Measurement conventions

Today, the majority of bills of quantities are produced using proprietary software packages, each system having its own format for inputting dimensions and formulating descriptions. However, in order to fully understand and appreciated the potential problems in the measurement process a thorough knowledge of measurement conventions is essential.

Measurement is not just used by the quantity surveyor during the bills of quantity stage, but also during measurement and preparation of interim valuations and the final account. The traditional approach to measurement involves starts with recording dimensions on traditional dimension or 'taking off' paper.

The table below illustrates traditional dimension paper, it comprises A4 paper, either printed on 1 or both side, with 2 rows of identical columns.

These columns are referred to as:

• column 1 - the timesing column;  this column is useful on the occasions where there are identical or repeat items;
• column 2 - the dimension column; this column is used to record dimensions;
• column 3 - the squaring column; this column is used to record the computed quantities; and
• column 4 - the description column; the widest column this is used to compose the description of the measured items, in accordance with NRM2. This description will appear in the final bills of quantities.

Finally, the right hand side of the dimension column is reserved for what is referred to as; the waste calculations. They're not waste at all really, they are the 'workings out' behind the figures entered into column 3.

One of the most important disciplines for a quantity surveyor to develop is to 'sign post' or annotated the dimensions so that other people can easily see where and how the dimensions have been calculated. A well signposted set of dimensions can save a lot of time in circumstances where work has to be re-measured at the final account stage.

When taking off quantities in accordance with NRM2 the units of measurement will be: cubic meters, square meters, linear meters and numbered items. In addition, there are some items that are required to be recorded as items, which are descriptions without a quantity, for example, testing drainage.

When recording dimensions on the taking off paper the order in which the dimensions are recorded is always, length, width and depth as noted in the table.

One of the cardinal rules when measuring quantities is to always use ink; never pencil. It may be tempting, particularly if learning the process to use pencil, for easy of correction, however this can cause embarrassment if the accuracy of the dimensions are called into question at some future date. If an error is made during the measurement process then there is a procedure that should be followed: