Monitoring - Is it all it’s Cracked up to be? - Chris Miller

Generally extraneous causes such as trees or drains are firstly dealt with and then monitoring is undertaken. It is as if monitoring is the panacea for success. Whilst monitoring is usually a scientific method with factual results the period of monitoring and the interpretation of the results are subjective. As an ingredient to subsidence claims, monitoring is not a true the litmus test. With monitoring being subjective a rule book on interpretation of monitoring results is impossible.

The principle of indemnity is to return a policyholder to the same position as existed prior to the loss. It is assumed that prior to the damage stability existed and therefore an acceptable indemnity results where the repairs leave the policyholder with a stable property.

Monitoring is accordingly to establish whether stability has returned or a position of unacceptable instability exists. Both of these are subjective decisions. As most subsidence claims involve cracks of minor widths so interpretation of monitoring results is inherently difficult. Engineers have often argued that 0.1mm of movement is proof of ongoing instability and accordingly underpinning is warranted. The loss adjuster will usually resist such an argument despite the monitoring. If the monitoring is by a levelling survey similar arguments can still arise over minor movements and the need or not for underpinning.

BRE Digest 251 is often taken as the bible in the context of crack measurements and commonly adjusters in their reports to insurers categorise the cracks per the Digest as follows:

The Digest suggests that if a crack moves up a category then instability exists and sub-structural works are justified. Whether such instability is unacceptable is not addressed.

Monitoring compares the crack widths to the widths at commencement. A crack of 0.95mm increasing by 0.15mm to 1.1mm represents an increase of 14% but by moving from Category 0 to 1 the property is unstable. 1.0mm of movement to an original 5.0mm crack, elevating the crack from Category 2 to 3 represents an increase of 20% yet again the Digest would suggest underpinning is required. However 1.0mm increase to an original crack of 1.0mm represents an increase of 100% but the crack still remains within Category 2 and no underpinning would be considered. On face value an increase of 100% appears far more dramatic than 14% or 20% yet the outcome on repairs may be far different. Should therefore the Digest be disregarded?

With increases in crack width the question is whether the degree of movement would have caused a crack in the absence of the one under monitor. If the answer is yes then the question is whether the degree of movement causing the hypothetical new crack would render the property intrinsically unstable. We are then back to subjective arguments.

Where a crack under monitor is wider than at the commencement of the monitoring then on a year in/year out basis the damage is worsening and the property could be said to be unacceptably unstable. However the increase in width following the above examples of 20% to 100% gives no clear determination on instability.

In 2005 CIRIA released a book on climate change risks to buildings. It was aimed inter alia at adjusters and the insurance industry with specific regard to the future risks of principally storm and subsidence.

“Minor” movement is not defined and certainty on no worsening of the situation cannot be possible. Reference to “cosmetic cracks” implies cracks within the finishes. Again interpretation is open to dispute.

This book identified appropriate action with subsidence damage as follows:

The CIRIA book also addressed global warning and its effects on buildings. Data showed changing weather patterns. With global warming, which is clearly occurring, the seasons are now blurring into each other. However it is common for monitoring to be advocated over a period of at least three seasons. The water content of cohesive soils, the common trigger for subsidence, increases in winter due to a reduction in leafage and therefore water demand from the roots of trees and foliage and decreases in the summer months when shrinkage is at its greatest. Trees are often now keeping their leafage right into December and as witnessed this year buds are appearing in January and plants are leafing already. Summer months are in fact showing an increase in rain fall. In some current cases monitoring over the winter has in fact shown an increase in crack widths following a dry winter after the wet summer of 2007. The rationale for monitoring over winter/summer months is therefore rapidly fading.

The Building Research Establishment has shown epoxy resin crack repairs are stronger than the wall itself and more resilient to the tension stresses such that subsidence induces. Further movement is therefore more likely to cause new fractures in different locations than the previously repaired cracks. This is a far more definite proof of ongoing movement and unacceptable instability.

With seasons blurring and the interpretation of monitoring results open to question it may therefore be better to dispense with monitoring altogether, deal with any extraneous causes and simply then proceed straight to superstructural works with proper crack repairs. With no engineering proof that such an approach is failing to provide indemnity under the policy this would resolve the majority of claims. The life cycle of the claim is reduced substantially and policyholders are back with the original property much quicker and can resume normal occupation without an extended monitoring period hanging over their heads, often lasting well over a year, before repairs are considered and then with the potential of argument over the nature of such works.

Some properties may well move again in the future and in such case insurers, where new cracks have appeared in the structural fabric, will then be faced with underpinning. Obviously a time scale will attach if no new excess is to be applied but insurers are already giving such terms of assurance.

Chris Miller FRICS FCILA FBEng MCIArb