Quote terms explained
What are preliminaries on a building quote?
Preliminaries, or prelims, are the costs of running the site rather than building anything: scaffolding, skips, site welfare, supervision, insurance, small plant, protection and cleaning. Estimators typically put them at 5 to 15% of the building cost, about 10% on a typical job. Some builders list them as a line, some spread them through their prices, and some leave parts of them out.
What prelims usually cover
| Item | Typical price | Notes |
|---|---|---|
| Scaffolding, one elevation | £450 to £800 for 6 to 8 weeks | Then roughly £15 to £30 a week; a single storey often needs less |
| 8-yard skip | £240 to £360 each | A road permit adds £15 to £60; London costs more |
| Site toilet | £15 to £30 a week | A welfare cabin is £60 to £150 a week |
| Supervision, insurance, small plant, protection, cleaning | 5 to 15% of the net building cost | About 10% on a typical job; higher in London |
Ranges from the Estiquote unit rate book (September 2026), drawn from Checkatrade, MyJobQuote, GigLoo and published builder guidance. See the builder's estimate tool for every rate and source.
Why prelims trip up quote comparisons
One builder shows £6,000 of prelims on a separate line. Another shows none, because the cost is spread through the other sections. A third genuinely leaves out scaffolding and skips, which you will pay for later. All three totals look different for reasons that have nothing to do with value. Ask each builder: "Are scaffolding, skips, welfare and supervision included, and where?"
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