How to quote for a job you cannot see yet

When a customer asks for a price on a job you cannot inspect yet, you need to quote using clear written assumptions and provisional sums so you do not absorb unexpected costs. Blind quoting is one of the quickest ways for a UK sole trader to lose money on materials and labour, but a solid structure keeps you safe. Here is how to handle unseen work properly from your first conversation to the final invoice.

Why blind quoting creates expensive problems for tradespeople

Quoting without a site visit is common when customers are in a rush or properties are tenanted, but it relies on guesswork. If you estimate a bathroom refit from photographs alone, you might miss rotten subfloors, outdated plumbing, or awkward pipe runs. When you start the work, those hidden surprises come out of your own pocket if your original price was fixed.

To protect yourself, you need to draw a hard line between what you can see and what you cannot. Never guarantee a fixed price for an entire project when half the details are hidden behind plaster or floorboards. Instead, break your paperwork down into clear line items so the client understands the limits of your initial figure.

Using digital quoting tools makes it easier to set these boundaries clearly before you start any physical work on site. When your exclusions and assumptions are printed in black and white, there is no argument later about what was included in the original price.

• Only give a fixed price for clearly visible elements.
• List every single assumption you are making about the property.
• State clearly what happens if you find hidden damage or non-compliant work.

How to use provisional sums for the unknown parts

A provisional sum is a placeholder amount in your quote for work or materials that cannot be priced accurately yet. For example, say you are wiring an old extension and you suspect the consumer unit needs upgrading, but the main board is locked behind fitted units. You insert a provisional sum for the board change while pricing the visible cable runs properly.

Make sure you explain provisional sums to the customer in plain English before they sign anything. Tell them that the figure is an educated placeholder, and that the final bill will go up or down once you strip back the finishes and see the true state of the installation. This manages expectations right from the start.

If you use dedicated scheduling apps to manage your diary, you can block out extra investigative time on the first day to finalise these figures before ordering materials. That way, you avoid costly second trips to the merchants.

• Use provisional sums only for genuine unknowns.
• Explain to the client that provisional sums are estimates only.
• Agree on a process for reviewing provisional sums once the work begins.

Writing clear assumptions so you never lose money

Assumptions are the ground rules of your quote. They state the exact conditions you expect to find when you arrive on the job. If those conditions turn out to be false, your price changes. For instance, a plumber might state that their quote assumes existing isolation valves work and that the floorboards are lifted and clear of debris.

Put your assumptions right at the top of your quote document where the customer has to read them. If you turn up to a plumbing job and find seized isolation valves that take an extra two hours to sort, your assumptions protect your right to charge for that extra time.

Keep a standard list of assumptions for your specific trade on your phone so you can drop them into every quote you send out. It takes two extra seconds but saves hours of awkward conversations later.

• Assume standard working hours and clear, unobstructed access to the work area.
• State that existing services comply with current regulations.
• Clarify who is responsible for waste removal and skip hire.

Converting your unseen quote into a signed job

Once you have built your quote with provisional sums and assumptions, you need the customer to accept the terms before you lift a finger. Send the quote via email so there is an automatic paper trail of what was agreed. Do not rely on verbal agreements over the phone when dealing with complex or unseen jobs.

Prompt the customer to review your assumptions and sign off on the provisional sums digitally. When clients can click to approve a quote online, it cuts down the friction and gets you booked into the diary much faster.

After the job is finished and you have accounted for any variations found during the work, streamlined invoicing lets you bill the exact final total without delays or manual calculations.

• Always send quotes in writing with a clear acceptance button or signature line.
• Get written approval for any changes before doing extra work.
• Keep your customer details organised so you can track variations easily.

Quick questions

Quoting for unseen work does not have to be a gamble if you use provisional sums and write down your assumptions clearly. Take five minutes on your next quote to spell out what is included and what is not. For a simple way to build professional quotes, manage your diary and keep track of your paperwork, try Maintenato free while it is in beta.