PROPERTY PROBLEMS: What have the hot weather and subsidence got in common?

...quite a lot actually...

There is no doubt that for the last few weeks we have been enjoying some rather glorious summer sunshine and with the heatwave set to continue into the next few weeks too, 2018 is set to become the hottest summer on record in the UK. However, we know as Essex based Chartered Surveyors, the sunshine doesn't always mean it's rosy in the garden and prolonged periods of warm weather are a sign that home and commercial property owners should look around their properties for signs of subsidence as water and moisture is drained away from the supporting soil.

Surveyors define subsidence as the downward movement of the ground supporting a building, with particular problems occurring when that movement varies from one part of the building to another, producing cracks. Our Essex based extensive Chartered Surveyor experience tells us that it generally affects properties built before the mid 1960's as they tend to have shallow foundations and are therefore more prone to it. The other two main causes are the underlying soil (particularly clay based soil which expands and contracts quite significantly with varying levels of moisture) and the proximity of trees and shrubs to the property. A large oak tree may draw 200 gallons a week from the sub-soil. In fact, the Halifax Home Insurance suggests that between 60-70% of valid subsidence claims involve trees.

Clay sub-soil shrinks slowly as it dries, taking the building down gently with it, but when it becomes wetted again with any significant rainfall, the clay will expand again rapidly, leading to much quicker upward movement (though you cannot perceive it in action), and that is known as “Clay Heave”. Major damage can occur with weaker foundations.

Another factor that can lead to “differential movement” is when an extension is added to an older property that has shallower foundations. The new part having more substantial foundations, there is a risk of the older part moving at a differing rate in respect of that new section, resulting in the joint between them opening and cracking, often noticed between the seasons of the year.

In our 40 plus years of surveying experience, and according to the Financial Ombudsman, the majority of household (and some commercial property) insurance policies cover loss or damage caused by subsidence. Beware though because they may only cover the cost of repairing the loss or damage and not the cost of preventing further subsidence or movement. Some older insurance policy wording did not allow cover for clay heave, resulting in claims being rejected. We have not encountered such omissions in more recent policies.

In reality, to ensure an effective repair that will last for a reasonable period of time, the insurer will usually have to carry out work to stop the movement first (unless it has already stopped) but you may be faced with footing a bill for several tens of thousands of pounds.

If you spot a warning sign of subsidence, even if it seems to be nothing major to begin with it is vital that you call an expert. It will save you a considerable amount of money when getting it fixed as it has been caught early.


Preventative measures include checking pipes and drains regularly to ensure there are no blockages or leaks. A drain leak can undermine foundations, leading to movement or fracture of foundations and the building. If that is the cause, the insurer may argue you failed to maintain the drains, and reject the claim.

Trees should be pruned occasionally to reduce water uptake, and any new trees or shrubs should be planted at a safe distance from your property. How far is safe? Depending on species, you should never allow a tree or large shrub to stand within 10m (or 33 feet) of any structure, but some like willows or black poplar are harmful from greater distances. Remember a small tree or shrub can develop into a hazard later.

If you think you may have, or be at risk from, subsidence then what you should look for are diagonal or stepped cracks – especially around doors and windows. These will usually be thicker than a 10p coin and wider at the bottom. Heave results in cracks wider at the top. If you're not sure about the cracks, in the first instance, get hold of a Chartered Surveyor (look for MRICS or FRICS), who can give you some independent advice.

If you are buying a property, always ensure you have a comprehensive building survey or Homebuyers’ Survey & Valuation report carried out early in the process, as it will provide more time for the investigation of existing cracks. Your home insurance policy could be invalidated or withdrawn if existing cracks not investigated are later established as subsidence.

need to investigate subsidence or other building issues?

Whether you're a business or home owner looking for a Chartered Surveyor in North Essex then do give us a call on 01206 545139.