A question of subsidence

John Conlin / 27 October 2016 ( 27 November 2018 )

Chartered Surveyor John Conlin advises against jumping to conclusions.

Question: is a crack in the brickwork subsidence?

A zig zag crack has appeared in the brickwork between the arch over our porch and the window above.

Is this subsidence and will we need underpinning?

How to spot the signs of subsidence


Never jump to conclusions. Too many houses are unnecessarily underpinned and suffer a reduction in value as a result.

No proper diagnosis can be made without detailed professional monitoring over a full cycle of seasons.

Don’t rely on the opinion of an underpinning contractor – that is like asking a fox to count the chickens. Seek a chartered building surveyor or structural engineer.

Question: should I worry about hairline cracks in the plaster?

Some hairline cracks have appeared in the plaster in one room of our house. I’m worried that it might be subsidence. At what stage should I tell my insurers?


Such cracks, particularly after the hot dry summer, could be merely thermal shrinkage rather than subsidence. Unless they start to extend or widen significantly watch them over a full cycle of seasons and you may find that they open and close in response to temperature and humidity. If this is the case they are providing structural stress relief and can be made good with a flexible filler.

Do not alert your insurers until you have had a professional assessment because the insurer will log it as an ‘open claim’ and underwriters may load your premium on renewal even if the claim is not pursued.

For more tips from John Conlin visit the
Chartered Surveyor Q&A section

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The opinions expressed are those of the author and are not held by Saga unless specifically stated.

The material is for general information only and does not constitute investment, tax, legal, medical or other form of advice. You should not rely on this information to make (or refrain from making) any decisions. Always obtain independent, professional advice for your own particular situation.