Buying a house with an extension or loft conversion that lacks a completion certificate is a common situation. It is not automatically a reason to walk away from the purchase, but it requires careful handling. You need to make a firm decision with your conveyancer and arrange a house survey that pays close attention to the altered parts of the building.
Building Regulations set the standards that building work has to meet. When building work finishes, the local authority or an approved inspector issues a final or completion certificate to confirm the work meets these regulations. A missing certificate means there is no formal proof that the extension was built to the correct standards.
When someone sells a property, they are expected to provide specific paperwork to the buyer. The government guidance on preparing to sell a home states that sellers should gather FENSA or CERTASS certificates for windows, planning permission and building regulation certificates, alongside any guarantees, warranties and surveys. Where unauthorised work is not put right, no completion certificate is issued, and the Planning Portal says this is likely to come to light through a local land search enquiry.
What the council can do about unauthorised work
Local authorities have legal powers to deal with building work that does not meet the regulations. The Planning Portal outlines the specific actions a local authority can take against non-compliant building work.
The council enforces these rules through notices and prosecutions, which follow strict time limits. Your conveyancer or the local council will confirm exactly how these rules apply to a specific house.
- Local authorities may issue a compliance notice within 12 months of a contravention taking place.
- A section 36 notice can be issued up to 10 years after the completion of the building work.
- There are no time limits on bringing a prosecution of a contravention under Section 35 of the Building Act 1984.
- Appeals against section 35 or 36 notices must be made within 21 days.
What a surveyor can and cannot tell you
A surveyor inspects the physical condition of the property, but they cannot confirm Building Regulations compliance. The official description of the RICS Level 2 survey states that the visual inspection does not investigate plumbing, heating or drainage installations or whether they meet current regulations. It also confirms that the surveyor cannot assess the safety of electrical, gas or other energy sources.
Survey reports use condition ratings to highlight issues. A condition rating R means there are documents the surveyor may suggest you request before you sign contracts. The surveyor does not act as a legal adviser and does not comment on any legal documents.
While a survey cannot prove legal compliance, it is vital for checking the physical state of the unauthorised work. The surveyor will look closely at the altered parts to judge the building's overall condition and identify any repairs that may be needed. Because a standard inspection cannot test services, you should also arrange a separate gas and electrical test, carried out by suitably registered professionals, to check the safety of the installations.
Choosing the right survey level for an altered house
House surveys are sold at a fixed fee quoted up front, and the price is driven by the survey level, property value, size, age, complexity and location. It is vital to match the survey level to the age, type and condition of the property. A mortgage valuation is not a survey, as it is just a limited check for the lender's benefit.
A Level 1 survey describes the general condition, flags obvious risks and urgent defects, and suits conventional, newer homes in good condition. A Level 2 survey suits conventional homes in reasonable condition and adds specific advice on repairs and maintenance. This is a visual, non-intrusive inspection that comes as a survey only or a survey and valuation.
Where the building work is large, such as a major extension or a complex loft conversion, you should consider a Level 3 survey. This is the most detailed inspection and suits older, larger, altered, unusual or run-down homes. You can read more about what a Level 3 building survey covers to help you decide.
The table below shows the typical cost and duration of different survey levels for a home purchase.
|
Survey level |
Typical cost |
Inspection time |
|---|---|---|
|
Level 1 survey |
£300 to £450 |
1 to 2 hours |
|
Level 2 survey |
£400 to £950 |
2 to 4 hours |
|
Level 3 survey |
£600 to £1,500 or more |
4 to 8 hours |
These figures are typical 2026 prices, and local quotes will differ based on the specific property. Reports usually follow within about 3 to 10 working days.
Your options as a buyer
When your conveyancer discovers that a completion certificate is missing, you have several ways to proceed. You should discuss these with your conveyancer to understand the risks and timelines involved. Always ask for written quotes for any legal or insurance costs.
The table below shows the three standard routes to handle missing building regulations paperwork.
|
Option |
What it involves |
Main restriction |
|---|---|---|
|
Copy of certificate |
Asking the issuing body for a duplicate |
An administration fee may apply |
|
Indemnity insurance |
A policy arranged by your conveyancer |
Generally not available until 12 months after the work, and becomes invalid if anyone approaches the council |
|
Regularisation |
Asking the council to inspect past work |
Usually needs some opening up of the structure |
These are the basic paths available to buyers. Your conveyancer can explain which route suits your purchase.
Getting a copy of an existing certificate
Sometimes the building work was properly inspected and signed off, but the seller has simply lost the paperwork. You or the seller can ask the local authority or the approved inspector for a copy of an existing certificate.
An administration fee may apply for providing a duplicate document. If no certificate can be found, you will need to look at the other options.
Indemnity insurance and its limits
If the work was never signed off, your conveyancer can arrange an indemnity insurance policy. It does not mean the work has been checked, so it does not tell you the work is safe.
Indemnity insurance is generally not available until 12 months after the work was completed. Lenders can lend without a completion certificate, but they typically require indemnity insurance. This depends on the specific lender and their current policies.
There is a critical restriction with these policies. Indemnity insurance policies become invalid if anyone makes an approach to the local council. If you have no record of inspections, you must not contact the council to ask about the property. Always speak to your conveyancer before you speak to the local authority.
Regularisation certificates
If there is past unauthorised work, you may contact the local authority to discuss how you might be able to obtain a Regularisation Certificate. Speak to your conveyancer first, because an approach to the council can make an indemnity policy invalid.
Applying for regularisation usually needs some opening up of the structure. Do not open up any work yourself. Any opening up should be arranged with the council and the seller through your conveyancer.
Where the work is not put right, no completion or final certificate will be issued. The unresolved issue is then likely to come to light through a local land search enquiry whenever the property is sold in the future.
Common mistakes when buying an altered house
Buyers often make errors when dealing with extensions and loft conversions. One of the biggest mistakes is relying entirely on the mortgage valuation, assuming it proves the house is flawless. A mortgage valuation is not a survey and will not give you a detailed breakdown of structural defects.
Another frequent error is choosing the cheapest survey level for an old or heavily altered house. A Level 1 report will not provide the depth of advice needed for a property with complex unauthorised work. Buyers also make the mistake of not reading the terms of engagement, leaving them surprised when the surveyor does not lift carpets, move heavy furniture or test the heating system.
It is also a mistake to ignore recommendations for further investigation. If your surveyor suggests checking the electrics, you should read about the further investigations your surveyor recommends and book the relevant specialists. Finally, trying to renegotiate the purchase price without getting written repair quotes rarely works, as the seller has no proof of the actual costs.
Checking your surveyor is regulated and qualified
You need a competent professional to inspect an altered building. You should look for the letters AssocRICS, MRICS or FRICS after a surveyor's name, which shows they are a member of the Royal Institution of Chartered Surveyors. You should also look for the words RICS Regulated for the surveying firm itself.
You can confirm both the individual and the firm on the RICS Find a Surveyor service. RICS regulated firms must have a formal complaints handling procedure, give consumers free access to an independent alternative dispute resolution provider, and hold professional indemnity insurance. The RPSA is another recognised body for residential surveyors with its own survey products.
Under the Consumer Rights Act 2015, a surveying service must be carried out with reasonable care and skill. If you arrange your survey online or by phone, the contract normally carries a 14-day cooling-off period. If you ask for the inspection to start inside this cooling-off period, you must pay for what has been done if you subsequently cancel.
What good advice looks like
Good surveying advice starts before you even book the inspection. A reputable surveyor will help you match the survey level to the age, type and condition of the property. You should get two or three like-for-like quotes that clearly state the survey level, whether a valuation is included, and the expected turnaround time for the report.
When comparing quotes, ask the surveying firms about their experience with that specific property type and the local area. You should also ask whether the surveyor will talk the report through by phone once you receive it, as this conversation is highly valuable for understanding technical defects.
You should book the survey once your offer is accepted and well before you exchange contracts. Once you have the report, use the findings to get written repair quotes from local tradespeople. You can then decide whether to proceed with the purchase, renegotiate the price, or walk away entirely, keeping your conveyancer involved at every step.
Common questions
Will a missing certificate stop my mortgage application?
Lenders can lend without a completion certificate, but they typically require indemnity insurance to cover the risk. Whether they approve the mortgage ultimately depends on the specific lender and their individual lending criteria.
Can a surveyor confirm the extension is legally compliant?
No. A surveyor checks the physical condition of the property to find defects and risks. The RICS Level 2 inspection does not investigate whether plumbing, heating or drainage installations meet current regulations, and the surveyor does not act as a legal adviser.
Should I contact the local council to check the property history?
You must not contact the council without speaking to your conveyancer first. Indemnity insurance policies become invalid if anyone makes an approach to the local council regarding the unauthorised work.
Can I check the structural safety of the work myself?
Do not carry out your own structural checks, enter lofts, lift drain covers or disturb materials. Leave that to professionals, and ask your surveyor and conveyancer what further checks are needed.
Next steps for your purchase
Buying an altered property requires a logical approach to ensure you do not take on hidden liabilities. Follow these steps to protect your purchase.
- Instruct your conveyancer to check the local land search enquiry results for any missing completion certificates.
- Ask the seller if they have a copy of the final certificate, or if they are willing to pay the administration fee for a duplicate.
- Book a survey that matches the age and condition of the property, opting for a Level 3 survey if the extension is large.
- Read the terms of engagement carefully so you understand exactly what the visual inspection covers.
- Arrange a separate gas and electrical test to check the safety of the installations.
- Discuss indemnity insurance and regularisation with your conveyancer before you speak to the local authority.
- Use the survey findings to get written repair quotes before you attempt to renegotiate the purchase price.
Finding a qualified professional early gives you time to understand the true condition of the extension and make an informed choice. You can compare local practices and find a surveyor near you to inspect the property thoroughly before you commit to the purchase.
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