Schedule of Rates in Construction: How to Prepare, Price, and Use an SOR for Tendering

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A facilities management contractor tendered for a three-year term maintenance contract covering a portfolio of commercial buildings in central Manchester. The contract was priced on a Schedule of Rates — a document listing every likely maintenance activity with a unit rate against each one. The contractor priced each rate carefully, built in realistic overheads and profit, and submitted a competitive tender. The contract was awarded.

In the first six months, the work distribution looked roughly as expected. Minor repairs, planned maintenance visits, small plumbing jobs. Each item measured against the SOR, each invoice calculated by multiplying the quantity of work by the agreed unit rate. The commercial model was working as the contractor had planned.

Then the client instructed a significant drainage clearance programme across twelve buildings — a reactive programme triggered by persistent blockage problems that had been identified during the routine maintenance visits. The drainage clearance item in the SOR had been priced at a rate the contractor calculated assuming it would represent perhaps five percent of the total contract value. Over the next four months, it represented thirty-eight percent.

The rate itself was not wrong. It covered the direct cost of the work and a reasonable margin at the volume the contractor had assumed. At nearly eight times that volume, the economics of the rate changed completely — the supervision cost per unit increased because the drainage crew needed more coordination than the rate had allowed for, the plant hire utilisation was lower than assumed, and the contribution to head office overheads from this item alone was being diluted by the volume. The contractor finished year one of a three-year contract having lost money on the item that represented more than a third of its turnover.

The lesson was not that the SOR format was wrong for this contract. It was the right format — the scope was genuinely variable and the BOQ approach would not have worked. The lesson was that pricing a Schedule of Rates requires a different discipline from pricing a BOQ. When quantities are unknown, the rate has to work at multiple volume levels — not just the one the contractor assumed when they sat down to price the tender.

What a Schedule of Rates Is and Why Construction Uses It

A Schedule of Rates is a contract document that lists items of work with a unit rate against each one but without any stated quantities. The client and contractor agree the rates at tender stage. Once the contract is running, work is instructed, measured as it is completed, and paid by multiplying the actual quantity by the agreed SOR rate. The total contract value is not known at the time of award — it emerges from the actual volume of work instructed and carried out.

The reason the construction industry uses the SOR format — rather than always using a BOQ with measured quantities — is that for certain types of work, the scope genuinely cannot be quantified in advance. A term maintenance contract covering reactive repairs across a large asset portfolio does not have a predictable scope. An infrastructure maintenance programme covering roads, drainage, and structures responds to conditions on the ground rather than a predetermined list of activities. An early works contract starting before the full design is complete cannot be priced against quantities that do not yet exist.

For all of these situations, the SOR provides a structured commercial framework that allows the work to proceed, the contractor to be paid fairly for what they complete, and both parties to manage cost transparently against pre-agreed unit rates rather than renegotiating prices every time a new piece of work is instructed.

The types of construction work most commonly priced on a Schedule of Rates:

•       Term maintenance and facilities management contracts: Reactive maintenance, planned preventive maintenance, and minor works programmes where the volume and mix of activities changes with asset condition rather than a fixed programme

•       Framework agreements: Long-term contractor appointment arrangements covering multiple projects over several years — individual call-off orders priced using framework SOR rates

•       Infrastructure maintenance: Highway maintenance, drainage, structures, and utilities works where the scope is driven by inspection findings and network condition rather than a designed project

•       Early contractor involvement contracts: Where the contractor is appointed before design is complete and the scope is defined progressively — SOR rates provide the commercial basis for pricing work packages as they are issued

•       Measured term contracts: Formal contract arrangements — sometimes using JCT Without Quantities or NEC Option E — where all work over the contract period is valued against a pre-priced schedule

Schedule of Rates vs Bill of Quantities — The Key Differences

The BOQ and the SOR are the two primary pricing documents used in construction tendering — and understanding the difference between them determines which is the right instrument for any given project or contract. The distinction goes deeper than simply whether quantities are included or not — it affects where the risk sits, how payment is calculated, and how variations are valued throughout the contract.

The contractor pricing risk row in that table is the one that catches most contractors out on their first significant SOR contract. When pricing a BOQ, the QS receives quantities from the client's quantity surveyor and prices rates against them — the risk is whether the rates are competitive and accurate, not whether the quantities are correct. When pricing a Schedule of Rates, there are no quantities to price against. The contractor must decide what rate to apply to each item knowing that the volume of that item could be anything from negligible to dominant. The drainage clearance contractor in Manchester priced a rate that was commercially sound at low volume. The SOR gave the client the contractual right to instruct that item at any volume — and the rate had to work at all of them.

How to Build Up a Unit Rate for a Schedule of Rates

The unit rate in a Schedule of Rates is not just a price — it is a commercial position. It covers every cost associated with completing one unit of that work item, including a contribution to overheads and a profit margin, at a level that remains viable across the range of volumes that item might represent in practice. Building up rates correctly is the skill that separates contractors who make money on SOR contracts from those who discover the problem in year two.

The Overhead Recovery Problem at Scale

The most subtle pricing risk in a Schedule of Rates is the overhead recovery assumption. When a contractor builds overheads into an SOR rate, they are assuming that this item will contribute to overhead recovery in proportion to its share of the total work. If the item ends up representing a much larger share than expected, the overhead recovery per unit may look adequate — but the absolute overhead recovery across the whole contract may still be insufficient because the total contract value has not grown proportionally with the volume of this one item.

This happens most often on items where the rate is kept low to win the contract — competitive pressure drives the rate down on high-profile items that the client scrutinises most carefully during tender evaluation. Those same items, if instructed at high volume, end up cross-subsidising the contract's overhead recovery without delivering the margin the contractor assumed was built into the higher-rate items that were instructed at lower volume than expected.

What a Schedule of Rates Document Contains

A well-structured Schedule of Rates document goes beyond a list of items and rates. It contains the commercial and technical framework that both parties need to administer the contract correctly throughout its life — measuring work accurately, pricing variations that are not in the original schedule, and settling the final account without dispute.

The key sections every SOR document should include:

•       Preamble and general conditions: Defines what the rates include and exclude — whether plant, supervision, and small tools are deemed included in all rates, or priced separately — this section prevents the most common SOR disputes

•       Daywork schedule: Rates for labour, plant, and materials on a time and materials basis — used when work cannot be measured against the standard SOR items — typically expressed as a percentage addition to published daywork schedules

•       Measured work items: The main body of the SOR — items grouped by trade or work type, each with a unit of measurement, a brief description, and the priced unit rate

•       Provisional and star rate items: Items where the rate is not yet agreed — either provisional rates subject to negotiation or star rate items to be priced when the scope of that work is defined

•       Percentage adjustments: Some SOR contracts allow the contractor to apply a percentage addition or deduction to a published standard schedule — such as the PSA Schedule of Rates — rather than pricing individual rates from scratch

•       Escalation provisions: For contracts running longer than eighteen months, the mechanism for adjusting rates annually based on published indices — typically BCIS labour and materials indices

Using the SOR During the Contract — Valuation, Variations, and Final Account

Once the contract is running, the Schedule of Rates becomes the commercial reference for everything — monthly valuations, variation pricing, and final account settlement. A well-maintained SOR makes all three of these processes straightforward. An SOR that is poorly administered creates disputes at every stage.

Monthly Valuation Against the SOR

Each month the contractor measures the work completed during the period and applies the relevant SOR rates to calculate the valuation. The measurement must be done carefully — the preamble defines exactly what is included in each rate, and any attempt to claim separately for items the preamble says are included in the rate will be challenged by the client's QS. The measurement sheets, showing the location, description, and quantity of each item claimed, are the primary supporting document for the monthly payment application.

The client's QS checks the measurement against site records — visit reports, photographs, job cards, or whatever the contract's quality and monitoring requirements specify. Discrepancies between the contractor's measurement and the client's site records are the most common source of payment disputes on SOR contracts. The contractor who maintains clear site records, matched to SOR items and supported by evidence of completion, is the contractor who gets paid accurately and promptly.

Pricing Variations and New Items

When the client instructs work that is not covered by an existing SOR item — a new activity type, a specification requirement not anticipated in the original schedule, or a location with conditions that make the standard rate inapplicable — a new rate must be agreed. The SOR preamble should define the method for agreeing new rates — usually by reference to the build-up of the nearest comparable SOR item, adjusted for the differences in scope, materials, or method.

This is where the quality of the original rate build-up matters commercially. A contractor who can produce a transparent rate build-up for every item in the SOR — showing materials, labour, plant, overheads, and profit separately — is in a strong position to negotiate new rates based on the same methodology. A contractor who priced the SOR as a single number without a documented build-up has no reference point for the negotiation and will find the client's QS driving the new rate to the lowest defensible level.

The SOR is the commercial foundation for every variation on a term or maintenance contract. For a detailed guide to how variations are raised, valued, and managed throughout construction — whether the contract is priced on an SOR or a BOQ — see our article on Variation Orders in Construction: A Practical Guide.