Subsidence, settlement and heave
How is a bowing wall different from a wall that has cracked but stayed in line?
A bow is the wall leaving the vertical line, often over a whole storey or at the top. A crack can exist in a wall that is still straight. The bow is the more serious description because it means the wall itself has distorted, not only that a joint has opened. A survey photograph of a crack does not show a bow unless the line of the wall was looked at.
Last reviewed 24 October 2026. Written for buyers in England and Wales unless this answer says otherwise. No named surveyor has signed this page. It is general guidance, not a report on your house, and not legal advice.
What is the fuller explanation?
Causes include roof spread, failed ties, a rotten wall plate, or ground movement. They are not one repair. The surveyor should say where the bow is: mid-wall, at the eaves, or from the ground up. That location is the clue. RICS surveys do not usually set up a plumb line on every elevation, so “appears to bow” means a visual judgement. If the decision depends on it, an engineer can measure it.
The ABI subsidence note does not cover every bow. Tie failure and roof spread are not ground movement. Ask which cause the surveyor thinks fits, and what they could not see. Do not average them into “structural problems £20,000”. There is no such figure in the RICS guide. Get an engineer’s recommendation first.
What should you ask your surveyor?
- Where is the bow: eaves, mid-height, or from the ground?
- Is the wall cracked as well as out of line?
- Did you measure it, or is this a visual comment?
What are the typical next steps?
- Stand back and photograph along the wall. A close-up of a crack hides the bow.
- Do not tie the wall with brackets before an engineer has said why it moved.
- Match the next instruction to the cause. Ties, roof and foundations are different firms.
Costs vary with the building and with who you instruct. Where this page does not cite a published figure, ask the surveyor, a relevant specialist, or your solicitor for a written quote. Do not treat a forum average as the price.
Also asked about this
Is a bulge in render a bow?
Render can bulge off the wall while the masonry is straight. Tapping it tells you more. Ask the surveyor which they mean.
Can a bow be historic and stable?
Yes. Old movement can have stopped. The survey cannot promise that from one visit. An engineer may still want to know the cause.