What is Sarking?
Sarking felt is an underlay that is positioned beneath the tiles of a roof to provide a secondary defence against windblown rain. It is often a bituminous product although now many new modern varieties exit and these do not contain asbestos.
Does sarking felt contain asbestos and is it dangerous?
Yes, asbestos was used in bitumen. Although the level of asbestos in bitumen is minimal, it is always advised to employ a specialist to conduct an asbestos survey and organise the removal safely and in accordance to legislation.
Bitumen coatings (used up to1999) usually contain up to 8% chrysotile asbestos. Other materials that contain bitumen including asbestos floor tiles and adhesive and roof coverings are unlikely to release fibre under normal conditions, but asbestos fibres might be released when the material is cut or disturbed. Old bitumen can become brittle and powdery, if it contains asbestos, it will be very dangerous if the dust is inhaled. An asbestos survey will reveal if the bitumen contains asbestos.
When did they use asbestos containing bitumen roof sarking?
Bitumen roof sarking has been used since the 1920 ’s up to modern day. However, asbestos containing sarking was used from the 1920 ’s with brands such as ferval. Asbestos con be identified in any property potentially all the way up to 1999when asbestos was banned. Its still possible to find asbestos in bitumen in properties that were constructed pre 1999 that may not have been updated and renovated over the years.
What other bituminous materials can contain asbestos?
Bitumen is a black, tacky and hardwearing. It was commonly used in many buildings constructed before 2000 and the materials can be easy to identify. Materials in older properties may contain asbestos and its worth getting them tested or asbestos survey to identify the quantities of materials present. Materials such as the below list can contain asbestos,
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- Adhesive to asbestos floor tiles
- Adhesive to parquet floorings
- Bituminous seals and mastics
- Asbestos roofing felt was often used for garage roofs, outbuildings etc.
- Gutter liners
- Flashings
- Bitumen damp-proof courses (DPC).
- Asbestos bitumen coatings on metals
In conclusion
Our experiences with sarking felt are that yes, there are certain felts that contain asbestos. With years of surveying/sampling and carrying out the analysis of our samples we have managed to recognise sarking felts that are worth sampling. Although a very high percentage of these come back as negative it is worth getting enough evidence first to decide which types of felt you are going to sample. If in doubt we will sample it.
Many organisations do sample roof sarking felt during surveys but not all. Whilst some samples produce positive results this does not seem to be ‘the norm’ with the majority of samples returning negative results. However as with all asbestos containing materials caution is advised.
How can Summit Environmental help you?
Asbestos testing of sarking felts
Asbestos testing of bituminous products such as roof felts and floor tiles adhesive
Asbestos management surveys
Asbestos refurbishment surveys
