While the term ‘concrete slabs’ might certainly be familiar to many people, the term ‘stumps’ might not be. Both are terms related to the foundation of a house – they are two methods in which the foundation of a house can be built. In the case of stumps, the foundation basically consists of concrete, wood or galvanized steel pillars which uphold the subfloor of a house (on which the rest of the house is built upon).
Stumps were the norm for foundations until the late 20th century. Following the advent into the 1980s however, concrete slabs gained popularity as a foundation style, and nowadays have become the predominant method of foundation building. The reason lies in the many disadvantages the stumps foundations pose, and in the relative advantages the concrete slabs foundations have over them.
Stumps require proper attention or maintenance, otherwise, the probability of a part of the house (or even the entire house itself) collapsing becomes real. Stumps can settle due to earth movement, or can rot if they are made of wood. In either case, the stumps have to be replaced or at least ‘packed out’ (i.e. moved to their original position) through house lifting in a process called restumping.
Restumping involves therefore the replacement or packing out of the stumps; a hydraulic jack is used for good house lifting to complete this.
The need of maintenance is not the only drawback stumps foundations have though; they also have poor insulation. By comparison, concrete slabs have much better insulation (and are therefore better suited to milder climates). Concrete slabs are also relatively cheaper. The reason behind this is that building the stumps, and not to mention framing the subfloor, is have more labour intensive work for house reblocking, and therefore much more expensive. Plus, given the poor insulation of stumps foundations, extra care and planning have to be put in to meet standards and regulations (which can be easily avoided in the case of concrete slabs foundations).
However, while stumps foundations certainly have many drawbacks, the fact that they are still acknowledged as a proper method of building foundations equals to the fact that there are instances where they win over concrete slabs foundations. Such an instance is when houses and buildings need to be built above the ground level. In this case, a concrete slab foundation becomes the expensive alternative, because filling the site to raise the concrete slab level is expensive. Therefore, under this circumstance, stumps foundations become the cheaper alternative.
Thus, while stumps foundations have certainly lost their popularity since the 1980s, they have not become obsolete as they still retain advantages under certain conditions. However, most of the time, concrete slab foundations have become the norm worldwide.