Last edited 26 Feb 2019

What does in situ mean?

In situ (also referred to as insitu or in-situ) is a Latin phrase that is commonly used in the construction industry to mean ‘on site’, ‘in place’ or ‘in position’. It refers to work which is carried out on the construction site itself, often in the finished position, as opposed to in an off-site location as with prefabrication or pre-assembly techniques.

The most common use of the term 'in situ' is in relation to concrete, with components such as a slabs, beams and piles being described as ‘cast in situ’ to distinguish them from precast concrete components, that are manufactured off site.

Generally, in situ construction techniques tend to be more labour- and time-intensive, however, they are more flexible in response to changes that may arise on site. Prefabricated components, in contrast, must be designed in detail in advance, with limited scope for changes once they have been manufactured.

In situ can also be used to refer to in situ testing, for example, tests carried out on site to determine the density or shear strength of soils. For more information, see Insitu testing of soils.

Also, in the context of soil, in situ can refer to soil which is still in its original condition and that has not been ‘cut’ from one area of a site and ‘filled’ in elsewhere.