What Is a BOQ, and Why a Contractor Who Hides It Worries Us

What a BOQ Is, in the Simplest Possible Terms

A BOQ, or bill of quantities, is the table that breaks a house down into priced pieces of work. Every line says what has to be done, how much of it there is, which material brand or grade it uses, the rate per unit, and the total for that line. The price of the whole house is nothing more than the sum of those lines.

If the drawings show you what the house will look like, the BOQ explains what it is made of and how it is being charged for. Drawings on their own cannot tell you the price per square metre of the floor tile or how many kilograms of reinforcing steel are in the slab. The two documents always have to travel together.

Plenty of owners building in Korat (Nakhon Ratchasima) or Roi Et receive a single sheet of paper that says "construct house as per drawings, lump sum 4 million baht". That is a price with no BOQ behind it, and it is the starting point for most of the trouble that follows. This matters doubly for foreign owners: foreigners generally cannot own land in Thailand, so the house is usually built on a plot held by a Thai spouse, a Thai company or a long lease, and the construction paperwork is often the clearest record tying the money you spend to the work you actually receive.

What a Usable BOQ Has to Contain

A BOQ that works in practice is split into trade sections following the order of the build: site preparation, piling and foundations, structure, roof, walls and plaster, floor finishes, ceilings, doors and windows, sanitaryware, electrical, plumbing and paint. Each section runs to several lines, and each line carries a clear unit of measure such as square metres, cubic metres, kilograms or sets.

A good line names the material precisely enough that a stranger could go out and buy it: 60 by 60 centimetre glazed porcelain floor tile with the brand and model stated, not simply "grade A tile". For anything you have not chosen yet, the line should appear as a provisional allowance with a rate per unit attached, so that you know in advance what upgrading to something more expensive will cost you.

The foot of the table should separate materials, labour, site overheads, profit and VAT rather than rolling them into one figure. A contractor who runs a proper business can produce that breakdown without any difficulty, because those are the same numbers used internally to keep costs under control.

How a BOQ Lets You Compare Contractors Fairly

The first benefit shows up immediately, when you compare quotations. If three contractors price the same house without a BOQ, all you see is three numbers and no way of knowing why they differ. If all three price on the same drawings with a BOQ attached, you can see exactly what the cheapest one has left out and what grade of material it has assumed.

Very often a quote that comes in 200,000 baht below the rest does so by leaving out the piling, leaving out the paintwork, or using less steel than the structural drawings call for. Without a table you can read line by line, those omissions do not disappear. They come back as extra charges halfway through the build, when you have very little room to argue.

The method that genuinely works is to have the designer or the home-building company prepare one master BOQ with every item listed, then send that same table to each contractor to fill in with their own rates. Once the scope is identical for everyone, the differences between the totals finally mean something.

A BOQ Controls Variations and Progress Payments

Almost every house changes while it is being built. The owner wants the bathroom a little larger, a different tile, or a few more power points. When a BOQ exists, pricing those variations is simple arithmetic, because the rate for every unit of work has already been agreed. There is no fresh negotiation each time something moves.

The benefit people overlook is inspecting progress claims. When the contractor reports that the structural stage is finished and asks to draw the next payment, you or your inspector can hold that claim against the BOQ and check what that section actually included and whether all of it is done, instead of walking the site and forming a general impression that it looks about right.

Banks that lend against construction also use the BOQ, both when approving the loan and when releasing each drawdown. If you intend to borrow, having no BOQ will slow you down from the day you submit the application onwards.

The Tricks in a BOQ You Need to Spot

The first trick is the lump-sum line: "electrical works, whole house, 150,000 baht", with no count of outlets and light points, no cable sizes and no brand for the consumer unit. With no detail recorded, a quiet downgrade in specification is impossible to detect later, and every extra light point gets priced on the spot at whatever figure suits the contractor.

The second trick is the phrase "to standard" or "or equivalent", with no word on whose standard is meant. Material described as equivalent has a habit of turning out cheaper every single time, so insist that at least one brand and model is named as the benchmark. The third trick is the item that is simply absent: no line for carting spoil off site, no line for testing the services, no line for the final clean before handover. Each of those will return later as a variation.

The easiest way to check is to walk through the drawings room by room and ask, for every single thing in that room, which line of the BOQ it sits on. If you cannot find it, nobody has priced it.

What to Do When a Contractor Will Not Show You the BOQ

The reasons you hear most often are that the owner will take the rates to a rival and have them undercut, or simply that the contractor has worked this way for ten years and has never needed one. Those reasons are understandable, but they do not change the fact that you are about to commit several million baht on the strength of a document with no detail in it.

The solution that is fair to both sides is to ask for a BOQ at trade-section level with the main material specifications stated, which does not expose the contractor’s internal cost structure. Failing that, commission the designer or a home-building company to produce a master BOQ and have the contractors quote on that table instead. A contractor who is confident in their own pricing rarely objects.

The OBILIS team prepares a BOQ for every owner before the contract is signed, and uses that same table to verify each stage payment right through to handover. Whoever you end up building with, insist on seeing this document before you agree a price, because once the contract is signed your leverage is largely gone.

To get a rough budget before you talk to anyone, try our house price calculator, or contact the OBILIS team to talk through your plot.

Related reading: Construction Payment Schedules in Thailand: A Safe Split

Frequently Asked Questions

How is a BOQ different from a quotation?

A quotation tells you the total price. A BOQ tells you which items that total is made of, in what quantities and using which materials. A serious quotation should always have a BOQ attached to it.

Who prepares the BOQ?

Normally the designer or the home-building company takes the quantities off the drawings, and the contractor fills in the rates. If you hire an independent contractor directly, the contractor usually prepares the BOQ from the drawings they are given. An owner can also pay an independent quantity surveyor to produce a master BOQ purely for comparing quotes.

Is it expensive to have a BOQ prepared?

Measured against the cost of the whole house, it is a small amount, and it is often already included in the design fee or in a home-building company’s service. The saving from correctly comparing quotes on a single line item is usually enough to cover the entire document.