Strong Like Bull: What's the Strongest Foundation for a House?

April 29, 2021

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If you’re having a new house built or need your home’s current foundation reworked, you might ask, what is the strongest foundation for a house? This is vital to know, as foundation repairs and full-scale renovation are expensive projects, so a homeowner will want to choose a foundation that lasts as long as possible before it needs repairs or replacing.

Full basements are the strongest foundation for a house, and basements also provide added living or storage space. Crawlspaces, slab foundations, and pier and beam foundations are also strong and durable but don’t offer the same support as basements.

Knowing the vital differences between the four main foundation types can help you decide the best choice for your new construction or home renovation. You can then discuss your options with a foundation installation contractor near you and ensure you make the best decision when it comes to a new foundation for your property.

What Type of Foundation is Best for a House?

In addition to strength, it’s vital that a property owner consider a foundation’s expected maintenance costs and other added pros and cons of various options. Note what makes the four most popular foundation choices best and then you can discuss each one with your contractor as needed.

Basement pros and cons

Basements provide excellent support for a home and add a layer of protection against the elements. A basement also provides added living or storage space; even if you don’t finish the basement space, simple waterproofing can mean a clean, dry space perfect for keeping the home’s furnace, water heater, washer and dryer, and other such items.

Because basements provide added space and foundation strength, they can also increase property values, more so than other foundation options. However, the downside of basements is that they are the most expensive foundation option, often costing anywhere from $18,000 to $30,000. Basements are also not always an ideal choice in areas with overly moist soil.

Crawlspace pros and cons

A crawlspace requires limited excavation, making it a faster and more affordable option than basements. With high-quality encapsulation, a crawlspace can also provide some storage under the home while allowing access to plumbing pipes, wiring, and other such fixtures and features.

Crawlspace installation typically averages around $7 per square foot, or between $8000 and $20,000 on average. In very humid environments, a dehumidifier might be recommended, to avoid wood rot and mold; these might cost an added $70 to $1000. While crawlspaces are easier to install than basements, they don’t offer added living space so they don’t tend to add value to a home.

Concrete slab pros and cons

Slab foundations are an excellent choice where soil conditions don’t support a basement or crawlspace. Slabs also offer fast and affordable installations, usually ranging from around $7000 to $20,000. Their easy, affordable installation is often why slab foundations are often used in developments where identical or similar homes are constructed quickly.

Slab foundations are not good for colder climates, as ground freezing and thawing can cause soil to expand and shrink excessively. This freeze-thaw cycle puts pressure on that concrete, risking cracks and other damage.

Pier and beam foundation pros and cons

Concrete technologies improved significantly during the 1960s; before this time, pier and beam foundations were the most popular for residential homes. Pier and beam foundations consist of blocks or piers inserted into the ground and which provide support for a structure. This elevation keeps homes away from the soil, which is an advantage in tropical areas or those prone to flooding.

Pier and beam foundations are reasonably priced, usually averaging between $8000 and $15,000, but they do need some type of fencing or another cosmetic cover. They also add no value to a home, except for beachfront properties that might need added elevation to protect against floods or rising sea levels.

Basements Crawlspaces Slabs Pier and Beam
Pros Typically considered the strongest foundation
Adds storage and living space
Improves property values
Requires less excavation than basements
May offer some storage space
Economical and quick to build
Requires less excavation than basements and crawlspaces
Can prevent insect infestation
Reasonable price
Protects home in case of floods or rising sea levels
Cons Most expensive option Encapsulation or dehumidifiers are recommended, to prevent rot and mold Not suitable for colder climates
Accessing plumbing pipes run through slab foundations might require added excavation
Zoning laws often restrict pier and beam foundations to beachfront properties
Average Cost $18,000 to $30,000 $8000 to $20,000 $4500 to $21,000 $8000 to $15,000
Maintenance Waterproofing or seal coating, crack filling Encapsulation and dehumidifiers Crack filling Waterproofing, maintaining cosmetic covering
Longevity 100 years or longer 100 years or longer 50 to 100 years 50 to 100 years

What Type of Foundation is Best for a House?

white basement

A homeowner would do well to consider more than just pricing when deciding on a foundation type. Note a few added considerations that will help you decide the best foundation type for your new home construction or foundation renovation:

  • If you’re concerned about resale values, consider how a basement might improve property values and make your home easier to sell in the future.
  • Basements are an excellent option for storing appliances as well as personal items; this can be especially vital for larger families or anyone with lots of sporting goods, craft supplies, or other items that would otherwise be underfoot in your living space.
  • A finished basement not only provides added living space for your family but, where zoning laws allow, can also be converted into a full apartment, such as for a family member or to use as income property.
  • High humidity and moisture levels affect basements and crawlspaces more than slab foundations. If you decide on a basement or crawlspace in a humid area, ensure you’re ready for consistent waterproofing, encapsulation, and other maintenance tasks.

The Components of a Strong House Foundation

shovel digging into the soil

A foundation’s strength is measured by more than just the amount of weight the material can hold! A foundation needs to withstand moisture and soil pressure as well as temperature changes. As an example, a slab foundation eliminates the space under the home that traps humidity; without proper waterproofing and encapsulation, a basement or crawlspace foundation might eventually suffer cracking, wood rot, and other serious damage in a humid environment.

Also, consider your home’s overall size and if you might add to its space over the years. Basements help distribute a home’s weight across its outer span, offering added strength. Concrete slabs are better for smaller, lighter homes, as its weight is concentrated on the center of that slab. If you think you might add another story to the home or an attached sunroom, ensure you choose a strong foundation able to handle that added weight.

If you need to choose a foundation for new construction, talk to your builder or a structural engineer about your options and plans for your home. He or she can offer suggestions for the best option, both for immediate needs and your long-term homeownership goals.

Depth Requirements for House Foundations

concrete poured onto foundation for repair

A strong foundation is vital for any home, perhaps more so than any other material or surface used to construct a house. A poorly installed roof, for example, will lead to water damage and mold and might even eventually collapse, but even the poorest-quality roof won’t cause an entire home to sink and crumble!

Zoning laws dictate a foundation’s needed depth and other construction details but note that those building codes should be considered the minimum requirements for a strong, stable foundation. Depth is also just one factor to consider when pouring a new foundation; note a few other factors here so you can determine how deep a foundation should be for a house.

Grading

Properties must be graded or sloped slightly towards a street or drain, to allow for moisture runoff. Without proper grading, moisture will collect around the foundation and risk softening, cracks, wood rot, and other damage. The foundation footings exterior should slope at a 5% minimum and continue at this grade for at least 10 feet.

Load-bearing value of soil

The load-bearing value or LBV of soil refers to how much weight it can hold. Undisturbed soil is typically stronger than soil that has been turned or excavated, while certain soil compositions are also stronger than others. Bedrock, for example, has a 12,000 LBV, while gravel offers only a 3000 LBV. Clay and sandy soil offer the least LBV, at about 1500.

Before foundation installation, it’s helpful to have a landscaping engineer test the soil and note its overall composition. He or she can also tell you its LBV, so you know if it’s strong enough to support your chosen foundation or if the soil needs added treatment to make it stronger overall.

Footing depth

Foundation footings should extend at least 12 inches below undisturbed soil and 12 inches below what is called the frost line, or the depth to which the ground freezes in winter in that area. Note that decks and other smaller outbuildings and structures might have different requirements, as they won’t be supporting as much weight as an entire home.

Footing width

Generally speaking, one-story buildings should have a footing width of at least 12 inches for soil with the lowest LBV, while two-story buildings require a footing width of 15 inches or more. For soil with LBV of 2000 or greater, some areas lower this requirement to 12-inch width.

Concrete strength

Most areas require concrete strength of 2500 PSI or greater for residential homes. A lower PSI might be allowed for garages and other smaller structures. In areas with severe weather conditions, zoning laws might require 3000 PSI or greater.

How Long Does a House Foundation Last?

big tree roots lead to foundation repair

While every foundation type has its own expected lifespan, note that how well you maintain that foundation over the years affects that lifespan, perhaps more so than its materials and installation! To ensure your home’s foundation lasts as long as possible, note some tips for avoiding otherwise unnecessary foundation damage:

  • Invest in waterproofing services frequently. Moisture inside or outside the home seeps into foundation concrete pits and pores, softening the material and leading to cracks, chips, and spalling. Professional waterproofing, reapplied as often as recommended, will help repel that moisture and keep the home’s foundation strong.
  • An outside dehumidifier is often needed for crawlspaces, while an inside dehumidifier is an excellent choice for keeping basement walls and flooring dry and secure! If your home’s basement is consistently damp, a sump pump can be a better choice for protecting that foundation.
  • Ensure your property stays graded properly over the years. Erosion, trapped moisture, construction projects, and other factors can affect a property’s grade or slope so that the soil might expand against a home’s foundation or hold moisture near the concrete, leading to damage.
  • Keep underground sprinkler systems in good repair so they don’t leak moisture into the ground.
  • Tree roots can wrap around a home’s foundation and, as they continue to grow, put pressure on the concrete, risking chips and other damage. Have an arborist or landscaping engineer check the roots of any mature trees on your property every few years and have those roots trimmed or redirected as needed, to protect the foundation from damage.
  • Never add significant weight to a home without checking if the foundation needs added bracing. This weight can come from options such as stone floors or countertops, a slate roof, or an attached sunroom or deck.

Regular foundation inspections also spot damage as soon as it starts developing, so you can patch cracks and spalling quickly before they get more extensive. These inspections ensure your foundation stays in good condition for as long as possible.

The pros here at Kansas City Foundation Repair Specialists hope that this information answers the question, what is the strongest foundation for a house. If you need foundation installation or quality foundation repairs in Kansas City, give us a call. We offer FREE quotes and start every project with a full inspection, ensuring quality fixes that last. To find out more, call us here at Kansas City Foundation Repair Specialists today.

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