Order a Mundic Block Test

PASS – MORTGAGEABLE

Class A1 means that no mundic block has been found in the concrete; it is not affected now, nor can it become affected in the future*.

This is determined by a normal STAGE1 screening test, the most common test undertaken and always the starting point. About 80% of Stage1 tests achieve Class A1.

*Although Class A1 samples cannot change, samples are only taken at certain points. Mundic can occur in a property Classed A1, if a mixture of concrete was used and no sample of the affected area was taken. It is the role of the surveyor to design a representative sampling regime in accordance with the RICS guidance.

PASS – MORTGEAGABLE

Class A2 means that the concrete contains some mundic but not a large proportion and there is no sign of degradation.

This is defined by a STAGE 2 test (either petrographic; dry density or chemical). Stage 2 tests are undertaken if samples have been defined as UNCLASSIFIED from Stage 1.

PASS – MORTGAGEABLE*

Class A3 means that the concrete contains a greater proportion of mundic than Class A2 but it has been shown that it is unlikely to suffer adverse effects in the future.

This is determined by Stage 3 testing, which involves exposing samples to accelerated weathering to see how the concrete will hold up in the future. Stage 3 testing is an option for samples found to be Class B, but Stage 3 testing is very expensive and in some cases can take up to a year to complete. It is not appropriate in all circumstances.

*Clients should check the acceptability to lenders of the possible outcomes before instructing Stage 3 testing.

FAIL – UNMORTGAGEABLE

Class B means that mundic has been found to make up more than 30% of the concrete. No assurances for the future of the concrete can be provided at this stage even if it appears sound.

This is determined by a Stage 2 test. Whilst it is possible in some cases to undertake Stage 3 testing to try to achieve Class A3, this is not always appropriate. If found to be localised within a building, Class B concrete can sometimes be physically removed and replaced.

FAIL – UNMORTGAGEABLE

Class C1 means that the concrete contains mundic and this is already attacking the cement, weakening the concrete. These samples are considered ‘unsound’ meaning they are fractured, broken, voided, or crumbly.

This is determined from either Stage 1 or 2 testing. If found to be localised within a building, Class C1 concrete can sometimes be physically removed and replaced.

FAIL – UNMORTGAGEABLE

Class C2 means that the concrete does not actually contain large proportions of mundic, but it is weak, broken or crumbly (unsound) for another reason.

Class C2 is determined by Stage 1 or Stage 2 testing. If found to be localised within a building, Class C2 concrete can be due to a range of building issues (other concrete quality problems); water infiltration or attack from flue gasses in chimneys are typical. Class C2 concrete can sometimes be physically removed and replaced.

Needs further testing to determine mortgageability

‘Unclassified’ means that some mundic has been identified in the concrete but we can’t tell how much from the Stage 1 screening test.

This is determined by Stage 1 testing, but no specific classification can be assigned without doing more detailed testing by one of the Stage 2 methods. Many ‘unclassified’ concrete samples go on to pass at Stage 2 testing by achieving a Class A2 classification. Some will pass at Stage 3 to achieve Class A3. Some will fail and achieve Class B.