When it comes to foundation installation, the type of soil on site in Reading or any other location dictates what kind of foundations we use. However, unlike other groundworks such as drainage preparation and concrete laying, the excavation for foundations has a certain amount of unpredictability. Quite simply, we can have a reasonably good idea of what type soil lies beneath the surface, but there’s always the chance of a surprise. As genuinely local groundwork contractors, we have a good understanding of local soils, but we always have to operate with flexibility in mind.
Below, we have provided a brief guide to some of the most common soil types that we encounter in our work as groundwork contractors serving Reading, Dorking and the surrounding areas.
Rock – Rocks such as granite, limestone, shale, sandstone and hard solid chalk all have a high load-bearing capacity. In the best cases, we may only need to strip back and level off the rock to create a building platform. With impervious rocks, we install drainage features to handle water management
Chalk – As groundwork contractors, we commonly use strip foundations. When the chalk isn’t too soft, a width of 450mm is acceptable for low-rise buildings while the depth of the foundation installation must be below any frost action, usually 700mm. In cases with soft chalk, we excavate down until reaching a firmer level
Peat – Peat, as well as any loose waterlogged sand, make very poor subsoils for any kind of groundworks, be it foundation installation, drainage preparation or concrete laying. In some cases, our groundwork contractors can strip peat back to find adequate load-bearing ground at least 1.5m in depth
Gravel and Sand – When gravel, or gravel and sand subsoils, have a dry and compact nature, they usually work well with strip foundations. However, with high water tables and submerged gravel, the bearing capacity halves. Generally speaking, it remains important to keep these foundations in Reading as high as possible
Clay – The initial 900mm to 1,200mm of clay has a certain instability as it shrinks and expands depending on its moisture content. As such, we excavate to a minimum depth of 1m but can reach depths of 3m if there are, or were, trees in the vicinity. At these depths, the clay becomes more stable
Filled Ground – If sites in Reading have been previously excavated and then backfilled, our groundwork contractors generally need to dig down to a level below the fill. This ensures the appropriate support for groundworks like a foundation installation, drainage preparation and concrete laying.