Building and construction: Footings systems

Audio interview with David Russell Jones

  1. What documentation is important at this stage?
The documentation that is important at the laying of the footing stage of the project are really any records that are going to assist in the verification of our quality control. Getting a project right in the ground is important for two reasons. One, it’s very difficult to go back and correct problems that we have in the ground and obviously the footing system has to support the building over its lifetime. So, a photographic record is always valuable but we will have a number of other documents to support that. The footings before they are poured would be inspected by a building surveyor or an engineer or even maybe both and their reports would substantiate that everything has been placed in accordance with the design.
  1. How would you ensure the footing comply with relevant building codes and principles?
To ensure the footings comply with relevant building codes and principles isn’t necessarily the role of the builder or project manager. The footing design is carried out by a structural engineer before the builder arrives on site and then it’s the responsibility of the project manager to provide that design. Often the site conditions that are encountered may be different to what was expected at the design stage. For instance in pier and beam footing construction the piers may have a provisional depth of two metres. The two metres would imply that the soil conditions were expected to support the building at that level. Often over a large site the soil conditions can vary quite considerably and while some piers may strike a firm foundation such as rock at two metres as we move across the site we may well find that that foundation falls away to a depth of five, six or even maybe seven metres. Once we get to six metres the conventional boring rigs tend not to be able to bore the piers and the original design may not be adequate for the increased length of the piers in which case they may need to be a larger diameter or they may need to be increased reinforcement in the piers.
  1. How would you ensure the footing comply with relevant building codes and principles?
To ensure the footings comply with relevant building codes and principles isn’t necessarily the role of the builder or project manager. The footing design is carried out by a structural engineer before the builder arrives on site and then it’s the responsibility of the project manager to provide that design. Often the site conditions that are encountered may be different to what was expected at the design stage. For instance in pier and beam footing construction the piers may have a provisional depth of two metres. The two metres would imply that the soil conditions were expected to support the building at that level. Often over a large site the soil conditions can vary quite considerably and while some piers may strike a firm foundation such as rock at two metres as we move across the site we may well find that that foundation falls away to a depth of five, six or even maybe seven metres. Once we get to six metres the conventional boring rigs tend not to be able to bore the piers and the original design may not be adequate for the increased length of the piers in which case they may need to be a larger diameter or they may need to be increased reinforcement in the piers.

1