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What to do if…
a new crack appears in a wall or ceiling and seems to be widening

Produced and maintained by PanicStation.org Published: Last reviewed: Editorial policy UK guide

Short answer

Keep people away from the affected area and treat a widening crack as a possible safety issue until it has been assessed, especially if anything is sagging, bowed, leaking, falling, or making new cracking noises.

Do not do these things

  • Do not ignore a crack that is clearly widening, lengthening, or changing quickly.
  • Do not drill, cut, chase, scrape back, or knock plaster off around the crack to see what is underneath.
  • Do not attempt DIY jacking, bracing, or propping of walls or ceilings.
  • Do not sleep, sit, or stand under a cracked ceiling if it is bulging, sagging, damp, or shedding plaster.
  • Do not add weight above or near the affected area, such as storing heavy items in a loft over a cracked ceiling.
  • Do not let anyone start structural work without advice from a suitably qualified professional if there are signs of movement.

What to do now

  1. Move away from immediate danger. If you believe there is a risk of collapse, falling material, fire, serious injury, or danger to people outside the property, move to a safer place and call 999.

    • Examples include a bulging or sagging ceiling, falling debris, loud new cracking noises, a bowed wall, a sudden major change in doors or windows, or a crack near stairs, a beam, or an outside wall.

  2. Create a no-go zone. Keep people and pets out of the affected room or area. If the crack is in a ceiling, do not stand, sit, or sleep underneath it.

  3. Check briefly for gas or water hazards, only if it is safe.

    • If you smell gas or suspect a gas leak, get fresh air and leave immediately. If you can do so on the way out without delay, open doors and windows. From outside, call the National Gas Emergency Service on 0800 111 999. Do not smoke, use naked flames, or operate electrical switches.
    • If water is leaking through or near the crack, turn off the water at the stopcock if you can do so without going under the damaged area. Move people and valuables away from the leak.

  4. Record what is changing. Take clear photos or a short video from a safe distance. Include something for scale, such as a ruler or coin. Note the date and time you first saw the crack, how fast it appears to be changing, and any recent trigger such as heavy rain, a plumbing leak, nearby building work, impact, or a loud bang.

  5. Mark and measure it only if you can do so safely. Lightly pencil-mark the visible ends of the crack and write the date next to the marks. Measure the widest point. Re-check later the same day or the next day if the area remains safe to approach.

  6. Report or arrange an urgent assessment.

    • If you rent, tell your landlord or letting agent immediately in writing and ask for an urgent inspection. Include photos, the date, and any safety concerns. If you think the property may be unsafe and you cannot get a prompt response, contact your local council for the dangerous structures, building control, housing, or environmental health route.
    • If you own the property, contact a suitably qualified professional, for example a structural engineer or chartered surveyor who deals with building movement. If you have buildings insurance, contact your insurer after the immediate safety issue is controlled and before arranging intrusive repairs, unless delay would make the situation unsafe.

  7. Use the local dangerous-building route if the structure may be unsafe.

    • In England and Wales, dangerous building or structure reports are made through the local council.
    • In Scotland, dangerous building reports are usually handled by the local authority building standards service.
    • In Northern Ireland, the local council is usually the first point of contact for dangerous, derelict, or insecure buildings.

What can wait

  • You do not need to decide today whether the cause is subsidence, settlement, old plaster, water damage, vibration, or a structural defect.
  • You do not need to choose a repair method, redecorate, or accept a contractor’s quote before the movement has been assessed.
  • You do not need to settle arguments about who is liable right now. First focus on keeping people clear, recording the change, and getting the right assessment.

Important reassurance

Many cracks turn out to be cosmetic or related to normal movement, plaster, moisture, or past work. A crack that is widening still deserves calm, prompt action because keeping clear, documenting it, and getting it checked can reduce risk and prevent rushed decisions.

Scope note

These are first steps only. Later decisions may need help from a structural engineer, chartered surveyor, insurer, landlord, local council, or other specialist depending on what the inspection finds.

Important note

This is general information, not legal, medical, financial, surveying, engineering, or other professional advice. It is not a diagnosis of the crack or a guarantee that the building is safe. If you think anyone is at immediate risk, move to a safer place and contact emergency services.

Additional Resources

Closely connected guides that may be useful during the same situation or its immediate aftermath.

About this guide

This guide was produced and is maintained by PanicStation.org using its published editorial process. Official and specialist sources are checked where relevant, and AI-assisted tools may be used for drafting, organisation, and consistency checks. The site operator remains responsible for publication, revision, and removal decisions.

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