How do I know if I’ve got serious structural subsidence OR a serious structural issue in the HA5 area?

How do I know if I've got serious structural subsidence OR a serious structural issue in the HA5 area?

Friday 4th December 2020

This is a question that we at TAYROSS ASSOCIATES LTD chartered CIOB and RICS surveying practice, often get asked by worried homeowners.

Homeowners get nervous when they start to see cracks appearing in their property that wasn't there before.

Sometimes this concern is justified but on many other occasions, we find that it is nothing to be worried about.

95% of cracks that appear in properties are not connected with subsidence or heave (where the soil beneath a property expands and pushes the ground upwards). In most instances, they are down to differential thermal expansion and contraction.

The biggest cause of cracking in the HA5 area is related to the highly shrinkable London clay that most properties are founded on and foundations in close proximity of trees that require or have a high propensity to remove water from the clay, causing shrinkage and foundation movement. This normally occurs with hot summers of which we are getting more of.

The rule of thumb is not to have trees closer to your property than that of the distance from their trunk to the property and this should not be less than their height.

A lot of the properties in the HA5 area are 1930s with old clay socket and sprocket joints. These are particularly prone to leaking which draws roots from as far away as 50 metres to their area, unfortunately, most train lines run close to foundations and this is where the problem begins.

If you are concerned about cracks that have recently appeared, I would recommend carrying out an SSI (specific structural investigation) report which we at Tayross Associates can arrange at a reasonable cost.