If asbestos is in sound condition and a risk assessment has determined that it is unlikely to be damaged then you may decide that the asbestos be encapsulated and managed instead of removing it. NIC offer a specialist encapsulation service.
Several aspects must be considering before making this decision and here at NIC we will help you determine the most appropriate course of action for your particular asbestos issue. Please contact us for free advice.
The condition of the existing asbestos application is of prime importance, particularly sprayed asbestos, because encapsulation should only be considered if the asbestos is in sound condition and adhering firmly to the substrate. Of equal importance, is the need to ensure that there is not likelihood of water penetration into the asbestos from the substrate after encapsulation, or the additional weight of absorbed and trapped water will cause the asbestos to delaminate.
Possible future damage to the application must be taken into account, e.g. from structural movement, vandalism, tools and equipment or vehicles such as fork-lift trucks and the need for future maintenance work.
Since encapsulation with selected products, should maintain the attributes of the original asbestos application e.g. fire resistance, acoustic or thermal insulation, it will avoid the need to replace asbestos with an alternative material and with the consequential costs involved.
The type of asbestos application and the ease of accessibility must also be considered before deciding on this course of action.
It should be noted that if encapsulation is the desired option then the asbestos will need to be appropriately managed, i.e. inspected at regular intervals, fully labelled and all relevant personnel and contractors made aware of its presence.
If the condition of the asbestos is satisfactory the encapsulation works will normally be carried out without the provision of an enclosure. However, the risk assessment and POW would determine the need for an enclosure.
Initial preparation may include the need to repair minor damaged areas especially where required fire resistance has been compromised.
Dependent on the surface condition of the asbestos, a light coat of a PVA solution should be applied at a lower pressure than the final applications. This is to consolidate the surface prior to the application of one of more coats required to achieve manufacturer’s recommended thickness of the dried film encapsulant.
The final coats of this type of encapsulant may be reinforced with non-asbestos fibres, dramatically increasing the resistance to impact. The open mesh scrim reinforcement should be applied to the wet surface between final coats. A glass fibre scrim is recognised as giving greater reinforcement than calico.
Where sprayed asbestos applied to structural beams and columns cannot be coated on all surfaces, small gaps should be bridged with a fire-resistant material and the encapsulant should be applied beyond the asbestos application, to ensure integrity of the encapsulation process.
On large encapsulation projects the encapsulants will be applied using an airless spray machine. However, on small jobs brush applied layers will be deemed sufficient – the POW will determine the most suitable application process.
