What’s better—a slab or a crawlspace foundation?

Grand Junction Real Estate Advice

Dave,

What’s better—a slab or a crawlspace foundation? We’re about to start looking for homes and we’re wondering if a certain type of foundation should be on our must have list. If we find a home that we love, but it has a less superior foundation model should we give it up? This might seem like a very specific question, but we want to make sure we’re investing our money in the right home! Thanks for your advice!

Sam and Katie, Grand Junction


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Sam and Katie,

Great to see you are really thinking this one out! The good news is that if your home is on a stem wall (crawlspace) or concrete slab foundation I think you will find that both are quality options. I don’t think that you have to rule one option out and the other one in, they will both serve the purpose of creating a solid foundation for your home. First a monolithic slab is typically 4-6 inches deep and made from concrete poured over compacted soil. It will have a thickened perimeter edge that can handle the weight of the load bearing walls. A stem-wall foundation is constructed with concrete footings and concrete walls that rise above ground level to provide a raised platform for placing the home’s ground floor leaving a void (crawl space) between the ground and the sub-floor of your home. Both of these methods have advantages and disadvantages.

Both of these methods have advantages and disadvantages.

Let’s take a closer look at a concrete slab foundation. The advantages are that a concrete slab is generally less expensive and quicker to build. They are also great for preventing pests and rodents from getting under the house. If you have a water leak, concrete will not rot or become compromised like a wood sub floor. A slab foundation will generally help insulate the home a little better and can lead to a decrease in your heating and cooling bills as it rests directly on the ground. And lastly slab foundations are typically closer to the ground and do not require steps at entry or exit doors and this can prove VERY convenient depending on your age. Some of the disadvantages can be that if not poured correctly they can be un-level and uneven in spots. The biggest concern for many home owners is that if you ever need to make any repairs, primarily with plumbing, that goes beneath the house, it can be very difficult and prove expensive to remedy as it will require removal of part of the slab to correct. Typically we see monolithic slab foundations in the Grand Valley where the soils are of good quality or we have a higher water table, as they prove more economical and are structurally very sound. 

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Stem wall foundations are the second most common foundation in our area and it too has positives and negatives. The biggest perceived advantage of a stem wall foundation with a crawl space is that if there are any required plumbing repairs (beneath the floor) then they are easily made and are typically not overly expensive because all the plumbing is easily accessible. They are also softer on your joints as your floors are all built over wood, not concrete. They are typically easier to design and build if the lot is un-level as the stem walls can vary in height making it much easier to work on a lot that has variable terrain. The overwhelming disadvantage to a crawl space, in my opinion, is moisture and the need for proper ventilation and monitoring. Moisture and crawlspaces don’t mix and often can lead to mold and mildew. When this happens it typically spells a big money fix. With a crawlspace it is imperative that you divert all moisture away from the house, so it does not penetrate the crawlspace. Even if you have diverted all water away, many times water will enter a crawlspace from your sprinklers or even one of your neighbor’s sprinklers or downspouts. It is very typical to see a stem wall foundation where the soils are bad or the ground is very uneven. 

As you can see, both have positives and negatives and more than anything it just comes down to price point and personal preference, however I will say that over the past 15 years I have seen far more issues related to crawlspaces than I have a slab foundations. If you decide to go with a stem wall foundation, you MUST monitor the crawlspace regularly to ensure there is no moisture present and ventilation is sufficient. Don’t shy away from either foundation, as both are solid and have areas where one is more desirable than the other, but definitely be aware of the pros and cons! I hope this helped a little. 

Dave Kimbrough
The Kimbrough Team

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