Craft Quantities
Plan & Takeoffs

By trade

Insulation calculators

Insulation is the trade where the quantity often follows from a target rather than from an area. You are not asked for a thickness; you are asked for a U-value, and the thickness that reaches it depends on the conductivity of the product and on everything else in the build-up.

  • 32Calculators
  • 2Parts of the site

How insulation is measured

Square metres at a thickness for boards and batts, bags at a settled depth for blown material, and linear metres for everything that seals the edges. A bag's coverage is quoted at a settled depth, which is not the depth it is blown to.

What gets left off a insulation order

  • Thermal bridging. Continuous insulation and insulation between studs at the same nominal depth do not give the same U-value, and the difference is not small.
  • Compression. Quilt squeezed into a shallower space loses performance roughly in proportion, and boarding over a loft is the usual cause.
  • The air barrier, which is a different product doing a different job, and without which the insulation underperforms whatever its depth.
  • Cutting waste in a rafter or stud void, where the material is cut to width and the offcuts rarely fit the next bay.

Job takeoffs24

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

Worked examples4

A real job estimated step by step, with this trade's steps counted.

Comparisons17

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

Planners3

Work this trade out from a space rather than from a job.