Curious about concrete slab foundations? Great! RegionalFoundationRepair is at your service 24/7. In this guide, we cover common questions like:
- What Are The Different Types of Concrete Slab Foundations?
- What Are The Benefits and Advantages of Concrete Slab Foundations?
- What Are The Common Problems of Concrete Slab Foundations?
- What Are The Correct Conditions for a Concrete Slab Foundation?
For a quick pricing quote on concrete slab foundation repair or installation, tell us about your project in the form. We’ll get you connected with one of our foundation repair technicians in your city, or continue reading to learn about concrete slab foundations.
What Is A Concrete Slab Foundation?
A concrete slab foundation is a home foundation that consists of a large concrete pad poured directly on the ground where your home will sit. A slab is the only foundation style that doesn’t allow for a crawlspace or access to the underside of your structure, as the soil sits just below the concrete, and your flooring sits just above it. However, there is a slab-on-grade foundation variation that provides some under-home space.
To begin the construction of a slab foundation for a new home, we carry out the necessary ground preparation. This process includes minimal excavation and the removal of all of the organic material beneath the home construction site, which could cause problems with uneven settling down the road if left in the soil. We then lay down a layer of sand to act as a level bed for the concrete and improve drainage beneath your home.
Once the soil is prepped, we construct the mold for the slab and begin pouring the concrete. We always take great care to prepare and screed the concrete to minimize air pockets and unlevel sections across your foundation.
Some homeowners opt to add a stem wall and piers to slab foundations, but this option effectively changes the design. Raised homes on slabs poured on-grade are generally considered pier foundations.
Concrete slabs require reinforcement to maximize their load potential and ensure they can support your home. We typically use steel rebar to reinforce your slab foundation, as this is the most robust and reliable option for increasing your foundation’s structural integrity.
Once the slab is completely dry, framing and anchoring can commence.
Slab foundations are a very popular option for many builders, primarily because they’re very affordable. They require minimal excavation, so we can charge significantly lower costs for labor. Provided the climate is suitable for slab-on-grade construction, this is often the preferred building method.
Slabs also require the least amount of molding, can be set in just a single pour, and dry quickly. The total project time for slab construction will be less than any other type of foundation.
Lastly, concrete slabs are the simplest form of foundation construction. Of course, we always go the extra mile to ensure that slab foundations are appropriately set, are fitted with proper waterproofing materials, and won’t be prone to uneven settling in the future. Despite our attention to minor details, they are the most straightforward foundation to build.
No foundation style is perfect, and there are some drawbacks to building slab foundations. The biggest issue is generally working utilities into the foundation. Plumbing lines, air conditioning ducts, and even electrical wiring can be routed through your slab to minimize the expensive materials used and make your home more efficient.
Coordinating with utility companies before and during foundation construction can be a sticking point for some foundation companies. At Regional Foundation Repair, we use a 24/7 on-call project manager to maintain open communication, limiting any delays in the construction process. However, some other companies may be significantly delayed if they aren’t as communicative or proactive.
Additionally, weather can be a limiting factor when pouring slabs for house foundations. The concrete needs to remain dry as it cures, so rain and snow can both delay us in the construction of slab foundations.
What Are The Correct Conditions for Concrete Slab Foundations?
Slab foundations are ideal for warm and moderate climates. One of the biggest deciding factors for your foundation style is the frost depth, which is the depth to which the ground freezes in the winter.
Your utility lines and footings must be run below that level, which means slabs are inadequate in colder climates with deep frost lines. This foundation style minimizes costs and is perfectly adequate for utility line depth in areas where temperatures don’t usually dip below freezing.
Slab foundations are also best in locations where flooding isn’t expected. Properties near the water at low elevations tend to be prone to tidal, river, and flash flooding, especially during rainstorms in areas where there is a high water table.
Slabs are more suitable in these areas than basements and crawlspace foundations, but they are still prone to moisture problems, so they’re better options where flooding isn’t a severe risk factor.
What Are The Types of Concrete Slab Foundations?
There is just one primary foundation style that is a true slab, but a variation exists that some refer to as a slab foundation. We’ll discuss these below, along with two options we use for reinforcing your concrete slab.
Monolithic Slab Foundation
Monolithic slabs are the true slab foundation style. They are constructed on-grade, meaning we pour them directly on the ground after soil preparation and mold construction. “Monolithic” refers to the slab being one sheet of poured concrete, so there are no joints or gaps in the foundation once it has dried.
Monolithic slabs have no space between the concrete and the ground, so you won’t have a crawlspace or basement with this foundation style.
Stem Wall Slab Foundation
Some people refer to pier foundations with stem walls as slab foundations because a slab is still technically poured on-grade. When we construct a stem wall foundation, we first pour the concrete walls and concrete footings around the perimeter of your home, and then pour the slab inside the foundation walls once they have dried.
Stem wall slab foundations do offer a crawlspace, typically between one and three feet tall. This area can provide easy access for home inspections or utility repairs.
Slab Reinforcement Variations
Concrete is strong, but it requires reinforcement to support your structure and stand the test of time. We offer two variations for reinforcement: cable and steel rebar.
Cable reinforcement consists of tensioning cables running through the slab that can be tightened to keep your slab under compression once dried. Steel rebar is rigid steel that is set into the concrete before it dries to add strength from within the slab.
In addition to structural reinforcement, wire mesh can also be added to the concrete to prevent shrinkage cracks as the concrete sets.
What Are The Benefits and Advantages of Concrete Slab Foundations?
Slab foundations are very popular design choices, and for good reason. There are many benefits to opting for a concrete slab beneath your home.
Good Energy Efficiency
One of the most compelling benefits of a slab foundation is the energy efficiency you’ll enjoy. Crawlspaces and basement foundations may provide living or storage space, but their underground location makes them cooler, and the poured concrete or concrete block walls act as a more significant surface area for heat loss. Slabs have minimal contact with the ground and no under-home spaces where heat can be lost.
As such, homeowners with slab foundations will generally experience more comfortable indoor air temperatures. The increased efficiency of your slab will also mean lower costs for heating and cooling, which can be significant in the long run.
Fewer Moisture Problems
Homeowners with crawlspaces and basements frequently contend with water and moisture problems, but those with slabs experience very few. It’s still possible for moisture to wick through your concrete and settle between the slab and your flooring, but the risk is significantly lower than with other foundation styles. We generally install a vapor barrier on slabs to reduce the risk of water intrusion.
Moisture can contribute to indoor humidity and mold growth, which means a slab foundation will leave you less prone to these problems. The air in your living space is more likely to be free from airborne mold spores and uncomfortable humidity with a slab below your house.
Lower Risk of Pest Infestations
Crawlspaces and basements are also plagued with pest infestations, as insects and rodents are naturally drawn to damp, dark areas. Termites, carpenter ants, and other pests can gradually eat away at your home and leave you with structural damage over time. Pests can still enter through your other building materials above the concrete slab, but you run no risk of insects and rodents living beneath your house.
Minimal Flooring Issues
A single concrete slab below your structure means that the flooring throughout your house will be extremely sturdy and level, provided there is no severe structural damage or differential settling beneath the concrete.
Homeowners with other foundation styles will eventually experience creaking and slight slopes in their flooring, but slabs will never creak and will remain perfectly level unless significant shifting occurs.
Finally, concrete slabs are the most affordable foundation style. They require the least amount of ground preparation, excavation, and construction materials, so we always charge significantly less for slab construction than we do for pier and beam foundations, crawlspaces, and basements.
What Are The Common Problems of Concrete Slab Foundations?
No foundation style is perfect, and there are some drawbacks to having a concrete slab below your house. We’ll discuss the most compelling issues below.
No Under-home Storage
The biggest complaint most homeowners have with slab foundations is that they lack the additional living or storage space that a crawlspace or full basement would provide. A small crawlspace is possible with a stem wall slab design, but monolithic slabs have no under-home area.
Challenging to Access Utilities
The lack of a crawlspace beneath your house means that your utilities will either need to be run through your attic, as is the case with most HVAC ductwork, or through the concrete slab, which is a popular option for plumbing and electrical wiring.
As you can imagine, repairing utilities that have been routed through your solid concrete slab can be very challenging. Before a technician can perform the repair, we would need to use a jackhammer to break up the section of concrete safely to expose the damaged utility line. This is not only an invasive process but also an expensive one.
Additionally, issues with plumbing lines run through your walls generally become evident fairly quickly. Leaking pipes in your slab are much more challenging to detect, so the problem may persist for more extended periods. Ongoing leaks in your slab can drive up your water bills and contribute to differential settling beneath your slab, which can leave you with costly structural damage.
Prone to Cracking
Unfortunately, slab foundations are prone to cracking, even when we carry out construction responsibly and appropriately. Expansive soil and excessive rain can both pose issues with ground movement that has a more considerable effect on single-piece slabs than it would on piers. As such, slabs can be damaged by differential settling, especially in areas where the soil is predominantly clay.
Additionally, slabs sit directly on the soil at ground level, which is the most prone to expansion and contraction. Other types of foundations are set deeper in the earth and suffer slightly less movement.
Not Ideal for Flooding
Finally, slab foundations are generally better than crawlspaces and basements in areas where groundwater is very shallow or where flooding is a common occurrence. However, slabs regularly suffer damage when excess surface water interacts with them, and exposure to ground moisture in flooded areas can promote moisture problems and mold growth between your foundation and your first floor.
Slabs built on-grade are among the most common foundation types throughout the United States, especially in warmer or moderate climates where the frost depth doesn’t necessitate a deeper foundation. Slabs limit under-home moisture problems, mold growth, pest infestation, and water intrusion, but they are prone to cracking and structural damage from differential settlement.
Our foundation experts at Regional Foundation Repair specialize in reliable and affordable slab foundation construction, as well as foundation repair. Simply tell us about your foundation project or problem in our convenient contact form, and we’ll connect you with the most qualified foundation specialist on our team.