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Why you should test for mundic block if you are buying a property in the South West

Posted on January 24, 2018, by Maria Richards

Are you planning to buy a property in the South West that is more than 50 years old? Then there is a chance that your new home may contain mundic. Maria Richards from Coodes Solicitors’ Residential Property team explains why you may need a screening test.

What is mundic?

Mundic is a term used for blocks that are comprised of waste mining material mixed with aggregates, such as beach sand. The blocks were mass produced from 1900 to 1950, although in some areas the practice was carried out until the early 1960s.

The blocks were commonly used in property construction in South West England, primarily in Cornwall, as other materials were not always readily available during that era. Cost was also of primary concern at the time.

Why might I need to test for mundic block?

If you are looking to buy a property in the South West built between 1900 and 1965, your mortgage lender will, in all probability, require you to have an up-to-date test carried out for mundic block.

This is because some of the materials used in mundic block can cause deterioration and weakening, which in turn will cause subsidence to the property. This will have a major effect on the eventual decision to lend you money for mortgage.

Even if you are a cash buyer, and not planning to take out a mortgage, it may be a good idea to get this test completed to ensure that when it comes to selling the property on in the future, you will be able to do so at full market value.

How to test for mundic block

The test will help to analyse the category of materials used to construct the property. Drilled samples are taken from various parts of the building including the external walls, the foundation and the chimney, and are then examined by experts in a laboratory.

What do the results of my mundic test mean?

The results categories that your property could fall into are as follows:

  • Class A: Sound concrete. Satisfactory condition.
  • Class A/B: Concrete considered to be sound, subject to adequate protection and maintenance.
  • Class B: Concrete contains more than 30% of possible problem aggregates, although it appears sound, it could cause potential problems.
  • Class C: Those found to be clearly unsound from examination.

Most mortgage lenders will require either a Class A or Class A/B result to meet with lending criteria. It is often the case that properties don’t directly fall into Class A or C, but instead in the middle of the spectrum, which usually means more testing.

Only about 5% of properties fall into Class C, with around 80% of screening tests meeting Class A requirement. Only 15% of properties will show inconclusive results, needing further rounds of testing.

Having a mundic block test is a sensible step to assess the future prospects for selling your home.

For more advice, please contact Maria Richards in the Residential Property team at Coodes Solicitors on 01726 874752 or

You can also download this information as a pdf.


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