Terms

Cost My Extension is run by Oliver Davidson, trading as Cost My Extension, 12 College Gardens, London SE21 7BE. You can reach us at [email protected]. We are not registered for VAT. These terms apply whenever you buy a report on costmyextension.co.uk.

A written report about the extension or loft conversion you describe, generated when you buy it from the answers you give, public records about the property and a set of current London build rates. It sets out a cost range with the lines behind it, a schedule of works, the likely planning route, the other approvals that may apply, a timeline, the risks and questions to put to anyone who quotes. It is a web page at a private link, which you can print or save as a PDF.

The free check on the home page, and the full free check we email on request, are a shorter screen of the same kind. They cost nothing, and everything in section 03 applies to them too.

This report is an informed estimate built from public data about your property and current London build costs. It is not a survey, a quote, a valuation or planning advice. Always get written quotes and, where noted, professional advice before committing to work.

The report is not a survey, a quotation, a valuation, structural or planning advice, or confirmation that any work is lawful. The planning section is a screen of the permitted development rules against your answers and the public registers; only the local planning authority can confirm whether work is lawful, through a lawful development certificate or a planning decision. Figures are ranges and are given in good faith; builders' prices, ground conditions and your own choices decide the final cost.

Use the report to plan, to set a budget and to question the people who quote. Before you commit money, sign a building contract, buy a property or borrow against the work, get written quotes and, where the report says so, professional advice.

The price is £12, with no VAT charged. The price you pay is the one shown on the button before you pay, less any promotion code you use. Promotion codes apply only as stated with them and cannot be exchanged for cash. Payment is by card through Stripe, which handles your card details; we never see them.

Our contract with you starts when your payment is confirmed. We then email you a receipt with the permanent link to your report.

The report is digital content, written straight after payment and usually ready in about a minute. Before you pay, you tick a box to ask us to deliver it at once and to acknowledge that, once delivery has begun, you lose the 14-day right to cancel that would otherwise apply under the Consumer Contracts (Information, Cancellation and Additional Charges) Regulations 2013. We record the time you ticked it and confirm it in your receipt email.

The report stays at its link for six years from purchase, then it is deleted, as the privacy page explains. Anyone with the link can open it, so share it only with people you want to read it. Print it or save it as a PDF if you want to keep a copy for longer.

If your report cannot be written within an hour of payment, we refund the full price automatically and email you to say so.

On top of your legal rights, we make this promise: Not useful? Reply to your report email within 14 days and we refund it, no questions asked. The refund goes back to the card you paid with, through Stripe, and banks usually take five to ten days to show it.

Within 30 days of purchase you can change your answers about the same property and have the report written again, up to 3 times, at no cost, from the link at the end of the report. A report for a different address is a new purchase. Once a report has been refunded it cannot be written again.

Under the Consumer Rights Act 2015, digital content must be of satisfactory quality, fit for its purpose and as described. If the report is not, write to us at [email protected]: you are entitled to have it put right or replaced, or, if that cannot be done, to some or all of your money back. Nothing in these terms takes away those rights. Citizens Advice (citizensadvice.org.uk) explains them in full.

The report relies on your answers being accurate. If an answer is wrong, the report will be too, and that is not a fault in the report; you can correct it with a free re-run under section 06. Public records can be out of date or incomplete, and every lookup can fail; where one does, the report says so and works from your answers alone. Address data from the Energy Performance Certificate register is used only to match your property and is never shown or stored.

We own the copyright in the report and the site. The report is for your own use, or for your client if you bought it as a professional acting for them. You may print it and share it with the people advising or quoting on your project. It may not be resold or republished.

If we break these terms or fail to use reasonable care and skill, we are responsible for loss you suffer that is a foreseeable result. We are not responsible for loss that is not foreseeable. Because the report is an estimate to plan with, and section 03 asks you to get quotes and advice before committing money, it is not foreseeable that you would rely on it alone for a decision such as signing a building contract, buying a property or borrowing money, and we are not responsible for loss that follows from doing so.

If you buy as a professional or for a business, the Consumer Rights Act does not apply to your purchase. We are not responsible to you for loss of profit, business or opportunity, or for any indirect loss, and our total responsibility for a report is limited to the price paid for it.

Nothing in these terms limits our responsibility for death or personal injury caused by our negligence, for fraud, or for anything else the law does not allow us to limit.

The report depends on outside services: the public registers, our payment, hosting and email providers, and the AI model that writes the wording. If one fails, we work around it where we can, as section 08 describes, and if we cannot deliver your report at all we refund it under section 06.

If something is wrong, write to [email protected] and say what happened. We aim to reply within five working days. How we handle your personal data is on the privacy page.

We may update these terms. The terms on this page when you buy apply to that purchase. They are governed by the law of England and Wales. If you live in Scotland or Northern Ireland, you can also bring proceedings in your own courts. Last updated 20 October 2026.