Investigate cracks or subsidence and claim on insurance

This guide is for homeowners in the UK who have found a crack that worries them, or who suspect the house is moving. It shows you how to read the crack, record it in a way an insurer or engineer will trust, look for the usual causes without touching anything structural, and decide when to call your insurer and when to call a chartered structural engineer. If it is subsidence, it then walks you through the claim, from the loss adjuster's first visit to the certificate you will need when you sell. It is general information: never dig near foundations, cut tree roots or attempt structural repairs yourself, and if you rent, tell your landlord rather than claiming.

What is inside

• Full step-by-step method9 detailed steps with decision points
• Ready-to-use templatesCrack monitoring log (copy into a notebook or spreadsheet) · Email to your insurer reporting suspected subsidence · Brief for an independent structural engineer
• Timed action plan8 stages from “Day 1” to “Before selling or switching cover”
• Costly mistakes to avoid4 traps and what to do instead
• Complete checklist12 items to tick off
• Insider tips and fixes4 tips and 4 common problems solved

Step by step

1. Record the crack before you touch anything

   Photograph each crack straight on with a ruler or a crack-width card held against it, then take a wider shot showing where it sits in the room or on the outside wall. Measure the widest point in millimetres and note its length, direction (vertical, horizontal, diagonal or stepped through the mortar) and whether it is wider at one end. Check the same spot on the other side of the wall: a crack that shows inside and outside in the same place is more significant than a plaster-only crack. Do not fill, paint or wallpaper over it yet, because the insurer or engineer needs to see it untouched and filling destroys the evidence (the regular guide to filling cracks covers that job later). If a wall is bulging, a door or window has suddenly jammed, a crack is opening by the day, or you smell gas or hear running water, leave that area, call the gas emergency line or your water supplier as appropriate, and contact your insurer and the council's building control team the same day.