Quicklist: Types of House Foundations
- Full Basement
- Daylight Basement
- Crawlspace
- Concrete Slab
- Wood Foundation
- Poured Concrete
- Precast Concrete Panel
- Concrete Masonry Units
- Stone
- Wood
- Footing and Stem Wall
- Pier and Beam
- Pier and Beam for Manufactured Homes
- Slab on Grade/Monolithic Slab
- Pre-Poured Slab
Related: Types of Decorative Concrete | Types of Concrete Cleaners | Types of Concrete Saws | Concrete Alternatives | Cinder Block Dimensions | Use Faced or Unfaced Insulation in a Crawl Space?
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House Foundation Components
House Foundation Guide
You have many decisions to make before construction begins on your new home. Deciding on the type of foundation may be the most important — so knowing what options and materials are available is essential.
The average weight of a house is over 200 tons — including your belongings — so a strong foundation is crucial if you want a home that will last.
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A. House Foundation Types
There are three main foundation types; basement, crawlspace and concrete slab. A fourth, but a less common option, is a wood foundation.
1. Basement Foundation (Two Types)
Full Basement
Basement foundations have structural walls extending underground. Two types are common: full and daylight. A full basement is entirely underground, either with no windows or small ones at ground level.
Basement foundations can be finished (see finished basement ideas here and see the different types of finished basements here) or unfinished. Unfinished basements often serve as storage areas or contain water heaters, furnaces, and other household equipment.
Daylight Basement
A daylight basement is on a slope. Some walls are below ground, blocking daylight, and others are partly or entirely above-ground.
Achieving a daylight or walkout basement requires the right slope on your lot. But if you don’t mind spending a lot of money on prepping your home-build site, it is possible to grade the lot to accommodate a daylight basement.
Basement foundations require either concrete masonry units (CMUs) or concrete walls (poured concrete). Basement foundations are the most expensive option, but they also let you extend your living space if you decide on a finished basement.
2. Crawlspace Foundation
A crawlspace foundation involves short foundation walls on footings. These types of structures are usually unheated but have ventilation to avoid moisture buildup. They use poured concrete or mortared concrete blocks, and they’re less expensive than a full basement.
Many people consider a partial basement to be a crawl space since you can store some items there but can’t convert it into a living space.
3. Concrete Slab Foundation
Concrete slab foundations, or slab-on-grade foundations, are a common option in many areas. They’re best for climates where the ground doesn’t freeze and thaw throughout the winter. These types of house foundations help protect against termites.
Accessing water and drainage pipes can be complicated, however, because those features typically lie underneath a few inches of concrete. Slab-on-grade foundations are one of the least expensive foundation options.
4. Wood Foundation
Wood foundations are often standard in northern areas. They can have a crawl space underneath, too. It’s also common to find basements that layer pressure-treated wood on top of concrete floors—but technically, such a combination would count as a concrete foundation.
B. Types of Home Foundation Materials and Methods
Though foundations are often cement or wood, there are variations. Here are common materials you can find for foundations.
1. Poured Concrete
Poured concrete walls are dense, resisting breakage and cracking. Many builders prefer them over concrete blocks because they don’t allow water or earth in since they’re a solid piece.
2. Precast Concrete Panel
3. Concrete Masonry Units
4. Stone
Stone basements are no longer common, but you might find them in older houses. These types of house foundations use a mixture of stones and a mixture of cement to form a solid barrier. They can crack and chip, so most builders shy away from such materials in modern homes.
Of course, nothing is stopping you from adding a stone façade to your basement or foundation.
5. Wood
Since about 1960, pressure-treated lumber has been a common foundation material. Wood foundations are cheap, easy to assemble, and can resist moisture and insects. However, wood doesn’t last forever, so it’s gradually become less popular as a foundation-building material.
C. Types of House Foundation Construction Methods
You can build a foundation in a few different ways. Here are some other standard construction methods.
1. Footing and Stem Wall
A stem wall foundation is common in areas with low to moderate frost because they are very stable. The multi-step process involves pouring a footer, then laying blocks to form a wall to the finished slab height.
Footing and stem walls take a while to complete, but the result is a solid foundation that is resistant to issues like water and ground movement.
2. Pier and Beam
Pier and beam foundations are more common in commercial and industrial applications. However, for larger residential homes, many builders will use drilled shaft concrete piers and beams.
A pier and beam foundation is ideal where the soil is clay and has high plasticity. But you’ll also need a structural engineer to oversee the project since the design and soil analysis are vital factors for a safe and robust build.
3. Pier and Beam for Manufactured Homes
For manufactured home installations, a different type of pier and beam foundation is useful (and often affordable). First, anchors go into the ground to hold against wind and other weather. Straps attach to your home’s steel frame to hold it in place. Then, outriggers and cross-members go on to add extra weather resistance.
The base can be steel, but you can also opt for concrete or ABS plastic pads underneath. Installation can be quicker with this foundation, but it’s only applicable to manufactured or mobile homes.
4. Slab on Grade/Monolithic Slab
When construction workers pour a slab on grade — aka, a monolithic slab — they complete the pour in one go. The footing, stem wall, and concrete subfloor all go down at the same time, and the slab is a few inches thick. Instead of footers, there are thicker areas of concrete where load-bearing walls go.
Slabs contain either rebar or cables for strength, and they can handle homes, garages, sheds and more.
5. Pre-Poured Slab
D. More Details on Foundation Types
Here are the factors that affect foundations, plus pricing and build considerations.
A. Climate Required
Some house foundation types aren’t suitable for specific climates. For example, environments that experience extreme temperatures aren’t ideal for slab foundations. As the water freezes and thaws, the concrete can crack from the pressure. In contrast, warmer climates may not benefit from wood foundations since termites can pose a threat.
Climate is a crucial influence over your build plans, so don’t get too attached to a particular foundation type until you see what will work where you live.
B. Lot Grade and Soil Type
You might be fortunate enough to live in an area with a mild climate, but that doesn’t mean you can choose any foundation. The grade of your lot and where you decide to put your home can affect the compatibility of certain house foundation types.
The soil can also affect the foundation construction. If there is rock below your build site, for example, you might need a structural engineer to examine the lot and figure out a plan for building over it. In other cases, unstable soil could mean you need to select a different build site.
Lot grading can also impact your ability to have a specific foundation build. You might want a daylight basement, but if the lot isn’t graded just so — or if you don’t have modifications in your budget — you might only be able to choose a traditional basement.
C. Utilities and Accessibility
With some types of house foundations, it’s easy to get in and fix things when they break. For example, you might need to enter a crawlspace to service your home’s plumbing. But in a poured concrete foundation, for example, the pipes might lie under inches of concrete.
How accessible your home’s internal structures depend on the type of foundation and the layout of the features underneath or inside it.
D. Home Style and Design
The architecture or overall design of your home may dictate the type of foundation you need. Or, you might be installing a mobile home over the foundation you choose. While you can place a manufactured home on almost any foundation, many homeowners opt for pier and beam foundations unique to manufactured homes.
Of course, you can choose whatever foundation you prefer, but costs—and engineering issues—can creep up, too.
E. Cost and Pricing
The cost of your foundation depends on many factors, including the average cost of labor in your area. Here are the deciding factors when it comes to foundation pricing.
1. Square Footage
The lower the square footage of your home, the cheaper your foundation may be. You can expect to spend anywhere from $4 to $7 per square foot on a concrete foundation.
At the same time, a single-story home foundation is often more expensive than a multi-story one. It might seem counterintuitive, but the upper floors don’t need additional concrete foundations, so going vertical might save you money overall.
Plus, per square foot, it’s cheaper to build a two-story house anyway.
2. Construction Type
Of course, the type of foundation you ultimately choose will influence the price more than any other feature. The most expensive foundations are basement builds — especially if you want a finished basement — while the least costly is a concrete slab.
A crawlspace foundation would be mid-range, though you might find pre-made concrete slab solutions that are around the same cost.
3. Foundation Depth
The deeper your contractor must dig, the more expensive the foundation project will be. But in many climates, you will need to have a deep foundation — below the frost line — to protect your home and its structural integrity.
4. Other Pricing Considerations
A foundation is a foundation, right? Not exactly. Pricing also depends on materials costs, extra features, and transportation costs.
For example, installing radiant heating in the floor, which can save on heating and burst pipe costs, adds a significant bump to the bottom line. If you need additional waterproofing or sealant due to climate or site drainage issues, those can also add up.
5. Average Price of a Home Foundation
A home foundation costs anywhere from $4,000 to $175,000. Pricing varies widely based on the materials, time required, and the foundation type.
For example, a slab basement typically comes in under $21,000, while a basement foundation can cost up to $175,000. Here’s an overview of typical foundation project costs based on foundation type.
- Slab foundation: $4,500-$21,000
- Crawl space foundation: $8,000-$21,000
- Basement foundation: $10,000-$175,000
Keep in mind that foundation projects also require permits, which your builder may or may not handle for you.
E. How to Choose a Foundation Type
If you are building from the ground up, you can choose the right foundation type for your home. Here’s how.
A. Site Considerations
Depending on your home building site and layout, one type of foundation may work better than another. Here are the natural factors that impact your site.
1. Water Tables
A groundwater table is a boundary between unsaturated and saturated soil. Water tables rise and fall with the seasons, and depending on your lot, they may impact drainage at the building site. Water can even seep out of the ground and affect your foundation.
2. Soil Conditions
A drilled pier foundation, for example, is ideal for ensuring your home rests on the hard rock rather than in soft surface dirt. The type of backfill you use also influences the stability of your foundation. Most people choose store-bought filler material such as limestone or aggregate to backfill the foundation.
B. Local Climate
Your local climate can also influence what type of foundation is best. Frost, for example, is a significant factor. If you live in an area where the ground frequently freezes and melts, you could see cracks in your home’s monolith slab foundation. In that case, a post and pier foundation might be a better solution.
Or, if you live somewhere with a high risk of tropical storms, a foundation that can withstand flooding is preferable. Again, a post and pier option may work better than a full basement or slab. Then again, in more moderate climates, a monolith slab is often sufficient and a budget-friendly choice.
C. Foundation Purpose
The purpose of a mono slab is very different than that of a daylight basement. Knowing what purpose you want your foundation to serve is vital since it affects how you’ll use your home.
1. Extra Living Space
If you want to add extra space to your home’s floor plan, choosing a basement foundation might be the right fit. A finished basement adds square footage to your house and can function as an extra bedroom, game room, media room, or guest lodging.
Plus, finished basements enhance your home’s resale value. Only about 30 percent of family homes built after 2013 have full or partial basements. In comparison, 54 percent are on slabs and 15 percent include a crawl space.
2. Outdoor Living
For optimal outdoor living, choosing a walkout (or daylight) basement might be the way to go. You can include windows, stylish doors, and even a patio on your walkout basement. This way, you can enjoy entertaining in your backyard—or even rent out your basement as an apartment unit.
3. Storage
Obviously, a concrete slab or wood foundation doesn’t offer much in the way of storage space. If you want to be able to stow belongings—or appliances like the water heater—below the floor, a foundation with a crawl space is a must.
4. Stability
Most homeowners want stability in their foundations. But for people who live in floodplains, a stable foundation is the top priority when building. Elevated slab foundations are one innovative solution to flood issues.
An elevated slab foundation, like Tella Firma’s, combines a slab foundation with a pier-and-beam system. The elevated foundation takes a little longer to build and is more expensive than standard foundations—but it can save you money if water damage is a concern.
The suspended foundation is ideal for clay soils, which expand and contract throughout the seasons, and wetter conditions.
F. Best Foundation Types for Various Purposes
Best foundation for energy efficiency
If you’re building a passive or energy-efficient house then it’s essential to start with the foundation. The foundation should contribute to keeping the house air-tight, thus natural materials such as rammed earth, recycled steel, and straw bales are the preferred options.
The goal is to use advanced building techniques with eco-friendly principles that provide excellent insulation and heat retention.
Best foundation for cold climates
The most common foundation types for cold climates are the beam foundation and the slab foundation. The difference is that on a beam foundation, the weight of the house is laid on two rebar beams, whereas a slab foundation is based on a whole slab.
A beam foundation is usually much deeper and more reliable but it can absorb water over time. You can choose the depth and the height of the beam foundation but you can’t play around with a slab foundation that much.
Best foundation for hard rock
Digging for a foundation on hard rock is extremely difficult. Instead of doing that, you can use the large boulders of your home’s location as your foundation. Simply drill into the stone and put in your rebar to create a solid and hardy foundation that’ll last for generations.
Best foundation for unstable ground
The best foundation system for unstable ground is piled raft. This would consist of concrete piles with concrete rafts suspended on top.
Make sure to use steel posts and polystyrene to support the steelwork and stop any pressure on the foundation and support it through years of shrinkage and expansion from the ground.
Best foundation for elevation
To create stability for an elevated structure, your foundation needs to be quite a large structure. You want to use a slab with foam insulation below it. This causes the floor platform to be very tight and closed.
If you’re adding an extension on an existing structure; say building a garage; you would do well to build your foundation with fill soil, follow by gravel to divert any water that gets into the retaining wall and drain it through the gravel safely away from the building.
Best foundation for an earthquake zone
Building houses that are resilient in the face of hurricanes, storms, and earthquakes take a lot of thought. The goal is to build a foundation that’ll minimize the damage from a significant quake while protecting your investment.
If the ground is moving abruptly beneath the structure, you need something that can move quickly with it, and the lighter and more rigid the structure, the better.
While all the elements of the house should be very well connected, the foundation shouldn’t be as connected to the ground and the house should be able to move independently of the ground.
A good foundation for an earthquake zone would be one made from metal plates with plastic pushing between them made of high-density polyethylene. Wooden houses also don’t flex much, so long as they have lots of bracing. This makes for a strong and lightweight structure.
Best foundation for difficult terrain
By far the most common type of foundation for difficult terrain is a concrete slab. The first step is to reinforce the soil with a stiff slab and cover this with tough and durable plastic wrap; this layer acts as a vapor barrier for the house.
This is important for keeping moisture coming from the soil off the slab. You’ll want to cut channels into the vapor barrier and fill them with a grid pattern of rebar and concrete to add stiffness to the slab.
Once the rebar has been placed, you can place a fine wire mesh over the grid and lay extra rebar at a 45-degree angle on the corners to prevent cracks from forming over time.
Finish off the project with a concrete pour to get the perfect finish and cover the entire slab with black plastic for five or six days in order to make sure the slab has all the water it needs.
Frequently Asked Questions
What are house foundations made of, and how are house foundations built?
Most house foundations are made of concrete. Other materials, such as brick, stone, or treated lumber, can be used as well.
When building a concrete foundation, builders begin by clearing the ground and leveling the soil. Wood is used to build a foundation frame, with rails used for reinforcement. From there, the concrete is mixed and poured into the foundation frame.
Can tree roots damage house foundations?
Tree roots can cause structural damage to a home’s foundation. If a tree needs water, it may drain the moisture from the soil around the foundation, causing the soil around the foundation to shift.
This can leave the foundation without support, leading to issues like cracks or buckling concrete.
Can ants damage house foundations?
Some types of ants, like carpenter ants, are known to burrow into wood. When they infest house foundations, they can damage wood supports.
Pavement ants may also nest in foundations, but they’re unlikely to cause any structural damage.
Can ivy roots damage house foundations?
Ivy plants have strong roots and can damage brick, concrete, and wood foundations.
If ivy is growing out of foundation cracks or creating new cracks, it should be removed. When getting rid of ivy, it’s best to use a pesticide or manually remove the plant’s roots.
Can bamboo damage house foundations?
Since bamboo is fast-growing and invasive, it poses a bigger threat to house foundations than tree roots. Wood, asphalt, and brick can all be damaged by bamboo roots.
While bamboo won’t create new cracks in a concrete foundation, it can make existing cracks worse.
Can tree roots affect house foundations?
Tree roots can drain water from the soil around a house, leading to soil shifts.
When soil shifts, the foundation can shift as well, leading to damage. A tree’s roots may also enter existing cracks in the foundation, causing those cracks to expand.
What happens if a house foundation is cracked?
Foundations provide a home with support and keep it from sinking into the soil below.
Structural cracks can cause the foundation to move, compromising the stability of the building. Smaller hairline cracks won’t cause structural issues, but they can be a source of leaks.
How long can a house foundation last?
Concrete, brick, and stone foundations can last for more than 100 years if the foundation is properly constructed.
However, the waterproof coatings used to protect foundations should be reapplied every 10 years. Regular maintenance, such as inspections, leak repairs, and slope damage, can extend a foundation’s lifespan.
Can you raise a house foundation?
A house can be raised up to 12 feet above its foundation. This is typically done when a foundation is severely damaged and needs to be replaced. On average, it costs between $20,000 and $100,000 to lift a house and replace a damaged foundation.
If a foundation is no longer level, it’s also possible to lift part of the foundation using a method called slab jacking.
This process involves drilling holes in the foundation and pumping it with grout or polyurethane foam. This can raise the sunken portion of the foundation, making a house level again.
Can you paint the house foundation?
Foundations typically have some sort of protective coating, but it’s possible to paint over many types of coatings.
However, there are certain coatings, such as tar coatings, that will have to be removed before the foundation can be painted.
Waterproof paint can potentially protect a foundation from both water and UV damage.
Can you fix a house foundation?
Although replacement is sometimes necessary, it’s possible to repair most types of foundation damage.
Masonry patches and sealants can be used to patch cracks in the foundation, which can keep them from expanding.
Methods like slab jacking and foundation push piers can be used to raise a foundation that’s started to sink.
Can a house foundation be poured in the winter?
It’s possible to pour a concrete foundation in the winter as long as temperatures are above freezing and the soil is frost-free.
Concrete is sensitive to cold temperatures, so it must be protected as it sets. Some concrete mixes contain additional cement and are specifically designed for colder temperatures.
