Why Two Builders Quote Very Different Prices From the Same Drawings
You send the same set of drawings to three builders. One comes back at a number you expected, one comes back well above it, and one comes back so far below the others that it looks like a mistake. Same drawings, same house, same scope — supposedly.
The usual conclusion is that somebody is overcharging. Occasionally that is true. Far more often the three quotations are not describing the same job at all, and the differences are hiding in places the bottom line does not show you.
Here is what actually varies, in roughly the order it costs owners money.
1. What has been left out
The single biggest driver of a low number is usually not a lower rate. It is a shorter list.
The items most often absent from a cheap quotation are the ones that are awkward to price and invisible on a drawing: hoarding and site protection, disposal of demolition material, scaffolding, temporary power and water during construction, protection of the neighbours' property, cranage or lifting, making good the road verge and drain crossing, and the professional fees that sit alongside the works.
None of those disappear because they were not quoted. They arrive later as variations, at a moment when you have no leverage because the works have started and your builder is on site.
What to do: ask every builder for their exclusions list as a separate document. Not "is everything included" — the answer to that is always yes. Ask for the list. Then put the three lists side by side. That comparison alone usually explains most of the spread.
2. Provisional and prime cost sums
A provisional sum is a placeholder for work that has not been fully decided, and a prime cost sum is an allowance for a material you have not chosen yet. Both are honest devices. Both make bottom lines uncomparable.
If one builder has allowed a generous sum for sanitary ware and another has allowed a thin one, the difference is not a price difference. It is a guess about what you will eventually buy, and it will be adjusted to the real cost either way.
What to do: strip the provisional and prime cost sums out of all three quotations and compare what is left. That is the part where the builders are actually competing.
3. The same words meaning different work
"Waterproofing to wet areas" can be a full membrane system laid, flood-tested and warranted, or it can be a cement-based coating brushed on. "Piling" can mean several different systems with very different costs. "Reinstate existing finishes" can mean matching what is there or covering it.
Two builders reading the same line in a specification and pricing it honestly can land far apart, and both are right in their own terms.
What to do: pick the four or five lines that carry the most money and ask each builder to describe, in a sentence, what they have actually allowed for. The differences appear immediately.
4. One of them has been to the site
Drawings do not tell you that the access road is narrow, that a lorry cannot turn at the end of it, that the neighbour's wall is right on the boundary, that the existing structure is in worse condition than the survey suggests, or that everything has to be carried by hand from thirty metres away.
A builder who has walked the site prices what they saw. A builder who quoted from a PDF prices what they hope. The second number is lower, and it is lower because it is less informed.
What to do: weight heavily towards anybody who visited before quoting, and ask the ones who did what they noticed. It is the fastest way to find out who has actually thought about your job.
5. Preliminaries
Preliminaries are the cost of running the site rather than the cost of building anything: supervision, site office and facilities, safety provisions, insurances, utilities, and the time the site is open. They are a real cost on every project, they scale with duration, and they are the easiest thing to under-allow in order to arrive at an attractive total.
A builder pricing thirty weeks of proper supervision will look expensive next to one pricing a foreman who visits. You are not comparing rates there. You are comparing how much attention your house is going to get.
6. Programme
Speed costs money and so does slowness. A shorter programme means more resource on site at once. A longer programme means more weeks of preliminaries. If two quotations assume different durations they cannot produce the same number, and the duration is often stated nowhere.
What to do: ask for the programme in weeks alongside the price. Then judge the pair together.
7. How the unknowns were treated
Every A&A and every reconstruction has unknowns — what is behind the wall, what the existing foundation actually is, what the ground does at depth. A builder can carry a contingency for those, or leave them out and issue variations when they appear.
The first approach produces a higher quotation and fewer surprises. The second produces a lower quotation and a running argument. Neither is dishonest, but only one of them tells you at the start roughly what the house is going to cost.
8. Who is actually doing the work
Some builders carry their own crews and their own trades. Some sublet everything and coordinate. Some sublet everything and do not coordinate very much.
That structure shows up in the price and in the experience. Work kept in-house is easier to control and harder to discount; work fully sublet is cheaper to buy and depends entirely on the quality of the supervision above it — which brings you back to the preliminaries line you were tempted to trim.
9. Payment terms
A builder asking for a large sum up front is being paid to carry less risk, and that ought to be reflected somewhere. A builder billing against verified progress carries more, and prices it. The headline figure is not the whole commercial picture; the cashflow shape sits underneath it.
How to compare three quotations properly
- Ask all three for a priced breakdown in the same order, not a lump sum.
- Ask all three for a written exclusions list.
- Remove the provisional and prime cost sums from each and compare the remainder.
- Ask each to describe the four biggest line items in a sentence.
- Ask for the programme in weeks, and look at the price and the duration together.
- Ask the lowest bidder what they assumed about site access, disposal and existing conditions.
- Ask the highest bidder what is in their price that is not in a cheaper one. They will usually tell you plainly, and it is the most useful answer you will get all week.
The one that is far below the others
Treat a quotation well below the field as information rather than as an opportunity. It usually means one of three things: a different scope, an assumption about site conditions that is not going to survive contact with the site, or a deliberate low entry that will be recovered through variations.
It occasionally means a builder with genuine spare capacity who wants the job. That does happen. You find out which by asking questions six and seven above, and by how comfortable they are answering them.
Why we do not publish a price list
Everything above is also why there is no rate card on this site. A landed A&A price depends on access, on the condition of what is already standing, on how much of the existing structure survives, on the ground, and on what the approvals require — none of which a table can carry honestly. We would rather look at your drawings and your site and give you a number we can stand behind.
Wong Lye Pte Ltd holds a BCA General Builder Class 2 (GB2) licence and works on landed, industrial and warehouse construction across Singapore.
Related reading: why there is no price list for landed building works, the hidden costs first-time landed builders meet, and whether the architect and QP are inside the builder's quotation. If you are comparing on cashflow as well as price, progressive milestone billing explains the shape.
Message us on WhatsApp about comparing quotations, or read about the A&A work we take on.