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uk Home & property emergencies crack around window widening • crack around door frame widening • large wall crack getting bigger • sudden structural crack indoors • diagonal crack by window • door frame crack spreading • wall moving around openings • plaster crack widening fast • brickwork crack near window • house movement signs • floor feels uneven suddenly • doors sticking after crack • loud creak then crack appeared • worried house is unstable • possible subsidence crack • possible structural movement • new gap around frame • crack keeps widening overnight

What to do if…
a large crack appears around a window or door frame and keeps widening

Short answer

Treat a widening crack around an opening as a potential structural safety issue: move people away from that area, and if you think there’s any chance of collapse, leave the building and call 999 or 112.

Do not do these things

  • Do not keep “testing” the door/window by forcing it open or shut if it’s sticking or the frame looks distorted.
  • Do not drill, chisel, cut, or remove plaster/brickwork “to see how bad it is”.
  • Do not patch/fill the crack as your first response (it can hide change and delay proper assessment).
  • Do not ignore new warning signs like loud creaks, fresh cracks elsewhere, bulging walls/ceilings, or doors suddenly not fitting.
  • Do not stay inside if you feel unsafe “until someone confirms it” — if you’re genuinely worried, prioritise getting out.

What to do now

  1. Create a safer pause. Get everyone (and pets) away from the cracked area and out of the room below/above it if possible. Keep clear of the wall, the opening, and anything that could fall.
  2. Do a quick “is this an emergency right now?” check. Leave and call 999/112 if any apply:
    • The crack is widening noticeably over minutes/hours, or you hear ongoing cracking/creaking.
    • The wall/ceiling is bulging, bowing, sagging, or shedding debris.
    • A door/window frame looks racked (out of square) or the opening is visibly deforming.
    • Floors suddenly slope, bounce, or feel unstable near the crack.
  3. If you smell gas, hear hissing, or suspect a gas leak: do not use switches or flames, ventilate if safe to do so, leave, and call the National Gas Emergency Service (0800 111 999).
  4. Reduce loads and vibrations (without “fixing”). If it’s safe to remain briefly, stop anything that shakes the area (washing machine spin cycle, heavy footsteps upstairs). Don’t stack items against that wall. Keep children away.
  5. Document what you’re seeing (2–3 minutes, then stop). Take clear photos/video with something for scale (coin/ruler). Note the time and whether it’s changing. If safe, lightly mark the ends of the crack in pencil so you can tell if it grows.
  6. Contact the right “building safety” route for your situation:
    • If you rent: report it immediately to the landlord/agent as an urgent safety repair, in writing (text/email) and by phone if possible.
    • If you own: call your home insurer to report potential structural damage and ask what they require before work begins (many want an assessment and may appoint one).
    • If you believe it may be dangerous to occupants or the public: contact your local council/local authority Building Control (or the local authority’s “dangerous structure” contact route). Many areas offer out-of-hours reporting, but arrangements vary.
  7. Arrange a professional assessment. Ask for an independent structural engineer or chartered building surveyor to assess urgent movement (not a contractor whose income depends on selling a specific repair).

What can wait

  • You do not need to decide today what the “cause” is (subsidence, lintel failure, moisture, etc.).
  • You do not need to book repairs, underpinning, or replacement windows/doors until you’ve had an appropriate assessment (and, if relevant, insurer input).
  • You do not need to cosmetically fix or redecorate anything now.

Important reassurance

It’s common to feel shaken by a changing crack — your brain treats it like immediate danger because sometimes it is. Taking calm safety steps (creating distance, documenting, getting the right people involved) is a sensible response, even if the end result turns out to be less serious than it looks.

Scope note

This is first-steps guidance to reduce immediate risk and avoid costly mistakes. Structural movement can have multiple causes; follow-up decisions should be based on professional inspection and (if applicable) insurer requirements.

Important note

This is general information, not a diagnosis or a substitute for an on-site safety assessment. If you think anyone is in immediate danger, leave and call emergency services.

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