Most builders don't lose money because they're bad at their trade. They lose money because of avoidable mistakes in how they price the job. Here are the seven most common quoting errors — and how to fix them.
1. Using Old Material Prices
You quote a job in January using the prices you paid in November. Timber has moved up 8%. Insulation board is on allocation. By the time you start in March, your material costs are higher than what you quoted — and you have no mechanism to recover that.
Fix: Pull live prices at the point of quoting, not last month's prices. Use a tool with up-to-date UK trade price libraries. Add a clause allowing material cost revision if there's more than a 30-day gap between quote and start.
2. Underestimating Labour
The classic mistake: you estimate 10 days for a job and it takes 14. At £300/day per operative, that's £1,200 you didn't price for. Do this on five jobs a year and you've given away £6,000.
Fix: Track your actual labour time on every job — not just total days, but by trade/phase. After 6 months you'll have your own real productivity rates based on your team's actual performance, not industry averages.
3. Not Including Your Overheads
Your van costs money. Your tools need replacing. Your insurance, phone, accounting software, fuel — these are real costs of running a building business. But most builders don't systematically include them in their quotes.
At a minimum, overheads represent 8–15% of your turnover. If you're not building this into your pricing, you're subsidising your clients' jobs out of your own pocket.
Fix: Calculate your annual overhead costs (van, insurance, tools, software, fuel, professional fees). Divide by your annual working days. Add a daily overhead recovery figure to every job you price.
4. Forgetting Provisional Sums
You start groundworks and find the soil is heavy clay — three times more expensive to break up and remove than the sandy topsoil you assumed. You hit a drain that wasn't on any survey. You open a wall and find timber frame where you expected block.
These aren't uncommon. They happen on virtually every job. If your quote has no provisional sum for unknowns, you bear the entire cost.
Fix: Include a clearly stated provisional sum in every quote — typically £1,500–£3,000 on a mid-size job. Make sure your contract allows you to invoice against it when the unknowns materialise.
5. Not Charging for Variations
The client asks for small changes throughout the job. You do them. You don't charge for them because each one feels too small to raise an invoice for. By the end of the job, you've done 20+ unpaid "small" tasks that add up to days of uncharged labour.
Fix: Have a written variation procedure in your contract. Issue a variation notice for every change — even minor ones. If you do this consistently from the start, clients expect it and accept it. If you start charging partway through a job, it creates friction.
6. Quoting Too Quickly Without a Site Visit
A client sends you a WhatsApp message with photos and asks for a quote. You estimate £35,000. You arrive on site and immediately see three problems you couldn't see in the photos — a chimney breast that complicates the roof structure, a conservatory that needs to come down first, and a shared drain that will require a party wall agreement.
Fix: Never quote a job from photos or a brief description alone. If a full site visit isn't possible before the quote, build in a large contingency and clearly state what you haven't been able to assess. Better to lose a quote than to win a job you lose money on.
7. Quoting Net Without Thinking About VAT
If you're VAT registered, your client pays 20% VAT on top of your quoted price. That's fine — but problems arise when you're not clear in your quote about whether prices include or exclude VAT.
A client who agreed to a £40,000 extension quote and then receives an invoice for £48,000 will feel misled — even if you were technically correct. That's a relationship-damaging moment that can lead to disputes, delayed payment, and bad reviews.
Fix: Every quote should clearly state "All prices exclude VAT" or "All prices include VAT at 20% where applicable." For residential work, most construction is VAT-exempt at 0% (new builds) or 5% (conversions of residential property). Know your VAT position on each job type and state it clearly.
The Common Thread
Most of these mistakes come down to the same thing: quoting quickly without a systematic process. When you have a professional quoting system that forces you to price every element, track every variation, and see your live margin — these mistakes either disappear or surface early enough to fix.
QuoteBuild gives small UK builders that system without the weight of enterprise software. Start your free trial and see how it changes the way you quote.
If these mistakes show up in your own quotes, see how the process works or compare plans.
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