The structural weight of any structure or module is the total mass of the completed object minus anything which does not belong to the architectural plan. This does not include furnishings, persons or animals, stored items, water (except in architectural uses, such as a tuned mass damper), or added fixtures such as transmission antennae which do not belong to the design. It does include the interior walls and any paint or carpets which were envisioned in the architectural plan.

A finished building is never weighed. Figures of this kind come from the bill of quantities or the structural drawings, so they record what was specified, and a value for a building still going up is a plan rather than a measurement.

The material counts only where it does structural work. Reinforcement in a non-structural screed, cladding hung on a frame and decorative timber are outside these fields even though they are the same material.

Where a structure was extended or partly rebuilt, the figure belongs to whichever scope the source measured. A weight for the original building and one for the building today are different numbers.