Padstones (also known as Pad Stones) are structural elements primarily employed in masonry construction. Their key function lies in distributing concentrated loads arising from beams and, in some cases, extended lintel spans. Spreading this load over a larger surface prevents the force being directed over a limited area and causing overly high point loading, therefore mitigating the risk of localised failure within the wall material.
Beams and lintels are used as structural components that assist with managing loading throughout a construction. They allow architects to concentrate loads on areas designed to take them, enabling more fluidity in design relating to either floor space or aperture size. However, while you can transfer the force above the element across to the support columns it is resting on, it vital that these supports (often masonry walls) are able to bear the expected loads that they will endure. As such, the supports must transfer this force over a large area to better distribute this force. This is where concrete padstones come in.
Padstone Materials
Concrete padstones are most commonly manufactured from high density concrete, however, it is possible to use other elements such as steel spreader plates, engineering bricks, stone (hence the name ‘Pad Stone’) or poured concrete. The choice of material to use, and even the type of padstone to incorporate must be a carefully considered choice. The expected loading must be calculated (most commonly in Newtons per mm), along with the bearing capacity of the supporting element, and it’s also suggested that you consider the thermal efficiency of using different materials within the wall.
How Padstones Balance Loads
The concept of pad stones is also used in lower level point load balancing in the form of pad foundations. This method of managing these point loads across a larger surface area is ultimately the same. However, the general configuration and shape often varies depending on the application, substrate/soil conditions, and ground topography. Pad stones used in foundations could be square, rectangle, circular, or even stepped.
Padstone Sizes
Padstones are manufactured in a range of dimensions to cover all expected usage mentioned above. Padstones used in residential housing projects are most commonly between 100mm to 215mm in depth, with lengths ranging from 215mm up to 900mm.