Buying an Old House in the UK: What to Check Before You Offer
- Real Life Architecture
- Feb 15, 2025
- 12 min read
Updated: 2 days ago
Níall Hedderman · ARB-registered architect · RIBA Chartered Member
I've run my own architecture practice in Edinburgh since 2009, specialising in altering, extending and renovating homes. Since 2022 I've given over 340 online consultations to homeowners and buyers across the UK.
Over a million homes are sold in the UK every year, but fewer than 200,000 of those are new build. That leaves around 800,000 older homes changing hands annually.
If a new build has problems you can usually get the builder to put them right, at least in theory. And not many people buy a new build intending to alter or extend it immediately. Older houses are different, and they come with their own set of problems.
There is a gap in the market here. There are plenty of solicitors, surveyors and mortgage advisors to answer questions about title deeds, subsidence or interest rates. But who do you speak to if the property you are considering needs its layout changed or an extension added? How much will that cost, how long will it take, will it get planning permission, does it comply with the building regulations, and is it even the best use of the money?
I get all of those questions. Back in 2022 I started offering online consultations to homeowners across the UK, and the most popular one by some distance is for people who want advice before they buy.
A surveyor and an architect look at different things
This is the distinction that matters most, and most buyers don't know it.
A surveyor tells you what is wrong with the house. An architect tells you what you can do with it.
Those are complementary skills, not interchangeable ones. A survey reveals the property's defects and its current condition. An architect's input reveals its potential — what is possible, what is not, where to compromise and where to spend.
You want both. I always advise buyers to get a RICS survey, and nothing on this page replaces one. What follows is the other half of the picture.
“Niall gave me pre-purchase advice before making an offer on a property and it was excellent. Clear, detailed, and tailored to the specific house, not generic fluff. Saved me time, money, and a few bad decisions.”
— Ross Targett, Google review
What I need from you before a consultation
People message me through this website asking whether the property they have in mind is suitable for a consultation. Some worry they don't have enough information, others send me several paragraphs about their wants and needs. There is a happy medium. To advise you on a property I need four things.
The full postal address. I use this to look at the property on Street View and to pull its history from the local planning portal.
Photos or floor plans. The estate agent's online listing is ideal. It usually shows both the layout and the condition.
A description of what you want done. New heating, replacing windows, converting the attic, taking down internal walls, adding an extension. I want the full wish list, not the edited one.
A budget. Most people have no idea what building work costs, and that's fine. I need a figure you don't want to go beyond — your savings, or the gap between the mortgage and the sale price. Tell me your ceiling and I'll tell you whether it matches the wish list.
I don't advise on properties outside the UK. That comes down to my insurance and to my own experience — I've spent my career in the UK and I don't know enough about construction elsewhere to give anyone professional advice on it.
Four checks you can do yourself, for free
Before you pay anyone anything, there is a surprising amount you can find out from your kitchen table.
The planning history — of the house and its neighbours. Your local authority's planning portal is public. Search the address and read what has been applied for, what was approved, and what was refused. Then do the same for the houses either side. Neighbouring applications tell you what the planners are likely to accept on that street, and whether anyone nearby makes a habit of objecting. A neighbour with a history of objecting is a live constraint on what you'll get permission for, and almost nobody checks.
Street View, backwards through time. Google Street View has a timeline that lets you see the same house in earlier years. Mature trees felled near the building can point to root damage to foundations, drains or boundary walls. New retaining walls or dug-up gardens often mean drainage or subsidence has been dealt with. Extensions or dormers that appear between captures should be cross-checked against the planning history — a building extended without permission is a problem you would inherit. Re-rendering, re-roofing or scaffolding appearing more than once suggests defects that weren't fixed properly the first time. Skips outside the house in several captures tell you previous owners have had to spend.
Drainage records. What is buried under the garden constrains where an extension can go. Public sewers running through the plot are a common and expensive surprise, and repeated drainage work is a subsidence tell. Ask the water authority for a drainage map before you assume the back garden is available.
Listed status and conservation area. Both are public records and both severely restrict what you can alter. Neither is a reason not to buy, but each has to be a deliberate choice rather than something you discover after exchange.
Start with the roof
If there is one thing I would tell everyone to look at before buying an older property, it is the roof.
The older the house, the higher the chance the roof needs work. You might think there are any number of things needing attention — the electrics, the heating, the windows. But picture spending your entire budget renovating the inside and then discovering the roof leaks. If it has been leaking a long time the timbers may be saturated and the rafters affected by wet rot. Repairing a roof is never easy or cheap, and watching water run down a freshly decorated wall is worse.
It can be hard to tell from photographs, but there are usually signs.
Take this row of semi-detached houses. They are around a hundred years old, and some of the roofs are in better shape than others.
Slates out of place. Over time these let in wind-driven rain.
Patchy repairs. If corners were cut here, what else has been neglected?
Moss on the slates, which can mean they are starting to delaminate and may need replacing.
The occasional replaced ridge tile — another sign maintenance has been piecemeal.
Some bay windows have lead flashing, others have mortar, and some of the lead looks newer than the valleys on the main roof. That suggests the bay roofs have leaked in the past. Whether the timbers underneath are still sound, nobody knows from a photograph.
Vegetation growing in the chimneys and washed-out pointing, both reliable signs of damp. One chimney on that street isn't the same design as the others and looks to have been partially taken down, which is worth asking about.
Tired barge boards. Not structural, but combined with moss and damp chimneys they tell you the house has not been looked after for years.
Inspecting a roof from the outside only tells you so much. A roof that has leaked over a long period causes damp and rot inside, hidden under floors and inside walls. The only way to find that is to look.
When you need an invasive survey
I regularly advise buyers to have an invasive survey done. That means drilling holes in walls or ceilings, lifting floorboards, and generally damaging the fabric of the house to find what is hidden.
Obviously you can't walk into someone's home and start taking it apart. But in my experience, if you offer the current owner a modest financial inducement, they will often agree. Have your solicitor offer a sum — say £500 or £1,000 — to cover repairing and redecorating the areas you want opened up. If the survey finds something serious and you walk away, the owner has the money to put it right.
One thing worth knowing. If you are buying with a mortgage the lender will insist on a survey, but these are often basic visual inspections, and there is a real question about who the surveyor owes their duty of care to. Is it you, or the bank? If you are planning an invasive survey, appoint an independent surveyor whom you pay directly and who is not reporting to the lender. You can find qualified surveyors through RICS.
“He flagged potential issues with the boundary and drainage we should be aware of before going too far into the design phase, therefore spending considerable sums. It was also useful to get an impartial view on what is realistically possible.”
— Gav Main, Google review
Three properties I've been asked about
A survey tells you the condition. It doesn't tell you whether the thing you want to do is possible. These are three real properties people asked me about before they made an offer.
A 1970s split-level house on a hillside
The client wanted to know, before buying, whether the house could be made larger. They needed an extra room as a study or bedroom, and better access to the rear garden. Their budget was up to £200,000.
The neighbour had already extended above their front porch and garage. When I pulled the planning drawings from the local portal, the headroom inside that new space looked very tight — probably under two metres. My client could likely get permission to do the same, but they would want a flat roof to maximise headroom rather than the shallow pitched tile roof next door.
I also told them to talk to the neighbours and ask about the foundations. Building another storey on top of an existing structure, particularly a garage, depends on the existing foundations being strong enough, and they often aren't. If underpinning is needed, expect construction costs well above average.
Because the house sits on a steep slope it has an upside-down layout, with kitchen and living space upstairs and bedrooms below. That works, because you enter from the high side of the slope into the living space and get the view.
What you can't do is reach the garden without going through the bedrooms.
The client wanted a balcony or deck at the rear with steps down to the garden. That is feasible, but planners could refuse it if it overlooks the neighbour's windows, so the design would have to take their privacy into account.
All of it was affordable within the budget. But if they also wanted to rewire the house or install modern central heating, that would affect the 1970s wood panelling, and replacing that costs money too.
A semi where the extension broke the rules
This two-storey semi looks ordinary enough. The client had £100,000 to make the changes they needed. That sounds like a lot and it doesn't go far.
They wanted to take out the bay window and fill in the area at the rear to form a large kitchen, living and dining space, incorporating the existing extension. That would have been just about affordable, provided the existing building didn't need major changes. It did.
The existing extension has more than 25% glazing — that is, the area of glass is greater than a quarter of the floor area. With the entire roof glazed and windows that size, it is over 100%. The space is open to the house rather than separated by a door, and it has kitchen units in it. None of that complies with the current building regulations.
I couldn't establish when it was built, and I advised the client to have their solicitor ask whether building regulations approval was ever granted. My guess is that it wasn't, at least not in this layout, but it is always worth asking.
If they went ahead, they would have to make changes. They could keep the glazing, move the kitchen elsewhere and put a door between the extension and the house. If they wanted to keep the kitchen where it is and leave the space open, the glazed roof has to go, replaced with a new insulated flat roof. That would be a marginal extra cost if they were building an extension at the same time.
The client knew their budget was tight and wanted my view before committing. They had no idea the kitchen was a problem until they got in touch.
A flat where a bedroom had become a bathroom
This client already suspected there was a building regulations issue, and asked before making an offer.
Previous owners had converted the second bedroom into a larger second bathroom. I would guess the ground floor flat was home to someone with limited mobility. My client needed it turned back into a bedroom, and was worried that other changes made to the building had made that impossible.
From the existing and proposed drawings on the local planning portal, the flat had been extended and the area outside the window enclosed.
That window used to look onto the rear garden. Now it opens into a tiny courtyard. If turning the bathroom back into a bedroom required an escape window, this wouldn't work — an escape window has to meet a minimum size and open into a space deeper than the building is tall. That courtyard is far too small.
So was an escape window required? The building has been divided into flats and the topmost floor looks to be more than 4.5 metres above external ground level, which sets the fire safety criteria for the whole building.
The English building regulations offer several options in this situation. The simplest for my client was to keep the existing corridor to no more than nine metres, measured from the kitchen door to the flat's entrance door, with fire-resistant walls and self-closing fire-resistant doors.
I couldn't confirm it from the drawings alone, but it appeared to work, and I advised them to have the measurements checked by a surveyor. The good news is that a bedroom in that situation does not need an escape window.
One other thing. If the larger bathroom became a bedroom, the original small WC would need upgrading to a shower room. It is almost certainly too small, and the door would need to open outwards to comply with the current regulations.
Sometimes the answer is don't buy it
I am not trying to talk anyone into a project. Quite often the useful answer is that the house won't do what you want it to, or not for the money you have. Three people have described that in their own words.
“I was interested in a house to buy that needed a lot of work done to it. He was able to tell us the work that needed done would almost certainly exceed our budget. Based partly on this insight alone we pulled out of the purchase — and are so glad we did. We feel like we dodged a bullet.”
— Orla McDonnell, Google review
“His professional judgement helped me decide against a property I was considering buying, for good reasons. Super helpful for first time buyers.”
— Lisa Christina Imhoff, Google review
“Informative consultation which saved me from purchasing a property which did not really meet my needs. Taking the time to discuss all my options, Niall provided a voice of clarity and reason.”
— Lucky Lou, Google review
It works the other way too. Sometimes the answer is that your plan is realistic and you should go ahead with confidence.
“We had an extremely helpful consultation with Niall when in the process of buying a property we wanted to modify post purchase, giving us the confidence to proceed with the purchase having clear, realistic ideas of the possibilities. In the context of spending hundreds of thousands on a purchase, the small cost plus half an hour seems like a no-brainer.”
— David Birch, Google review
What I don't do
This is advice, not a design service. You won't receive drawings, a feasibility study or a structural report. It is a conversation with an architect who has read your listing and checked the planning history beforehand, so you know what you are taking on before you commit.
I don't advise on basements, houses in multiple occupation, mixed-use projects, subdividing a property into flats, developing a site into several homes, or commercial property. I don't give detailed construction cost estimates — any figures I mention are broad and exclude VAT — and I can't guarantee that planning permission or listed building consent will be granted.
If the property needs a structural opinion, you need a RICS survey. I will tell you so, and I will tell you what to ask them.
Talk to me about the property you are considering
Everything above describes other people's houses. Yours has its own planning history, its own defects, its own neighbours and its own set of things buried where you want to build.
A consultation before buying a house is £150 for 30 minutes on Zoom, for a property anywhere in the UK. I read the listing, the address and the planning history before we speak, so we spend the time on your property rather than on introductions. Afterwards I send a written summary of what we discussed, including the approvals your project would need and how to brief local architects properly.
Book a consultation before buying a house · Same-day slots are available if you are viewing today or about to make an offer.
“Thanks to the service offered by Niall, I was able to take an informed decision before making an offer on a property. Money well spent. It's great to have impartial professional advice before buying a property.”
— Edward Desouza, Google review
Not ready to book? Download my free guide for UK home buyers — 20 pages on researching a property's planning history, listed status and conservation area restrictions, and what to ask a RICS surveyor.
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