Crack and movement monitoring means measuring cracks, and sometimes floor or wall levels, at regular intervals so a chartered structural engineer can tell whether a building is still moving, and whether that movement is seasonal or getting steadily worse. The RICS consumer guide on subsidence notes that monitoring may need to run for around 12 months or longer. It is often the step that decides whether a house needs repair at all, and what kind.
Why monitor a crack instead of repairing it?
A crack is a record of movement that has already happened. On its own it cannot tell you whether the building is still moving. Many houses across Liverpool and Merseyside carry cracks from settlement decades ago that have not changed since; others are moving now. Repairing the wrong one wastes money, and repairing a crack while the cause is still active simply means it reopens.
BRE Digest 251 grades crack damage from 0 to 5, and BRE is clear that width is not the only factor: whether cracks are getting wider over time matters. Monitoring answers that question with measurements rather than guesswork.
Please do not fill and paint over cracks that are being monitored, or before the cause is known. Covering them hides the evidence the engineer needs, and hiding past movement from an insurer, buyer or lender can cause serious problems later.
Seasonal or progressive movement?
On shrinkable clay, which covers parts of Merseyside, the ground can dry and shrink in summer then swell back in winter, especially near trees. Cracks then open and close with the seasons. Progressive movement is different: the crack keeps widening, year on year, because something such as a leaking drain or a weak foundation has not been dealt with.
| Seasonal movement | Progressive movement | |
|---|---|---|
| Pattern in readings | Opens in dry months, closes in wet months | Widens steadily, with or without a seasonal swing |
| Commonly linked to | Trees and shrubs drying clay soil | Leaking drains, washed-out soil, inadequate foundations |
| Why a long period helps | Shows a full wet and dry cycle | Separates a genuine trend from seasonal noise |
That is why short monitoring periods can mislead. Readings taken only over one winter might suggest everything is stable when the summer shows otherwise.
What methods are used?
- Tell-tale gaugesTwo overlapping plastic plates fixed across a crack, with a grid that shows horizontal and vertical movement at a glance.
- Calibrated studsSmall metal studs fixed either side of a crack and measured with a calliper or gauge for more precise widths.
- Level monitoringSurvey readings taken on points around the building to show whether parts of it are rising or falling relative to each other.
- Photographs and recordsDated photographs and a written log of where each crack runs, how wide it is and any new cracks.
The engineer decides which cracks to monitor, which method to use, how often readings are taken and how long the programme runs. The engineer also interprets the results; a list of numbers is only useful once someone qualified has read it against the building and its surroundings.
What you can do while you wait
There is plenty a homeowner can safely do while monitoring is under way, without touching the structure:
- photograph cracks with a date and a ruler or coin for scale, so changes are easy to spot;
- note doors and windows that start or stop sticking, and when;
- keep gutters, downpipes and gullies clear so extra water is not soaking the ground;
- avoid starting building work or tree work nearby without advice, and check with your council before any tree work in case of a Tree Preservation Order or conservation area;
- contact your buildings insurer if you think the cracking may be subsidence.
If a crack starts opening quickly, a wall leans noticeably or a door frame or ceiling looks unsafe, do not wait for the next reading. Keep people away from that area and get urgent professional advice.
Monitoring and insurance claims
On a subsidence claim, the insurer and its loss adjuster or engineer usually decide whether monitoring is needed, who carries it out and for how long. It is common for monitoring to run before any decision is made about removing the cause or repairing the building. We never promise how an insurer will respond, but our subsidence insurance claims page explains how the process tends to run.
What happens when monitoring ends?
The engineer reviews the readings and reaches a view. Common outcomes are:
- Stable. Movement has stopped or is minor, so cracks can be repaired and the house redecorated, perhaps with crack stitching where masonry needs tying back together.
- Seasonal, linked to a tree or drain. The cause is dealt with first, for example a drain repair or arboricultural advice, then the cracking is repaired. Drain-related cases are covered on our drainage-related subsidence page.
- Progressive, cause cannot be removed. Further investigation and a designed repair follow, which in a minority of cases is underpinning. Our subsidence repair page sets out the options.
Any repair that follows is designed by a chartered structural engineer and carried out by us to that design, with Building Control involved where the Building Regulations apply.
What affects the cost of monitoring?
The number of cracks and monitoring points, the method, how often readings are taken, how long the programme runs and the engineer’s reporting all affect cost. Where monitoring is part of an insurance claim, the insurer arranges it. Repair costs are covered in our underpinning cost guide.
Where we work
We cover the whole of Liverpool and Merseyside. Monitoring questions often come from Victorian and Edwardian houses with bays and cellars in Aigburth, mixed older and inter-war streets in West Derby, and terraces and semis in Old Swan. Monitoring is often the step before any decision on underpinning in Liverpool homes.
Want to know if your cracks are moving?
Call 07777 659786 or leave your details. Tell us where the cracks are, roughly how wide they look and whether they have changed, and we will call you back about the right next step for crack and subsidence repairs across Merseyside.
Frequently asked questions
How long does crack monitoring take?
It is often around 12 months, and sometimes longer, so the engineer can see a full cycle of wet and dry seasons. A shorter period may be enough if movement is clearly stable or clearly worsening. The engineer sets the length based on the building, the likely cause and what the readings show.
Can I monitor cracks myself?
You can and should keep dated photographs and notes, and a pencil line at each end of a crack helps you notice growth. Those records are useful to an engineer. Formal monitoring with gauges or studs and level readings, and its interpretation, should be set up and read by a chartered structural engineer.
What crack width is a concern?
RICS says cracks that appear suddenly and are wider than 3 mm are the main cause for concern, and BRE treats damage up to about 5 mm as usually aesthetic. Width is only part of the picture, though: a narrow crack that keeps widening can matter more than a wider old one that has stopped.
Should I fill the crack while it is being monitored?
No. Filling or painting over a monitored crack hides movement and can disturb gauges. Leave it alone until the engineer has finished and the cause is known. The crack can be properly repaired once the engineer is satisfied the building is stable or the cause has been dealt with.
Does my insurer arrange monitoring?
On a subsidence claim, the insurer and its loss adjuster or engineer usually decide whether monitoring is needed and arrange it. Contact your buildings insurer first if you suspect subsidence. Outside a claim, a homeowner or buyer can ask an engineer to set up monitoring independently.