Mundic Block – Jargon Buster

Mundic is a Cornish word for the mining waste Pyrite. As mining waste was used to produce building materials between 1900-1960, Mundic found its way into properties in the South West. Over time Mundic can cause decay within concrete which is why your lender will ask you for a Mundic report if any part of the property you are purchasing was built between 1900-1960 with concrete block. A Mundic surveyor will take block samples from the property, analyse the concrete and write a report that confirms if the property is mortgageable. There are different report classifications that states if a property mortgageable or not.

Testing for mundic block – The test consists of a two-stage analysis and a stage three performance assessment.

Preliminary Screening Test – The screening test involves making a number of 50 mm diameter drill holes where a “core”
is taken from the external walls, samples of foundations and, where accessible, internal walls and the chimney.
The examination will identify that the concrete is made up of suitable materials and hence Class A.
In some cases, after the Preliminary Stage 1 when concrete cannot be placed into ‘A’ or ‘C’, it is recommended that further testing is carried out.
Stage 2
The stage 2 examination will identify and classify results that cannot be defined by the above test and determine Class ‘B’.
Stage 3
The stage 3 examination will assess the performance of the aggregate material with the core samples previously taken.
It can be applied to ‘Class B’ material following the stage two investigation when, in the opinion of the surveyor and
the petrographer, they are satisfied that the property’s structural condition and examined core material do not indicate
visible deterioration.
Tests are carried out in laboratory conditions to simulate extreme weathering.

Currently:
•Class A1 – A3 are mortgageable (subject to lender)
•Class B and C are unmortgageable

Take a look at these resources to get more information on Mundic Block Testing, the different classifications and the cost:https://cornwallconsultants.com/mundic-tests/https://wheal-jane-consultancy.co.uk/building-services/