Why Install a Pier and Slab Subfloor?
Posted on: 16 January 2020
If you need to lay a concrete slab subfloor on a build, then you have to choose the type of slab to use. In some cases, a simple slab on the ground gives enough support; however, this isn't always the case.
Ground conditions dictate what works and what doesn't here. In some cases, it's better to lay a more advanced reinforced solution, like a pier and slab floor. How does this option work and what are its benefits?
What Is a Pier and Slab Subfloor?
Like any slab foundation, this option uses an area of concrete to create a level and secure base for a build. However, the concrete isn't the only means of support.
These subfloors get extra support from piers which are driven into the ground around the slab area. Your contractor makes holes in the ground for the piers. They then fill these holes with concrete, steel or wood to create the actual supports.
Once the piers are in place, you lay the concrete to create the slab. This attaches to the piers. You usually leave some space between the concrete and the ground in this kind of build.
What Are the Benefits of Pier and Slab Construction?
A foundation slab can only do its job if it has its own support. If the ground under the slab can't take its weight or will move over the years, then the concrete could move in turn or start to crack. Once this happens, it is less able to support a building.
If the ground you're building on isn't stable, then you can't just lay a slab on top of it and hope for the best. For example, reactive soil is more likely to move over the years. Moisture may affect its stability, or it may be so unstable that it is liable to larger movements like subsidence collapse.
A pier and slab structure works well on reactive or unstable ground. The piers go deep into the earth. They give the slab additional support. Even if the ground under the slab were to move, the concrete stands a better chance of staying in place and intact because the piers hold it up as well.
Plus the gap between the slab and the ground adds stability to the build. This gap helps deal with problems like soil expansion. If soil were to increase in volume, it would simply fill the gap rather than putting pressure on the slab.
To learn more about concrete slabs, ask your contractor for advice.
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