UK Mundic Problem

The UK MUNDIC Problem

Last updated 25.07.15

The problem, as described by Bromley and Pettifer (1997):

“Mundic was a local Cornish word used to describe the disulphide mineral of iron generally known as pyrite or iron pyrites (FeS2), but it has become a term widely used to describe a cause of deterioration in concrete, resulting from the decomposition of various aggregate mineral constituents of which iron pyrites is but one”

Cornwall Council (2015) provides further information on the problems encountered:

“Many properties in the South West of England are built from concrete blocks laid onto mass concrete foundations. Blocks were produced from waste rock worked from mining, quarrying and free supplies of beach gravel. The production of the blocks using these materials took place from the turn of the twentieth century until the 1950s when mass production of widespread concrete blocks became common. This did not totally eradicate the use of local materials in block and foundation construction until the early 1960s. Some of these local materials used as aggregates in concrete construction can cause deterioration and mechanical weakening of the building.”

The following historical summary is a working progress which details the UK Mundic problems. The summary includes notes on:

  • Cases of Mundic problems
  • Publications, research and conferences relating to the Mundic problem
  • Technical documents and guidance
  • Examples of where mortgage lending terms exclude Mundic properties

Sources and Disclaimer

I have tried to link to information sources for each event. If not linked, the source and date of the article (where applicable) is given. The summary does not purport to be complete and whilst I have made every effort to ensure accuracy, mistakes are possible. Caution should be exercised when reading and interpreting these events. Any interpretation or use is at the reader’s risk. Attention should be paid to the original source and its validity. I am not responsible for content hosted outside of Please get in touch with any corrections, additions or revisions. I welcome any feedback and comments.

Historical Summary


July: Cornwall Council updates guidance page on Mundic problems. Click to read the “Guide to Mundic Block”. (24.07.15).

May: Foundation Home Loans updates their Underwriting Guidelines. The terms notes that ‘Some property types will always be unacceptable to the Company.” [including] “…concrete block construction designated Mundic.” Click here to read terms.

April: Martin Roberts posts article on Mundic block – Crumbling investment or Cornish bargain? Click here to read article. (02.04.15).

March: RICS posts article and download link for the Mundic problem guidance note (3rd Edition) online. Click here to read post. (23.03.15).

March: TSB updates their criteria guide. Includes “Concrete walls as built in Cornwall or Devon before 1950 (1960 for postcodes PL12, 13, 14, 15, 17, 18, 22 & 23) where valuer has recommended a Mundic report and test of the concrete has classified the concrete in either class B or C” within the unacceptable construction types. Click here to read terms. (18.03.15)


May: Skipton Building Society, in their valuation guidance notes for panel valuers, states that “Properties of “mundic” construction are not acceptable to the Society”. Click here to read online.


November: Mortgages Direct update their lending criteria. Lending product “Kensington” not considered on “…properties containing mundic block materials…” Click here to read terms.

September: Royal Institute of Chartered Surveyors publishes draft guidance note – The Mundic Problem (3rd Edition). Click here to read online. Draft guidance published for public comment on 19.09.13.

January: Precise Mortgages publishes its Criteria Guide and includes “any property containing Mundic concrete” within its list of “unacceptable property types”. Click here to read terms. (30.01.13).


November: The Guardian reports that ‘”Mundic block can chip 25% off the value of properties in the south-west, as mortgage borrowers are discovering to their cost”. Click here to read article. (29.11.09).


Document published: RICS. (2005). The “Mundic” Problem – Supplement to Second Edition – Stage 3 Expansion Testing. The Royal Institution of Chartered Surveyors, UK.

February: RICS posts article and download link for the Mundic problem guidance note (2nd Edition) online. Click here to read post. 03.02.05.

January: Money Market reports that “Cornish IFA sets up firm after lenders put the block on mundic mortgages”. Money Market (20.01.05).


February: The Telegraph features an article/case study on a house with mundic-type problems in Cornwall. Click here to read article. (11.02.04).


Report published which considers some of the pyritic aggregates in Southwest England: Bromley, A. (2000). A compendium of concrete aggregates used in Southwest England. Petrolab, UK. Click here to read full PDF online.

December: The Telegraph reports on “Homes in Cornwall are being eaten away by a disease that is a legacy of the old tin mines”. Click here to read article. (03.12.00).


Document published: RICS. (1997). The ‘‘Mundic’’ Problem—A guidance note (2nd ed.). Royal Institution of Chartered Surveyors, London. Click here to read full PDF online.

Document published: Bromley, A., and Pettifer, K. (1997). Sulfide-related degradation of concrete in Southwest England (The Mundic problem). BRE Laboratory Report 325. Building Research Establishment.


Paper published: Lugg, A., and Probert, D. (1996). “Mundic”-type problems: a building material catastrophe. Construction and Building Materials. 10 (6), 467-474. Click here to read abstract.


Document published: RICS (1994). The ‘Mundic’ Problem: A Guidance Note—Recommended Sampling, Examination and Classification Procedure for Suspect Concrete Building Materials in Cornwall and Devon. The Royal Institute of Chartered Surveys, Surveyors Holdings Limited, London.


Report published: Building Research Establishment (BRE). (1992). Taking care of “mundic” concrete houses. BRE, Bracknell.


July: Matthew Taylor asks the Secretary of State for the Environment “if he will obtain for his departmental library a copy of the 28 June edition of the “Construction Journal” article concerning Mundic aggregates ; and if he will make a statement.” Read the question and response here. (11.07.90).


Paper published: Catt, R. (1989). Mundic – its effect on 2,000 houses in Cornwall. Structural Survey. 7 (2), 152 – 159. Click to read more.


Document published: Technical Report on Mundic Block, Cornwall, United Kingdom (Metric Edition) TH Goldschmidt A. G., Chemische Fabriken, Essen, Germany (1986) (Report ref. 3075). (Referenced in Lugg and Probert 1996 paper)