Signs of subsidence in older London homes can be worrying, and this guide from IQSURV, a RICS regulated firm, explains what buyers should look for and when to ask for advice.
Spotting the signs of subsidence early
Not every crack means movement, and many are cosmetic or long-standing. A surveyor can comment on what is visible and recommend further investigation where it is warranted, which is far better than guessing before you buy.
Cracks and sticking doors can make any buyer nervous. Some are harmless, but others can point to subsidence or ongoing structural movement. Knowing the signs of subsidence helps you decide when to ask more questions before you commit to a purchase. This guide explains what to look for in London homes and when to get professional advice.
What subsidence and movement mean
Subsidence is when the ground beneath a building moves downwards, taking part of the foundations with it. Much of London sits on clay soil, which shrinks in dry weather and swells when wet. Nearby trees, leaking drains and dry summers can all make this worse. Not all movement is subsidence, though. Many older homes have settled years ago and are now stable, and small cracks can also come from normal expansion, shrinking plaster or heat changes.
Common signs of subsidence
- Diagonal cracks in walls, often running from the corners of doors and windows
- Cracks that are wider at one end than the other
- Cracks wider than a few millimetres, or cracks that have been filled and reopened
- Doors and windows that stick or no longer close properly, without an obvious reason such as swelling
- Gaps between skirting boards and floors, or between walls and ceilings
- Wallpaper rippling or tearing where walls meet
- Cracks visible both inside and outside in the same area
- An extension or bay window pulling away from the main house
Signs that are usually less worrying
Fine hairline cracks in new plaster, small cracks where walls meet ceilings and minor cracking around lintels are common and often cosmetic. Even so, it is worth noting where they are and whether they appear to be getting bigger. A pattern of cracking is usually more telling than a single crack on its own.
Look at the surroundings too
Check for large trees close to the house, including in neighbouring gardens, and ask whether any have been removed recently. Look for signs of leaking drains or gutters near the walls, and for damp patches, which can go hand in hand with drainage problems (see our damp checklist for London homes). Ask the seller whether the property has had subsidence before, whether there has been an insurance claim, and whether any underpinning or monitoring has taken place. Past problems do not always mean a home should be avoided, but they can affect insurance and resale.
How a survey helps
A RICS Level 2 survey will flag visible cracking and movement and tell you if further investigation is needed. For older, extended or larger properties, or where there are already signs of movement, a Level 3 survey gives a more detailed look at the structure and the likely causes. Where the surveyor has concerns, they may recommend a structural engineer, a drainage survey or a period of crack monitoring before you exchange contracts.
Get a survey from IQSURV
IQSURV is a RICS regulated firm covering London. Call 020 3780 5386 or visit Unit 107, 401 Edgware Rd, London NW2 6GY to arrange a Level 2 or Level 3 survey. Not sure which you need? Read Level 2 or Level 3 survey. This article is general information, not legal, insurance or structural engineering advice.
Next steps after reading about signs of subsidence
If this guide on signs of subsidence raises questions about your own property, you may find our guides on Level 2 or Level 3 survey guide and damp checklist for London homes useful. The Royal Institution of Chartered Surveyors sets professional standards for the industry, and you can read more on the RICS website. To discuss your situation, get in touch or request a quote through our home page, or call 020 3780 5386.