In the past few years, my partner and I have spent tens of thousands of pounds in home renovations – with more planned works over the next year. When organising the finances for this next project, I was alerted to the fact that some renovations can in fact invalidate your mortgage. Queue a flood of panic. Thankfully, all the works we’d carried out were deemed upgrades or maintenance. But it got me wondering, what projects could invalidate your mortgage? What else do home owners need to know about renovations before carrying them out? We talk to Andrew Boast, CEO of SAM Conveyancing, home buying and selling specialists, to understand the circumstances that could breach your mortgage – and even your insurance – terms.
“With mortgage lenders looking to loosen their lending criteria to allow a minimum of 6 times your annual income, they are investing a lot of money in your home. In fact in 2025, the average Loan-to-Value (LTV) for mortgages in England and Wales remains around 79% to 82% for first-time buyers and significantly lower, at approximately 65% to 70%, for home movers.
“With so much invested in your home, this is why the mortgage application process is so detailed with assessing your finances, but also assessing the property’s value in its current condition. The lender doesn’t want to lend 82% of the property’s purchase price, if, in its current condition, its true market value is lower. This is because they have to be satisfied that they can recoup their loan by selling your home, if you can’t or don’t pay them back.
“However what most borrowers don’t understand is their obligation towards their mortgage lender extends past getting their mortgage offer. In fact they are bound to put and keep the property in good repair. Failing to keep your property in good repair could mean you lose it.
“Within the Royal Bank of Scotland’s mortgage terms it states: “You will allow us and our representatives to have access to the Property at all reasonable times to carry out any survey or inspection which we may reasonably require”. If the lender finds the property isn’t being kept in good repair, then you must “carry out (at your expense) any material maintenance or repairs which you have failed to do and which may jeopardise the value of the Property as security for the Customer’s Obligations”. This means if the property’s value is falling lower than is adequate to protect the mortgage lender’s security, then you must pay to get the works completed.
“If you fail to make repairs to the property to ensure the value of the property doesn’t offer adequate security for the mortgage, then the lender could make an application for breach of the mortgage terms and make a demand for immediate repayment of their loan. If you can’t pay, then the mortgage lender is likely going to make an application to repossess the property. If you get repossessed you could lose your home, have to pay additional charges, and your credit score will be negatively impacted so you’re unable to get another mortgage immediately.”
Do building works breach the mortgage terms?
“The maintenance of the property is but one obligation you are required to adhere to as part of your mortgage terms and conditions. Another one is obtaining written permission for certain works. Whilst adding a single rear extension, removing a wall to open up the living space, and adding a bedroom will have a positive impact on the property’s price, to achieve this you may end up being in breach of your mortgage terms.
“A borrower is obligated to obtain written permission before “changing the use of the Property, altering, demolishing or extending it, or applying for permission to change its use or for structural alterations or additions, including the construction of additional buildings”. Here are some examples where you are likely to need to obtain written consent from your lender before undertaking the work:
- Removing a load bearing wall
- Installing double glazing
- Removing a chimney
- Extending the property
“The obligations to the lender and to the Building Control Laws are different, so just because you don’t need to get Building Control sign off, doesn’t mean you don’t need to inform your mortgage lender.”
What if the sledgehammer has already been swung?
“If you have already started structural alterations without prior written permission from your mortgage lender then you are in breach of your mortgage terms. It is both a common and serious issue. You should speak to your mortgage lender immediately.
“If the works fall under building regulations then the mortgage lender will want to know the works meet with current building regulations. To do this, you can:
- Get the works signed off by a competent builder who informs the council for you and registers the works as Building Control compliant; or
- Inform the council’s building control to attend the property and either sign off the works, or confirm what works need to be done for the sign off to take place.
“The best advice is to always use a builder who is a competent person and signs off the works at building control for you. They often cost more, but cause less of a headache.”
Is the property insured if you alter it?
“Standard Residential Building Insurance policies exclude any alteration works from its cover. John Lewis Building Insurance state: “These exclusions apply to all the Options of the policy…repair, alteration, renovation or restoration”. This means if you knock down a wall and the house collapses, your building insurance is void.
“This further extends to after the works have been completed. If you’ve had poor materials or workmanship, and there is damage caused, then you are not insured. Insurers state: “These exclusions apply to all the Options of the policy…any loss, damage, liability, cost or expense of any kind caused by or resulting from poor or faulty design, workmanship or materials”.
“You should speak to your insurer and ask what additional cover is available to protect you in the event the alterations causing damage to your property.”
Andrew, CEO, Executive Director, and Co-Founder of SAM Conveyancing, brings over 22 years of experience guiding thousands of clients through complex home purchases. A qualified accountant, he’s a recognised conveyancing expert who has advised The Telegraph on homebuying during the pandemic and successfully uncovered critical exclusions in the Government’s Help to Buy ISA scheme, leading to significant policy changes. Andrew is the author of several guides, including “How to Buy a House Without Killing Anyone,” and is a frequent commentator on BBC and other major news outlets, actively championing homeownership. He also mentors aspiring entrepreneurs at Royal Holloway University of London.
Evidence and sources
- The data provided is based on the following 2025/2026 reports:
- UK Finance (Q2 2025): Confirmed Wales LTV at 82.1% for first-time buyers.
- MoneySuperMarket (2025): Reported the national first-time buyer average LTV at 79%.
- Barclays Property Insights (Feb 2026): Highlighted that 44% of new buyers are now in the 85-90% LTV bracket.
- HouzeCheck/UK Finance (2025): Tracked the rise in English FTB LTV from 74.7% to 77.1%.
Featured image: Pressmaster, Canva
