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About Mundic
‘Mundic’ - In short, Mundic blocks are concrete blocks which were made using local mine waste and or beach gravel materials, 1900 - 1965*; in Cornwall and West Devon. These waste materials often included elements which can cause failure of the blocks.
Bal maidens working at Wheal Mary Ann Mine
(photos from mindat.org)
Pyrite ('fool's gold')
Mundic in more Detail
‘Mundic’ is a Cornish word used to describe the disulphide mineral of iron generally known as pyrite or iron pyrites (FeS2 ). However, the term is now 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 (RICS Guidance Note - The mundic problem, 3rd Edition, 2015).
Guidance suggests any property built between 1900 - 1950* in Cornwall, and some in Devon; should be tested for mundic (*up to 1965 in parts of East Cornwall). Beyond this, properties which show typical signs of mundic related cracking may be identified for testing.
Because mundic blocks were produced local to the mines around Cornwall and Devon, those locally made blocks contain different mine waste elements to other areas. For example, locally made mundic blocks around South East Cornwall are likely to contain lead ore mine waste from the Wheal Mary Ann Mine near Menheniot.
Not all mundic is problematic. Indeed, it is known that some properties with Wheal Mary Ann derived mundic blocks, for example, are considered sound, whilst other properties with the same mundic blocks are considered unsound; requiring demolition. The method for demonstrating the soundness of mundic block is petrographic analysis. This identifies the various constituent elements in the block, and their potential for degradation / failure.
The testing and analysis procedure is fairly straight-forward, so long as it is all conducted in a prescribed and logical manner. The Royal Institution of Chartered Surveyors (RICS) neatly lay out the guidance for this in their publication - The mundic problem, 3rd edition, 2015. The taking of core samples from the accessible walls, foundations and alike of suspect properties is undertaken under the supervision of a Chartered professional, and all core samples properly recorded. These samples are next taken to the laboratory for analysis. The qualified Mineralogists will then classify the grade of mundic. We will receive the Data from the laboratory, and this will show what classification of mundic the core samples are. Currently, the classifications of mundic are as follows - A1, A2, A3, B, C1, C2. In short, only Classification A mundic is considered 'sound and mortgageable. 'Sound' mundic is that which is 'showing no, or only rare evidence of deterioration and in either case exhibiting properties which are considered unlikely to adversely affect future concrete performance, subject to regular protective maintenance.'
Ways of dealing with Mundic?
As mentioned earlier, not all mundic is a problem. Where it can be demonstrated as 'sound', it can be left alone. For example, Classification A1 mundic has no mundic, A2 has some mundic but has passed a Stage 2 analysis; and A3 mundic has likewise some mundic but passed a Stage 3 analysis. These are generally considered mortgageable. Clasification B, C1 and C2 are less favourable to Lenders. So what are the realistic options for mundic property owners / buyers?
Leave it alone - where the testing and analysis demonstrates a sound, mortgageable property, the property owner may simply wish to do nothing, except maintain the property in good order. This would be a logical and reasonable position.
Remove the mundic and build new walls - sometimes only part of a property is burdened by mundic block. For example, you might own an 1890 built property, of brick or stone construction; with a later extension built of local mundic block. If that mundic element is unsound you may wish to consider removing the mundic and constructing new, replacement walls. We can do this for you.
Total demolition followed by construction of a new home - where your property is largely or wholly constructed of unsound mundic block, or mundic which has potential to fail; you may consider the merits of replacing the property with a brand new building. Whilst this is subject to Planning, Building Control and financial considerations, there is clearly many persuasive arguments to favour this. A newly constructed, well designed, well insulated, well considered home may be an attractive and not so unrealistic option. We can do this for you.
Moving forward
For all your mundic requirements, from initial survey, testing and analysis, and partial and or full rebuilds; Mundic.co.uk are here to help you. We do all things Mundic, under one roof.
We handle all the necessary paper-work. This keeps all files in good order, for audits, Mortgage lenders, insurers, inspecting Building Control Officers and alike. Above all, you are reassured your mundic requirements are taken care of by a Chartered led company. We are ethical, approachable and affordable. And we will work with you in a straight-forward, down to earth, and practical manner.