There are three kinds of foundations – Basement, Crawlspace, and Concrete slab foundations. A stem wall is a concrete slab foundation. This structure attaches the wall of a building to its foundation. Stem walls are mostly made with rebar and concrete and are supportive structures. They help to create a firm basis when constructing a building. Furthermore, they also help to reduce the possibility of damage to the materials being used to construct the vertical walls.
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Why are stem walls more common in the USA?
Five foundations are common while constructing buildings in the USA. Stem walls are the most significant part of one of them. Stem walls are connected to a concrete footing and can have the height of a crawl space or a few feet tall. They have to be properly constructed as they carry a lot of weight. Specialized companies can build these.
In the USA, stem walls are most common in the South, California, the Northwest, and Texas. Stem walls are used to construct buildings that have both vented and unvented crawlspaces. If you live in a zone that is more earthquake-prone, the architects will most likely suggest using stem walls to build your home.
But in the Midwest, Northeast, and mid-Atlantic, stem walls are not very common. This is because the houses there have full basements. Stem walls are not commonly found in coastal areas where buildings rest on piers so that they stand above flood levels.
How does a stem wall work for a house?
In the USA and Canada, this is the most used type of structural footing. It is a short wall that connects the vertical structures (which bear the load) and the foundation of the structure. The stem walls sit on top of the ground. These walls help to shift the load from the superstructure to the flooring, and then this load is distributed over the entire foundation area.
Stem walls are indicated on the plan and engineers have to calculate how big they have to be and how much rebar that they have to contain.
Benefits of monolithic slabs vs. stem walls
Home builders in the US choose between two very different types of foundation – stem walls and monolithic slabs. Read the benefits of having each foundation to understand their characteristics.
Important benefits of stem walls are:
- Stem walls make a structure more appealing and look grand. This is because they help to elevate the structure.
- Stems walls are more accommodating as it is possible to build them at divergent heights. This is important to adjust to differing site ground elevations.
- Stem walls are more solid. They transfer the superstructure’s load to the foundation, which then distributes the load on its area. This can be important in areas that have weaker undergrounds.
- Since stem walls have an elevated base, they protect the structure from natural hazards like floods.
- You will not need a mechanical lift station if you want any septic system to drain. One can increase the height of stem walls so that gravity can do this work. It also makes it easier to repair these systems later on.
- Stem walls provide easy access and therefore, electrical and mechanical issues involving wiring and plumbing can be done easily.
Important benefits of monolithic slabs are:
- Once steel and fiber mesh is added, the monolithic slabs become very strong.
- In comparison with stem walls and other foundations, it takes a lesser amount of time to build monolithic slabs. For putting monolithic slabs, one does not need to dig out the soil and this saves a lot of time.
- Monolithic slabs can be used even in places where the soil is loose or of poor quality. This becomes possible when post-tensioning is added. In some locations, ground studies are done to find out what the best foundation is for your home.
- Monolithic slabs have uniform stability and medium consistency.
Why do stem walls fail?
Regardless of how good the construction is, after a considerable amount of time, they are bound to fail. The walls will eventually crack and crumble. This largely happens because moisture oxidizes the rebar and makes it rust. The cracks can develop both horizontally or vertically. A concrete stem wall is prone to erosion and concrete spalling too. In addition to that, the galvanized tie-down straps inside the stem walls also fail because they rot over time. And if you repair a stem wall, it will fail again. The reason is you replace rebar with rebar as most of the time contractors put oxidized rebar while they stem wall.
Stem Wall Foundation Repair
If you reside in a building having stem walls, it is good to know the basics about how they are repaired. Knowing what is the way to repair stem walls will help you while interacting with a construction and foundation repair company. There are three different types of repairs commonly done on stem walls – crack repair, underpinning, and seismic retrofitting.
- Carbon fiber crack repair
When you have to repair a cement fracture, carbon fiber wraps and carbon fiber staples are mostly used for it. This is because this can be done very quickly. Additionally, epoxy is added to carbon fiber before repairing, which makes it stronger than Kevlar.
- Underpinning
A building’s foundation faces a huge amount of stress or force. A foundation settlement is when a home settles or sinks due to the soil’s incapability of handling load. Underpinning alleviates more settlement and gets back the building to level.
- Seismic retrofitting
Seismic brace-and-bolted retrofitting can repair stem wall foundations after an earthquake. This repair strengthens the building and makes it prepared for any possible seismic activity.
Conclusion
Certainly, not all buildings that you see in the USA use stem walls to support building structures. But architects have designed many types of buildings that have stem walls as their support structure. Both residential and public buildings have stem walls to affix the walls to the foundation. As stem walls provided added protection and stability, they are even used in building manufacturing plants.
Sources
https://www.thisoldhouse.com/foundations/21015176/from-the-ground-up-house-foundations
