foundation you pick out. You can put a manufactured home on virtually any type of foundation, but many people choose to go with the pier and beam foundations that are unique to this house style. It is possible to pick any foundation you want, but engineering issues and costs can start to creep up throughout the project.
Lot Grade and Soil Type
If you live in an area that has a mild climate, you may mistakenly think that you can pick out any foundation you want. However, your lot’s grade and where you decide your home is going to go will affect how compatible certain foundation types are. The soil will also factor into your foundation’s construction. If you have rock below the site, you might need to bring in a structural engineer to look at the lot and come up with a viable building plan. In other instances, having unstable soil could mean that you have to move your proposed build site to make it safer.
The lot grading can also play in to having a certain type of foundation. You may decide that you want a daylight basement, but if you don’t have the budget for the necessary modifications or the lot isn’t graded just right, you may be forced to change your plan to a traditional basement.
Some foundations don’t work with specific climates. For example, if you want a slab foundation, you can’t live in an area where extreme temperature swings happen. As the water in the ground thaws and freezes with the season changes, the concrete can crack due to pressure buildup. On the other end of the spectrum, wooden foundations won’t do well in warmer climates due to pest issues like termites. The climate plays a huge role in your house foundation type, so you shouldn’t pick out one until you understand which ones work best for your climate zone.
Utilities and Accessibility
Some foundation types make it very easy to get in and fix things or maintain them to prevent bigger problems. For example, you may need to access the plumbing through a crawl space. However, if you have a poured concrete foundation, the pipes can get encased in a few inches of concrete. How accessible your utility lines are will depend on the house foundation type you pick out and the features inside or underneath it.
Common Foundation Problems
There are two main foundation problems you want to worry about and avoid if possible because they can lead to huge issues down the road with very expensive repair bills. They include:
A hairline crack in a concrete wall or slab usually isn’t a big deal or needs repairs. However, more severe cracks can indicate that you have a bigger problem that needs immediate attention. Ideally, you’ll get a contractor out who specializes in masonry work or foundations to look at it as soon as possible. You should call in a professional when the crack is non-uniform or:
- There is water coming from the crack
- The crack is more than ¼-inch wide
- The crack runs through a concrete brick or block as opposed to running through the mortar between these things
- The crack presents a displacement where one part of the crack sticks out further than the adjacent part
Water is the cause or more damage to foundations on houses than any other single source. Keeping water out of the house is the best thing that you can do if you want to avoid problems in the foundation itself or somewhere in the house. To pull water out of the air, you can use a dehumidifier.
Making an effort to keep the water out will take care of almost all of your foundation water damage problems. Generally speaking, the soil should slope away from your home’s foundation at a six-inch vertical slope, and this should be within the first 10-feet horizontally. Any hard surface by the house like a driveway should slope away from your home’s foundation at a rate of ¼-inch per foot. Any roof runoff should use gutters to channel it away from the foundation. Your downspout should discharge a minimum of five-feet from your home’s foundation.
These three house foundation types and the various components that go into helping you make the final decision. If you get it right, you’ll get a virtually maintenance-free option that won’t give you any issues for years after the initial installation process.