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Decramastic Roofing May Contain Asbestos (ACM)



Some versions of mastic or bitumen based Pressed Metal Roof Tiles produced prior to the early 1980s contain asbestos.
Mastic or bitumen was the most common material used to adhere the stone chip to the pressed metal at that time.

All mastic or bitumen based Pressed Metal Roof Tiles should be suspected of containing asbestos until proven otherwise. Particular profiles which are likely to be affected include decramastic and early harveytiles, however other profiles may be affected.

Pressed Metal Roof Tiles manufactured by other parties are believed to have been introduced and manufactured after the ban on asbestos was implemented, but the same care should be taken regardless for any Pressed Metal Roof Tiles which may contain a mastic or bitumen based product.

The presence of asbestos can only be confirmed through sampling and testing by an accredited laboratory in accordance with the Health and Safety at Work (Asbestos) Regulations 2016 and the Approved Code of Practice: Management and Removal of Asbestos. A specialist company such as Hazmat should be engaged to undertake sampling, testing and remediation.

There are no risks associated with Pressed Metal Roof Tiles containing asbestos if they remain in good condition and are left undisturbed. A significant health risk arises when adhesive expires, stone chips become dislodged and asbestos fibres may become airborne and can be breathed into the lungs. This may occur if the tiles may be disturbed during maintenance, cleaning or removal.

Contact Hazmat for more information on 03 366-2262.

Decramastic-Roof suspect Asbestos (ACM)


    1. Hi there Wayne,
      for buildings once Asbestos has been found to be present in Mastic, an asbestos survey and management plan needs to be performed by a company certified by a BOHS IP402 for example like HazMat. If found to be in sound condition, then simply follow the management plan to the letter.

      The Management plan is a living document which ensures Staff / customers / Tradespeople / occupants (if a residential dwelling/ rental property) are safe. For more information about surveys or Management plans call HazMat directly.

      If the survey displays that it is deemed a high risk factor then the best course of action could be for immediate safe removal and reinstatement of another roof by a licensed Asbestos removalist like http://www.hazmat.co.nz.
      Any Licenced company performing a removal should be providing you with a third party assessor clearance certificate which shows the work has been done properly and is safe for re-occupation. For any further information please contact your Local Hazmat Expert

  1. Hi
    If my roof sample comes back positive for asbestos and I am advised to replace it, does the removal affect the insulation in the ceiling?

    1. Hi there Rebecca, depending on how the removal is done and whether or not sarking or building paper is underneath the roof and also if polythene or suchlike is laid to protect it during removal, it may be able to be saved. In reality, best practice and safety usually dictates replacement. Welcome to call us to discuss.

  2. Have just found out that my unit has tiles with asbestos in them.
    Can you please advise what my next step is? Who do I need to approach to remove these since my roofer says he cannot.

  3. Hi there,
    Roughly when did acrylic bonding glue replace the old mastic glue on these kind of pressed steel roofs?

    1. Hi there Dean, thanks for the enquiry, this is a tricky one and outside of our knowledge base.
      I suggest you contact Roofing Association of NZ (RANZ) here http://ranz.co.nz/ .

  4. Hi, wondering if you could advise whether decramastic tiles containing asbestos can be resurfaced/repaired once they have started to rust, or if they have to be replaced. Thanks.

    1. Hey There Kristy, Thanks for the enquiry.
      You did not mention if this was the entire roof that is now nearing this point or a few trouble areas. I will give you advise on both.
      Whole Roof:
      Like most materials, once compromised by rust or weathering, you need to recondition a substrate back so that it can be recoated / painted / remedied. Unfortunately when this material contains Asbestos, Worksafe does not recommend the usual methods of cleaning and preparing a surface for paint/glue/adhesives like scraping, waterblasting, sanding, grinding etc. Therefore I am yet to see a great example of what you can do to recondition an entire roof properly to give you longevity. Decramastic Tiles is one of the few products which does not take well to using encapsulants and membranes as it is gritty. Suggest A Reroof. CONTACT HazMat for a quote for this.

      In the case of point repairs, you may be able to remedy by replacing a line/row/tray using a qualified roofing company with appropriate PPE. I would not attempt this yourselves unless you know what you are doing, the way Decra is put down, it can be tricky. Hope that helps?

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