Bolt and holding-down bolt mass

What it calculates

• Barrel mass: length × π/4 × d² × 7 850 kg/m³
• Anchor or plate washer mass: length × width × thickness × 7 850 kg/m³
• Nuts and washers per bolt, using the numbers you enter
• Mass per bolt, total kilograms and tonnes, and the number of bolts off

How to measure it, step by step

1. 01

   Record the job and the drawing

   On Project, enter the job, the drawing and its revision.

   Why: Bolt schedules change with the foundation drawings. The record has to say which drawing it measured.

2. 02

   One line per bolt type

   On Bolts, pick the size from the list, then enter the number off and the barrel length in millimetres.

   Why: Bolts of the same size and length weigh the same, so one line covers all of them. Barrel mass is length × mass per metre of the bar.

3. 03

   Add the anchor plate

   If the bolt has an anchor plate or a plate washer, enter its length, width and thickness in millimetres.

   Why: A 100 × 100 × 10 mm plate adds 0.785 kg to every bolt, more than the nuts. Leaving it out understates the delivery weight.

4. 04

   Enter nuts and washers per bolt

   Enter how many nuts and washers each bolt carries. Holding-down bolts often have two nuts, one for levelling and one for locking.

   Why: The source template ignored these numbers on every size except M6, so double-nutted bolts were under-measured.

5. 05

   Read the totals

   Bolts gives kg per bolt, the total in kg and tonnes, and the number of bolts off.

   Why: Holding-down bolts are often billed by number but bought by mass. The mass is what you check the supplier's delivery note against.

Measuring rules

Number or mass

On a SANS 1200 H contract, holding-down bolts are scheduled per tonne or by number, with a separate item for each diameter, size and shape. The rate covers the bolts complete with nuts, washers, threading, anchor plates and frames as drawn (clause 8.3.6). Erection bolts get one item for each grade and type (clause 8.3.4). Where many identical articles are measured by mass, the schedule states the number and the mass of each (clause 8.1.2). This workbook gives you both.

Barrel at nominal diameter

The barrel is taken as the full shank at nominal diameter. The thread makes a real bolt slightly lighter. For measurement, ignore it.

Nut and washer masses

The nut and washer masses are carried from the source template. They are in the range of standard metric hexagon nuts and plain washers, but they have not been checked against a supplier's table. Confirm them before you rely on them.

Standards behind it

Measure to the document your contract names. Clause numbers are given only for the SANS parts read in full, and the wording is paraphrased: read the clause itself in your copy. Each card says how far that reference was checked.

More on which standard applies when: measuring standards for South African construction.

What we fixed in the source template

This workbook is rebuilt from a contractor template that was in use. These are the errors it carried, and what each does now.

• Only the M6 row multiplied nut and washer mass by the number per bolt. Every other size added one nut and one washer whatever you entered. All sizes now use the numbers.
• The date was =TODAY(), so the record changed every time the file opened. It is now a typed date.
• Barrel masses are now calculated from the diameter instead of typed.
• The sheets were named for a past job (Reagents, Thickeners) and two were empty. They are replaced by one bolt sheet.

Planning-stage quantities, not a final account or a quote. Check every quantity against the drawings and the bill’s preambles. General guidance, not professional or engineering advice.

Reviewed by Aidan Koetaan MBA PMP, quantity surveyor and construction project manager.