Asbestos surveys

Rules for Type 3 asbestos surveys - for agreeing the scope of the survey, etc.

NOTE: MDHS 100 has been superseded by Asbestos: The survey guide. The text below is for historical information only.

In his role as an expert witness, Paul Winstone, (the current chair of the RICS Asbestos Group and the author of this Asbestos section on isurv), is often involved in disputes where the main issue concerns the accuracy or thoroughness of asbestos surveys, in particular, for Type 3 asbestos surveys.

Based on his experience, he has set out below a summary of the issues and gives advice on how some of the problems, which frequently arise, can be overcome.

The background

MDHS (method of determining hazardous substances) 100 Surveying, sampling and assessment of asbestos-containing materials produced by the Health and Safety Laboratory, published in 2001, describes 3 types of asbestos survey:

  • 'Type 1 Location and assessment survey (presumptive survey)';
  • 'Type 2 Standard sampling, identification and assessment survey (sampling survey)'; and
  • 'Type 3 Full Access sampling and identification survey (pre-demolition/major refurbishment surveys)'.

The purpose is the same for all 3 types of survey, namely 'to locate as far as reasonably practicable, the presence and extent of any suspect ACMs' (asbestos-containing materials).

The important distinction between them is the scope of investigation that is required.

The Type 1 survey is based purely on a visual inspection, both of the materials in situ and by reference to any drawings and/or specifications that are available, e.g. by reference to the Health and Safety File or other as-built record information. Any materials other than those, which by virtue of their appearance or nature are known not to contain asbestos, e.g. wood, concrete, plastic or metal, or which were installed after the use of the relevant form of asbestos was prohibited, might therefore reasonably contain asbestos and must be deemed to be ACMs until proven otherwise.

The Type 2 survey is similar, except that the materials suspected of containing asbestos are sampled and tested to prove or disprove the supposition.

The inspections involved in both the Type 1 and Type 2 surveys are limited to those areas that are defined by the client's brief and which are reasonably accessible at the time.

The Type 2 survey is further limited by the restrictions imposed on sampling by the need to minimise the damage of the building fabric and finishes and of the disturbance of the building occupants. It is appropriate for assessing risks for the management of asbestos in occupied premises but any areas that are inaccessible, for whatever reason, must be presumed to contain asbestos and managed as such, until proven otherwise.

The Type 3 survey is not intended to have any restrictions as it is required to be carried out prior to building works or alterations that might inadvertently disturb asbestos containing materials, including not only those which are evident but also those that might reasonably be concealed within ducts, in voids above ceilings, below floors or behind wall linings or built into the fabric of the building or the services installations.

Paragraph 15 of MDHS 100 which describes the Type 3 survey, states that this type of 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 may be difficult to reach'.

The principle of the Type 3 survey is, to identify all asbestos materials, as far as is reasonably practicable, prior to any building works commencing, in order to avoid exposing workers, or other persons affected by their works, to respirable asbestos fibres, without adequate control measures being in place.

The 3 different types of survey are not mutually exclusive and are sometimes used in conjunction with each other for the inspection of separate parts of the same building or structure.

Problems can arise, either due to the lack of understanding, or unrealistic expectations, of the client or from the misinterpretation of the client's requirements by the asbestos inspector.

It is imperative that anyone commissioning an asbestos survey is made aware of the different types of survey, their different purposes and their limitations. The asbestos inspector must know the reason for the survey and has the responsibility for ensuring that the client understands the implications and any significant restrictions of their brief.

The solution is involvement by the client, or the client's advisor, in the development of the brief for the asbestos survey, and clarification and confirmation of the scope of inspection and sampling (where appropriate).

Suggested rules for the brief for a Type 3 asbestos survey

No

Rule

Comment/action by surveyor

1

A Type 3 survey is only appropriate when the whole or part of the premises is due to be demolished or refurbished.

Any other situation is only a Type 2 survey, with the risk of subsequently finding additional ACMs.

2

The property or relevant part should be vacant to allow full access for intrusive investigation.

If not, the client must be informed if this significantly limits the survey.

3

The scope of any proposed building works should be known to all parties, so that the extent of the areas which will be disturbed can be accurately defined, e.g. above and below ground, interconnecting or adjacent areas or services, etc.

This must be made absolutely clear in the confirmation of the brief.

4

Special arrangements are required in listed buildings, e.g. replacing cables or other services where the disturbance of the building fabric must be minimal.

These might include carrying out the investigation in phases (see No 8 below); some parts may not be investigated in which case they must be presumed to contain ACMs until proven otherwise.

5

The strategy of the survey must be understood and agreed by all parties. (Are all ducts, beam claddings, floor and ceiling spaces to be inspected and every part of each, or is it reasonable to presume identical and repetitive construction and thus only make representative sample inspections?)

 The client must be a party to and agree the strategy, appreciating and sharing the risk involved.

6

The scope of the opening up and the clearing up must be agreed, e.g. is temporary making good required?

This must be absolutely clear in the confirmation of the brief.

7

The implications of the disturbance of adjacent areas in connection with the investigations, or the subsequent discovery of additional ACMs must be known and appreciated by the surveyor, e.g. if client needs to provide essential non-stop 24-hour services.

This must be noted in the confirmation of the brief and reflected in the agreed survey strategy.

8

If it is not feasible to carry out the investigation in a single phase, the sequence and programme must be agreed and recorded (e.g. returning to site when the contractor has reached a particular stage to carry out further investigation).

This must be absolutely clear in the confirmation of the brief or subsequently in the report to client.

9

When there is the risk of finding additional ACMs during the demolition or refurbishment, then this must be conveyed to the contractor (it is not sufficient to presume that all materials will be treated as 'suspect').

Checks should be carried out to ensure that the contractor's workers have received appropriate 'asbestos awareness' training, that terminology used in reports is clear, and that any known ACMs and all areas that have not been inspected are clearly identified. Descriptions should be reinforced by the use of marked up drawings where possible.

10

Where other types of asbestos survey (Types 1 and/or 2) are carried out concurrently in the same building or structure and are included in a single report.

 Avoid misleading and unofficial terms such as 'Partial Type 3 survey'.