Greenhalgh & Co.

Chartered Building Surveyors & Valuers

Greenhalgh & Co.

Chartered Building Surveyors & Valuers

21 Towncroft Lane

Bolton  BL1 5EN

Tel: +44 (0)1204 845382

Fax: +44 (0)1204 433968



RICS Company No. 002973


Mine workings

Loss of value due to mining


There are many areas of the U.K. that have been mined for coal and other minerals and substances.  Coal is the most widely extracted substance.  Prior to the advent of central heating, coal was widely used for heating.  A typical terraced house could burn close to its own cubic volume in coal during the course of its life.  In addition coal was the main power source for shipping, the railways and industry. The large majority of the coal was extracted from underground seams. 


It naturally follows that there must be huge voids in the ground where coal mining took place, as none of the mines were filled in.  Water will of course have entered the mines and most will now be flooded, unless there was a natural discharge point, which in most cases there wasn’t.


Many houses in mining areas are therefore constructed above ground which has many voids (albeit voids filled with water). 


Mining subsidence can occur many years after the mine was closed.  Many mines being worked on the room and pillar method rely solely on the remaining pillars to prevent a collapse. If due to earth tremor, fracking, or simply general deterioration due to the weight of earth they support, a failure occurs, then subsidence could ultimately affect any properties built above them.


In our experience the likelihood of subsidence being attributed to a failure in underground mine working is not great. 


The incidence of a failure due to underground mine workings may however be significantly greater than most people believe. 


The reason why a failure may occur, cause subsidence, but not be attributed to a collapse in old workings is as follows:


If for example one looked at the Geological survey of England and Wales 1930 edition for the Horwich and Blackrod area, one would see that coal mining typically took place at a depth range of around 100ft to 1000ft.  A collapse in mine workings 100ft below the surface would likely filter through to the ground surface relatively quickly, the converse being true of a collapse of a mine 1000ft below the surface.


Therefore there will be a significant difference in time frame.


In addition the likelihood of proving that a collapse in mine workings has caused a subsidence event is virtually impossible.  There is no method of gaining access to the workings or proving their condition prior to the subsidence event or after it.


One can complete a Coal Mining Subsidence Act 1991 damage notice.  But what you can’t usually do, is prove that the damage relates to Coal Mining Subsidence.


So in reality it is only the most obvious forms of subsidence damage (mine shaft failure) that will achieve compensation.


This brings us to the issue of whether a property constructed over old mine workings suffers a loss of value due to the same.  Oddly enough the answer that we have found is that there is no loss of value.


A prospective purchaser will receive a Coal Authority report. The report will describe the property as being located above previous workings.  It will however give no indication of the condition of the supports in these workings or their likelihood of failure, simply because this information is unknown. 


And with no indication of the likelihood of a potential threat, no discount will likely be asked for or given.


Should properties built over old mine workings be subject to a discount?


In theory the answer should be less, simply because; a prospective purchaser given a choice between two identical properties one constructed above old mine working and one not; would opt for the one that wasn’t.


However in practice our experience is, that there is no loss in value, most likely because the loss is not quantifiable. If you can’t quantify the discount, you can’t apply it.