Raised vs. Slab-On-Grade Foundations (What’s the Difference?)

Are you considering remodeling your home? Are you figuring out the best foundation for your home? Are you curious to know what kind of foundation your home has?

Welcome to the battle of many centuries. You’ll be seeing these types of foundations for years to come. Raised and slab-on-grade won’t be going away anytime soon. Learn more about these contestants as we lay out how these opponents match in a 1v1. 

Dalinghaus Construction, a judge in foundations since 2015, has inspected over ten-thousand homes in Southern California and Arizona. We’ve crawled the spaces in the raised foundations when no one else wanted to look. We’ve lifted slab-on-grade when it was feeling more slab-off. We’ve accepted both for their benefits and their flaws. It’s time to compare so you can place your bets.

What is a Raised Foundation? 

It’s a foundation that allows the framing of the house to be above the soil. They oftentimes have accessible crawlspaces. It has a concrete footing that has part of it 12-18 inches below the soil and can go above at many variations of inches or feet. On average, we see the footing go 18 inches above the ground, sometimes three to four feet, but can go higher.

The sill plate is attached and bolted to the concrete footing, making sure the house doesn’t become a slip-n-slide.

They’re built as high as they need to go due to the materials needed. Anyone is welcome to have a raised-so-much-higher foundation (made up term), but it does cost extra money

Raised Foundation Pros:

  • If there is a plumbing or electrical issue, you can crawl under and fix it. Hopefully, both won’t happen since we don’t want you to look like any Looney Tunes character when they experience electricity firsthand.

  • Better with cold temperatures and handles frost layers better.

    • Frost Layer – the most common depth in which the groundwater in the soil can expect to freeze.

  • Less expensive on sloping areas such as mountains or hills. 

  • To install a slab-on-grade foundation on a mountainside, which can happen, would be expensive due to having to excavate. Building a raised foundation can be done along a hillside. 

  • Is able to handle flooding better.

    • Your house generally won’t be in a flood-prone area. That said, if you experience six inches of rain, the six inches will hit the footing before it hits the house framing. 
  • Faster to build.

    • Less concrete for a raised foundation. Concrete takes longer to cure. 
  • If the raised foundation is with a crawlspace, it offers room for storage. 

  • More Remodeling Options.

    • Piping and electricity are fixed into a slab-on-grade foundation. Piping would require removing the concrete and repouring later.
  • Raised foundations provide easier access to all your pipes. 

Raised Foundation Cons:  

  • Moisture issues.

    • The crawlspace needs moisture mitigation and control with proper venting to prevent moisture build-up, mold, and wood deterioration.
  • More expensive.

    • Concrete used to be more expensive back in the day. Nowadays, concrete is as cheap as dirt. We’re not even kidding. You can buy a bag of soil and a bag of concrete for around the same price at Home Depot.
    • Wood is an extra factor, which has recently been more expensive. 
  • Termites and other insects can be a problem. 

  • Higher Maintenance.

  • Inspections should happen once every one to two years.

    • Note: It’s not required. It’s recommended since Raised foundations have wood as an additional material compared to slabs. 

What is a Slab -on-grade Foundation?

This type of foundation consists of two parts:

  1. A Concrete Slab – This is what your home sits on top of at the surface of the “active zone,” or the area the soil is most susceptible to the elements. This slab can be four to six inches thick.
  2. A Footing – this goes around the perimeter of the slab, as well as areas where there may be load-bearing walls (walls that carry a significant amount of weight, usually a floor or roof structure).

The footing is what bears the weight of the home instead of the concrete slab.

Slab-on-grade Pros:

  • Less maintenance. 

  • Pipes and electricity are built into the concrete.

  • There is no crawlspace to crawl in. 

  • While both can accommodate different flooring options, installing tile, carpet, wood floors, or laminate on a slab is easier. 

  • Protects from termites and other pests from the slab.

  • Monetarily less to construct. 

  • Concrete used to cost more back in the day. Now, concrete is much cheaper to purchase and install. 

  • They are very sturdy. 

Slab-on-grade Cons:

  • The concrete slab sucks in moisture.

    • Concrete is porous. Think of it like a sponge when it’s exposed to water.
  • More exposure to flood damage.

  • A concrete slab is prone to cracking. 

    • This is due to variations in weather and moisture. While concrete is strong, variations in moisture will cause portions to expand and contract.
  • Fewer options for home remodeling. 

    • Pipes are sealed in concrete when the slab is installed. You would have to take out the concrete and repouring later. 

So who do you place your bet on as the winner? It’s not for us to decide. You have the power to make that decision. 

Hopefully, these foundation comparisons have helped you. As we said before, these foundations both have their costs and benefits. When it comes down to it, there is no poor foundation–unless constructed poorly. Both are capable of supporting your home. 

Do you still have questions about these foundations? Is it still unclear what type your home has? Call Dalinghaus Construction at 877-260-9227. And while both foundations are good and do the same thing, you may still have concerns about your home. Schedule a free home evaluation today!

Read more: Lift & Stabilize Of A Slab Foundation in Fullerton

WRITTEN BY

Brian Dalinghaus

Brian is one of the Co-Founders of Dalinghaus Construction. He has been in the foundation repair industry since 2005. During his career, he has been associated with helping over 4,000 homes and structures throughout California and Arizona.

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