Choosing a contractor, and what to ask them

A client sends the same job to three builders and gets back £38,000, £46,000 and £61,000. The natural conclusion is that one is cheap, one is fair and one is trying it on. The more likely explanation is that they have priced three different jobs, because the information they were given left room to.

Everything below follows from that. Most of the work of choosing a contractor happens before any of them see the job.

Give them all the same document

A builder pricing from a conversation and a rough sketch has to guess. Guesses get priced conservatively, or optimistically, and either way you cannot compare them.

What they need, at minimum: drawings of what exists and what is proposed, a written schedule of works describing each element in order, a specification naming the actual products where you have chosen them, and a clear statement of what is excluded. If the tile is not chosen, give a supply cost allowance per square metre and say so, so that every quotation carries the same allowance.

Say who is providing what. Appliances, sanitaryware, light fittings, ironmongery, and whether the builder is supplying and fitting or fitting only. This one distinction accounts for an enormous amount of the variation between quotations.

State the programme constraints. If the house has to be habitable throughout, or the shop has to reopen on a fixed date, that is a cost and a builder needs to price it. On the cafe refit on a market square the fixed reopening date was in the tender document on page one, because it was the most expensive requirement in the job.

The questions worth asking

Once you have quotations, meet each of them. What you are trying to learn is not whether they are nice, it is how they run a job.

Ask what work they have on at the moment and what they have booked after yours. A builder with nothing on in six weeks and a builder with two jobs running are different risks, and neither answer is automatically bad, but the answer tells you whether your programme is realistic.

Ask who will actually be on site. Many builders subcontract most trades, which is normal and fine. What matters is which of them are people they have worked with for years and which are being found for this job.

Ask how they handle a variation. The answer you want is that any change is priced and agreed in writing before it is carried out. The answer you do not want is that they will sort it out at the end.

Ask what they think is going to be the difficult part. A builder who has looked at the job properly will have an opinion, usually about access, drainage or something structural, and it will very often be the same thing your designer is worried about. A builder who says it is all straightforward has either not looked or is telling you what you want to hear.

Ask for two references, and specifically ask for one job that went wrong. Every builder has one. What you learn from that reference is how they behave when something is difficult, which is the only thing you actually need to know.

What to check on paper

Public liability insurance, and the certificate, not a claim that it exists. £2 million is a normal minimum for domestic work. If they employ anyone, employer's liability as well.

Gas work must be by a Gas Safe registered engineer and electrical work should be certified under one of the competent person schemes, or notified to building control separately. Ask for the registration number and check it against the register rather than looking at a logo on a van.

If you are paying anything up front, understand what it is for. A deposit against materials ordered specifically for your job is reasonable. A deposit of 30 per cent of the contract value before anyone starts is not, and it is the most common route to losing money.

Agree a payment schedule tied to stages of completion rather than to dates, and keep a retention of around 2.5 to 5 per cent for six months after completion. A retention is not distrust, it is the mechanism that gets the snagging list done.

Use a written contract

For work of any size, a short standard form contract is worth the hour it takes. It sets out the price, the programme, the payment stages, how variations are handled and what happens if something goes wrong. Builders who work properly are generally relieved to have one, because it protects them from a client changing their mind as much as it protects you.

An email exchange confirming scope, price, start date and payment stages is better than nothing and is not a contract. It is the minimum.

The cheapest quotation

Sometimes the lowest number is the right one, and it is usually the one from the builder who has priced tightly because they know the job well and want it. More often it is low because something is missing, and the missing item reappears later as a variation at a price nobody negotiated.

The way to tell the difference is to go through the low quotation line by line against the schedule of works and find the items that are not in it. If everything is there, it is a good price. If four things are missing, you have not been given a discount, you have been given an incomplete list.

This is the part of the service most people are surprised we spend time on. Running a tender properly takes a couple of days, and on a £45,000 job it routinely saves more than it costs. It is also the point at which the decisions in how to budget a renovation without lying to yourself either hold up or fall apart, and the point at which the practicalities in living in the house while the work happens stop being theoretical.