Surveys to MDHS 100

MDHS 100 refers to the Methods for the Determination of Hazardous Substances, Health and Safety Laboratory publication number 100, which is entitled 'Surveying, sampling and assessment of asbestos-containing materials' (ACMs).

MDHS 100 is the industry standard for the provision of asbestos surveys and details three types of Survey:
Type 1: Location and assessment survey (presumptive survey)
Type 2: Standard sampling, identification and assessment survey (sampling survey)
Type 3: Full access sampling and identification survey (pre-demolition/major refurbishment survey)

All asbestos surveys must do three things:

• Locate and record the locations, extent and product type of any presumed or known ACMs, as far as is reasonably practicable
• Inspect and record information on the accessibility, condition and surface treatment of any presumed or known ACMs
• Determine and record the asbestos type, either by sampling and analysis or by making presumptions based on product type and appearance, etc.

The collected information must be held in a suitable (upgradeable) form and should be accessible to, and understandable by, all relevant personnel. This is usually achieved in the form of a register, which contains an algorithm called the Material Assessment.

The type of Asbestos Survey you require depends very much on your Asbestos Management plan and what you intend to do with the building.

Type 1

A Type 1 survey is effectively a walk-through survey and does not involve the sampling of ACMs or suspect ACMs for analysis for the presence of asbestos. For this reason, the Type 1 survey can be relatively quick and cheap, in the short term.

In a Type 1 survey, any material which can reasonably be expected to contain asbestos must be presumed to contain asbestos, and where it appears highly likely to contain asbestos, there should be a strong presumption that it does. All materials which are presumed to contain asbestos must be assessed.

Given that there are in excess of 3,000 ACMs, a Type 1 survey leads to a large and unwieldy resister. In addition to this, no item on your asbestos register that is listed as 'Presumed' or 'Strongly Presumed' to contain asbestos may be worked on until a sample has been analysed by a UKAS accredited Laboratory.

The result of a Type 1 survey is that every time any sort of tradesman needs to carry out any sort of work that might disturb one of your 'Presumed' or 'Strongly Presumed' suspect ACMs, a sample must be taken and analysed and the Asbestos Survey and register must be updated. The ongoing costs, both financial and in terms of time and delay, can quickly offset any savings made during the original survey.

Type 2

A Type 2 survey uses the same principle as a Type 1 survey, except that the surveyor samples the materials that are 'Presumed' or 'Strongly Presumed' to contain asbestos, for bulk sample analysis.

If the material sampled is found to contain asbestos, other similar homogeneous materials used in the same way in the building can be 'Strongly Presumed' to contain asbestos.

The Survey report and Register of a Type 2 Survey will, in the Material Assessment, state the product type of the material and the type of asbestos contained within. In this way you will be able to tell whether the material is an Asbestos Cement, containing white asbestos or Asbestos Insulating Board, containing brown asbestos, and take the appropriate actions.

The Type 2 survey, although more time consuming and expensive at the time, is by far the most common type of MDHS 100 Survey carried out throughout the nation.

Type 3

A Type 3 survey is used to locate and describe, as far as reasonably practicable, all ACMs in the building and may involve destructive inspection, as necessary, to gain access to all areas, including those that are difficult to reach.

A full sampling programme is used to identify possible ACMs and estimates of the volume and surface area of the ACMs are made.

The survey is designed to be used as a basis for tendering the removal of ACMs from the building prior to demolition or major refurbishment, so the survey does not assess the condition of the asbestos, other than to note areas of damage or where additional asbestos debris may be expected.

The important thing to remember with a Type 3 survey is that it is destructive in nature. Cavity walls, floors and ceilings must all be accessed, which will involve, making holes in the non-asbestos materials forming the cavity. People with listed buildings should be particularly careful when asking for a Type 3 survey and ensure that all requirements are fully documented.

Receiving the Asbestos Survey, regardless of which type it is, marks the beginning of the Duty to Manage, not the end of it. Now that all the ACMs and suspect ACMs have been identified, you are able to start managing them, see the Asbestos Management page for further information.

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