Construction variations: when a variation is justified, and how to build a BOQ that leaves little room for one
Construction variations are works that were not in the contract, or that were done in a quantity or a way different from what the contract set, and so are paid on top of the contract sum. Some are fully justified: the client changed a drawing, the ground turned out different, an authority added a requirement. Others are born from an incomplete bill of quantities (BOQ) or from an unclear item description. This page explains it from the client's side: when a variation claim is justified, and how to build a bill of quantities that leaves little room for one. I have experience in quantity takeoff and in pricing variations on both sides of the table, at a main contractor and with site supervisors.
When a variation is justified, and when it is already in the price
The first question in any claim is not how much but whether. The table sums up common situations. It is general, and in every case what decides is the wording of the contract and the specification.
| Situation | Variation? | Why |
|---|---|---|
| The client added a room or changed a finishing material | Usually yes | A change in scope |
| In a measured contract, the actual quantity is larger than the quantity in the BOQ | Not a variation, a quantity update | The unit price stays, and the quantity is paid by measurement |
| Work that appears in the drawings but not in the BOQ | Depends on the contract | The most common source of disputes |
| Ancillary work: cleaning, pumping out rainwater, protecting finished work | Usually not | Included in the unit rates or in the overheads |
| Ground different from what the soil report described | Possibly | A change in conditions that were not known |
| The contractor chose a more expensive construction method | No | The means of construction are the contractor's responsibility |
Lump sum or measured: the difference that decides most variations
In a lump-sum contract the price is fixed for a defined scope. The quantity risk is on the contractor: if he calculated less plaster than was needed, that is his problem, and a variation exists only when the scope itself changed. In a measured contract (a remeasurement contract) the unit rates are fixed, and payment is for the quantity done and measured. Here the quantity risk is on the client, and an inaccurate bill of quantities shows up in the final account. Put simply: in a lump-sum contract people argue about the scope, and in a measured contract they argue about quantities and about items missing from the BOQ.
A short example: a measured BOQ lists 1,000 m² of internal plaster, and 1,080 m² were actually measured. The difference, 80 m², is paid at the same unit rate, and it is not a variation. On the other hand, if the client decided on thermal plaster instead of ordinary plaster, that is a new item with a new price, and so a variation. In the same project under a lump-sum contract, the extra 80 m² would have stayed at the contractor's expense, and only the change of plaster type would have earned an addition. Hence my recommendation: before choosing the type of contract, check how complete the drawings really are.
How to build a BOQ that reduces construction variations
- A full item description: material, thickness, layers, and what is included. A "roof waterproofing" item with no layers is an invitation to an argument.
- "The price includes" in every chapter, with a reference to the General Specification for building works (Israel's inter-ministerial specification) and to the particular technical specification. Why the specification matters is on the page technical specification before pricing.
- Option items: work that is likely to be needed gets a line in the BOQ, even with a small quantity, so that it has a competitive price from the tender.
- Daywork: a rate per labour hour and per plant hour, for small jobs that are hard to measure.
- A gap check: a comparison between the drawings, the specification and the BOQ, and a gap sheet before the BOQ goes out for pricing. The method is on the page professional bill of quantities.
- Interfaces between contractors: who cuts the chases for the building services, who closes them afterwards, who repairs.
- Quantities checked twice, so that a measured contract does not overrun by much.
An example: what a forgotten item costs
As an illustration, a waterproofing item of 400 m² that did not make it into the BOQ. In the tender, with several contractors competing, say the price would have been 100 shekels per m², that is 40,000. As a variation, without competition, a contractor may ask for 125 shekels per m², that is 50,000. The difference, 10,000 shekels, is on one item alone. In a BOQ of hundreds of items, a few items like this are already a significant part of the project's reserve. The numbers are an illustration, and the principle does not change: a variation is priced without competition.
My rule: every line in the gap sheet that is closed before the tender is a variation that will not come. An hour of checking before the tender costs far less than months of argument after it.
The best way to reduce construction variations is a full quantity takeoff, already at the tender stage. A quantity surveyor who flags in advance what is unclear in the drawings reduces the number of surprises during construction.
Frequently asked questions
Can a contractor claim a variation for work that is in the drawings but not in the BOQ?
It depends on the wording of the contract: some contracts say the drawings prevail, and some say the BOQ prevails. This is not legal advice, and in a dispute it is worth checking with a lawyer.
What is a variation order?
A written instruction from the client or from the supervisor to make a change, also called a change order. It is the basis for paying construction variations, and without it it is hard to prove that the work was ordered.
Does a lump-sum contract prevent variations?
It reduces them; it does not prevent them. A change in scope is a variation in a lump-sum contract too. How this works in the account is explained on the page interim payment application.
Who helps build a BOQ like this?
A quantity surveyor for construction projects who also knows the contractor's side knows where variations hide, and builds the BOQ so that they have a price in advance.
Have a project? Tell me briefly what the project is and what already exists. When the project is a good fit, I usually reply with focused questions and a written quote.
Contact me for a quote* Created with AI for marketing, for illustration only. Not reviewed by Yaakov Avital and not professional advice. Every project must be checked on its own by a professional quantity surveyor and an engineer.