Aipedia: Interior designers

AI budgets and cost estimates: avoiding underestimates

Aipedia, by the Apex broking team · Last reviewed 2026-10-27

AI tools can produce a refurbishment budget in seconds, but the figures are often based on generic or out-of-date prices and can badly understate real costs. Clients rely on budgets to decide whether to proceed, so an underestimate can become a claim against the designer.

Part of: AI in Interior designers

In short

Interior designers may use AI to draft room-by-room budgets, cost plans and fee estimates. These tools rarely know local labour rates, current supplier prices, the condition of the property or the client's specification level. BIID Code clause 4(a) requires reasonable skill and care, 4(b) impartial advice, and 1(b)(i) taking on only work you are competent to do. Budgets presented as reliable invite reliance. Label AI figures as indicative, base budgets on real quotes, involve a cost consultant on larger jobs, and keep the client informed as prices change. PI may respond to negligent cost advice, subject to the wording.

How designers use AI for budgets

Clients usually want to know early what a scheme will cost. AI tools can turn a room list and a style description into a costed outline, split by furniture, finishes, joinery and labour. Designers may also use AI to draft fee proposals and to compare supplier prices. The output looks precise, often to the pound, which can give a misleading sense of certainty.

The duties that apply

The BIID Code of Conduct (1 April 2026) has no AI provision. The relevant clauses are:

4(a): reasonable skill and care to the normal standards of the profession;
4(b): impartial professional advice and judgement;
1(b)(i): take on only work you are qualified and competent to do, which matters if detailed cost planning is outside your expertise;
3(b)(iv) to (v): the written agreement must set out your fee and any expenses;
3(b)(xi): variations to scope or fees agreed in writing in advance.

See the BIID Code and AI guide.

What can go wrong

Illustrative scenario. A designer uses an AI tool to produce a budget for refurbishing a period townhouse. The tool assumes standard ceilings, sound plaster and mid-range joinery. The client takes out finance based on the figure. Once work starts, the house needs replastering, the joinery is bespoke and lead times push up costs. The final cost far exceeds the budget, the client cannot finish the project, and claims the designer's budget was negligent and that they would not have proceeded had they known.

Typical weaknesses in AI budgets are:

prices drawn from other regions, countries or years;
no allowance for the property's condition, access or listed status;
missing items such as delivery, installation, waste and contingency;
labour rates that do not reflect the local market.

Budgets and fee disputes

Budget problems often surface as fee disputes. A client who feels misled about costs may refuse to pay the designer's invoices, and the designer's attempt to recover fees then triggers a counterclaim alleging negligent advice. Clear terms on what the budget is, how it will be updated, and how changes to scope affect fees reduce the room for argument. The AI-drafted contracts guide covers the written agreement, and AI concept images explains how early images can anchor expectations too low.

How PI usually responds

Where a client claims they suffered loss by relying on a negligent budget, interior designers' PI may respond, subject to the policy terms. Insurers may look closely at whether cost advice was within the declared business activities, and the client's loss can be hard to prove where the work would have cost the same anyway. A pure fee recovery by the designer is not a PI matter. The cost of cover itself is explained in how much PI costs for interior designers. See also does PI cover AI and IP claims.

Indicative figures versus advice clients rely on

The legal risk depends less on the tool than on how the figure is presented. A range given in an early conversation, clearly described as a rough guide, is unlikely to be treated as professional cost advice. A detailed, itemised budget issued on letterhead, used by the client to arrange finance or agree a contract, looks much more like advice the client was entitled to rely on. AI tools make the second kind easy to produce without the work that should sit behind it. Decide before issuing anything which kind of figure you are giving, and say so in the document itself.

Practical controls

Label AI budgets "indicative only" and explain their basis in writing.
Replace AI figures with real supplier and contractor quotes before the client commits.
Include contingency and list what is excluded.
Recommend a cost consultant for larger or complex projects.
Update the client in writing when costs change, and record approvals.
Keep the sources behind each figure.

How Apex helps: Apex arranges PI for interior designers. A broker can check whether cost advice is within your declared activities and how your policy treats claims about AI-assisted budgets. See PI insurance for interior designers.

Sources

Frequently asked

Can I give clients an AI-generated budget?

You can share it as an indicative figure if you say clearly what it is based on and that it is not a quote. Before a client commits money, replace AI figures with real prices and include contingency.

Am I liable if the project costs more than my budget?

Not automatically. Costs rise for many reasons. Liability usually depends on whether your budget was prepared with reasonable skill and care, what you told the client, and whether they relied on it and suffered loss.

Does PI cover a claim over a budget overrun?

It may, if the client alleges negligent cost advice and that activity is covered by your policy, subject to its terms. Notify your insurer early if a client blames your budget for an overrun.

Check your PI covers how you use AI

Tell us about your firm and the work you do. A broker will review how your current PI treats AI-assisted work, or arrange new cover. No fee for a quote. Or call 0117 325 0027.

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Apex Insurance Brokers Limited is authorised and regulated by the Financial Conduct Authority. Registered in England and Wales, company number 07014570. This page is general information about how AI is used in the profession and how insurance may respond. It is not legal, regulatory or insurance advice on your circumstances, and it does not guarantee that cover will be available or on what terms.