Craft Quantities
Plan & Takeoffs

By trade

Glazing calculators

Glass is one of the few materials whose weight decides how it is installed. A unit that two people can carry and a unit that needs a lifter are separated by a few millimetres of thickness, and that line — not the area — is what changes the programme, the access and the cost.

  • 27Calculators
  • 2Parts of the site

How glazing is measured

Square metres for the glass, kilograms per unit for handling, and linear metres for gaskets, spacers and frames. Openings are counted rather than measured in area, because every one of them carries a set of fixed items whatever its size.

What gets left off a glazing order

  • The rough opening allowance: a unit that fits the hole exactly does not fit at all once packers and tolerance are included.
  • Setting blocks, packers and the sequence they go in, which decide whether a sealed unit lasts or fails at the edge.
  • Access and lifting for anything above ground level, which is usually a bigger line than the glass.
  • Perimeter sealing and the movement it has to accommodate, measured around every opening rather than over the façade.

Job takeoffs1

Where glaziers meet the rest of the job: each runs one of these calculators, with every other trade in the same job beside it.

Comparisons6

Two ways of doing the same work, weighed against each other.