🇹🇴 Tonga · SMM7 · Work section
Preliminaries in a Tonga bill of quantities
In Tonga, the preliminaries section of a Bill of Quantities (BoQ) is measured to SMM7 — Standard Method of Measurement (Commonwealth practice). It covers 7 principal groups of work — site establishment — hoarding, site office, storage, sanitation through to site clearance and making good on completion — and is headed in the bill as "ELEMENT NO. 03 — PRELIMINARIES".
Preliminaries is one of the sections every Bill of Quantities (BoQ) in Tonga is built from. This page sets out what belongs in it, the unit each item is measured in under SMM7 — Standard Method of Measurement (Commonwealth practice), the local conventions that change the quantities here, and a worked example for a 150 m² house — plus the errors in this section that actually cost money on site.
What this section covers
- Site establishment — hoarding, site office, storage, sanitation
- Temporary services: water, power and their connection charges
- Contractor's supervision and site management for the contract period
- Plant and scaffolding held on site rather than used by a single trade
- Insurances, performance bond and statutory levies
- Setting out, survey and as-built records
- Site clearance and making good on completion
How each item is measured
| Item | Unit | Measurement rule |
|---|---|---|
| Site establishment | item | Priced as a lump sum for the whole contract, not measured against any quantity of work. |
| Supervision and management | week | Time-related: measured against the contract period, so a longer programme costs more even if the work does not change. |
| Scaffolding | item / m² | Either a lump sum for the building or measured on the elevation area it serves. |
| Insurances and bonds | item | A percentage of contract value, entered as a lump sum. |
| Temporary services | item | Connection charges plus a running allowance for the programme duration. |
Local conventions in Tonga
- —With no municipal sewer, temporary sanitation means hired units serviced on a schedule — a recurring cost across the whole programme, not a one-off.
- —A subtropical climate affects the wet-weather allowance: programme time lost to rain is a preliminaries cost, not a trade cost, and it is the single most common under-estimate in this section.
What goes wrong in this section
- —Preliminaries typically run 8–15% of contract value. A bill that shows 3% is not cheap — it means the cost has been buried in the trade rates where you cannot see or control it.
- —Time-related items scale with the programme. Every week of delay re-prices this section, which is why extension-of-time claims land here first.
- —Omitting preliminaries entirely and 'spreading it in the rates' makes variations impossible to price fairly later.
Get every section measured, not just this one
Upload your dimensioned drawings and get a complete bill of quantities (boq) in the SMM7 format, priced in TOP (T$), with every rate source-cited.
Generate my Tonga BoQPreliminaries — frequently asked
What goes into the preliminaries section of a bill of quantities in Tonga?
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Site establishment — hoarding, site office, storage, sanitation; Temporary services: water, power and their connection charges; Contractor's supervision and site management for the contract period; Plant and scaffolding held on site rather than used by a single trade; and 3 further groups of work. Under SMM7 each is described, measured in its own unit, and priced separately so the total is auditable line by line.
What units is preliminaries measured in?
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Site establishment in item, Supervision and management in week, Scaffolding in item / m², Insurances and bonds in item. Getting the unit right matters more than getting the quantity precisely right — a contractor can adjust a quantity, but cannot price an item measured in the wrong unit at all.
How is preliminaries different in Tonga from elsewhere?
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With no municipal sewer, temporary sanitation means hired units serviced on a schedule — a recurring cost across the whole programme, not a one-off.
What is the most common costly mistake in this section?
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Preliminaries typically run 8–15% of contract value. A bill that shows 3% is not cheap — it means the cost has been buried in the trade rates where you cannot see or control it.
How do I get this section measured for my own project?
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Upload your dimensioned drawings to Enormous Buildings. The bill is produced in the SMM7 format, grouped by section with preliminaries priced in TOP (T$), and every unit rate carries a source so a Tonga quantity surveyor can check it.