What to Look for When Buying a Renovation Property in London
1. Structural Integrity: The Foundation of Everything
One of the biggest mistakes renovation buyers make? Focusing on finishes and ignoring the bones of the building. A property’s structure should always be your starting point — because if it’s not sound, your entire renovation budget could be swallowed by unseen issues.
What to look for:
Cracks in walls, especially diagonal cracks above windows or doors — these could suggest movement or subsidence.
Sagging or uneven floors that indicate potential joist or subfloor problems.
Doors and windows that stick — not always a carpentry issue; it can signal shifting foundations.
Bowing brickwork or chimney stacks — which may require rebuilding or steel reinforcement.
Subsidence, settlement, and structural movement can cost anywhere from £5,000 to £50,000+ to repair, depending on severity.
🔗 RICS guide to subsidence
Get a full Level 3 Building Survey if you're considering a property that’s older, visibly distressed, or has been unoccupied for long periods. These in-depth surveys assess structure, walls, roof, floors, and foundations — and can reveal hidden problems that typical mortgage valuations miss.
2. Damp and Moisture Problems
In London, damp is one of the most common (and costly) problems in older homes — often misdiagnosed or poorly treated. Moisture can enter a property in many ways: rising from the ground (rising damp), penetrating through walls (penetrating damp), or forming due to poor ventilation (condensation damp).
What to look for:
Musty smells, even if you don’t see visible mould.
Tide marks or brown stains low on walls — classic signs of rising damp.
Black mould patches, particularly in corners, around windows, or behind furniture.
Flaky or bubbling paint and crumbling plaster.
Left untreated, damp can cause timber rot, plaster degradation, mould-related health issues, and long-term structural damage.
Which? reports that damp issues can reduce property value by up to 20% — but many causes are treatable if caught early.
🔗 Which? – How to identify and fix damp
Hire a specialist to carry out a damp survey, not just a general home inspection. They’ll identify the root cause (not just the symptoms) and recommend appropriate treatments — whether that’s a new DPC, improved drainage, or mechanical ventilation.
3. Potential for Layout Changes or Extensions
One of the big appeals of a fixer-upper is creating your ideal layout — knocking through rooms, adding bedrooms, or even extending out or up. But not every home is easily (or legally) adaptable.
What to check:
Is the wall you want to remove load-bearing? If so, you'll need a structural engineer and building control approval.
Head height in the loft — you need at least 2.2m for a comfortable conversion.
Garden depth and space for rear or side extensions.
Access for builders and materials — terrace houses without side access can complicate construction.
Local restrictions — Is the property in a conservation area? Is it listed? Are there Tree Preservation Orders (TPOs)?
Most minor works fall under Permitted Development, but larger changes require planning approval.
🔗 Planning Portal – Do you need permission?
Check with the local planning authority before you buy. You can also search the property's planning history to see what’s been proposed (and rejected) in the past — a good indicator of what might be possible.
4. External Condition: Roof, Windows, and Drainage
It’s easy to fall in love with kerb appeal or the idea of “just replacing the kitchen.” But before you spend on interiors, you may need to address costly exterior work.
What to inspect:
Roof – Look for slipped tiles, patchy repairs, or sagging ridge lines. Water ingress here can lead to rot or mould inside.
Windows – Original sash windows look beautiful but can be draughty, single-glazed, or rotten. Replacements are costly and may need to be like-for-like in conservation areas.
Drainage – Look at downpipes and gutters. Overflow or staining suggests blockages or misalignment.
Brickwork – Check for spalling bricks or eroded mortar, especially on exposed elevations.
Replacing a roof in London can cost between £5,000 and £15,000+, depending on size and materials.
🔗 Checkatrade – New roof cost guide
Budget for the shell first. A warm, dry, structurally sound home is your priority — then you can get creative with interiors.
5. Electrics, Plumbing & Heating Systems
These “invisible” systems make a huge difference to your comfort, safety, and energy bills — and they’re often overlooked during viewings. If a property hasn’t been updated in decades, it’s likely not up to current standards.
Red flags to watch for:
Old fuse boxes with rewireable fuses.
Surface wiring or outdated sockets.
Single radiator or electric heaters — could suggest a lack of central heating.
Lead pipes or corroded plumbing — a health risk and a nightmare to replace.
Rewiring a 3-bed house can cost £4,000–£6,500, and a new heating system may run £3,000–£5,000.
🔗 Checkatrade – House rewiring cost
Ask for certificates (EICR for electrics, gas safety for boilers). If these aren't available or up to date, factor full replacement into your budget.
6. Budgeting & Timeline Expectations
Renovating is exciting — but rarely straightforward. Expect the unexpected.
According to Homebuilding & Renovating Magazine, homeowners underestimate costs by 10–20% on average. For older homes, it can be more if structural, damp, or planning surprises crop up.
🔗 Homebuilding.co.uk – Common renovation mistakes
Key budgeting tips:
Add a contingency fund of 15–20% minimum.
Get multiple quotes for key jobs — prices can vary widely in London.
Be realistic on timelines — planning, sourcing trades, and supply chain delays can push things back.
If possible, phase your renovation. Focus on making the home safe, dry, and liveable before diving into design details.
Need Expert Eyes Before You Buy?
Buying a renovation property is a bold move — and if done right, it can lead to your dream home or a very smart investment. But it pays to go in with your eyes wide open.
We can help you make a confident decision with:
✅ Pre-purchase surveys (Level 2 & Level 3)
✅ Specialist damp and structural assessments
✅ Feasibility reviews for renovations and layout changes
✅ Full project management and construction services
📞 Get in touch for a no-pressure consultation. We’ll help you assess the property honestly, budget smartly, and avoid costly mistakes.
We are fully RICS-qualified Chartered Surveyors, so you can trust that every survey meets the highest industry standards. Whether you’re a first-time buyer or seasoned investor, we provide the clarity and confidence you need — before you buy.
