1. Know what you’re dealing with
White asbestos, or asbestos cement, is the most common form found in UK roofs. The age and condition of the asbestos will determine the most appropriate approach to refurbishing the roof, so use a responsible organisation from design stage to advise on whether the required works will be classified as licensed, notifiable non-licensed or non-licensed works.
2. Consider the options
If stripping out the roof and replacement is ruled out, the options on refurbishing are patch repairs, over-cladding or encapsulation. Patch repairs may be feasible and relatively low-cost option but usually only provide a temporary fix, while costs associated with safe access for inspection, cleaning and repairing will be proportionally high.
3. Be careful with cladding
Over-cladding is an effective alternative to a complete strip out. But handling and drilling of the asbestos sheets involves greater risks of releasing asbestos fibre, and this option can be costly and time-consuming.
4. Encapsulation
Encapsulation stops leaks and prevents further degradation. There are various proprietary systems available, including Kemperol cold liquid-applied waterproof membrane system. Such systems add little weight, and can deal with penetrations, laps and gutters.
5. Good preparation is important
When specifying an encapsulation system, select one that will limit algae growth and remain flexible even at extreme temperatures. To ensure good adhesion of the coating, the asbestos roof sheets should be cleaned by a specialist contractor prior to installation to remove debris and organic material for controlled disposal.
By Mark Bruchez from waterproofing membrane specialist, Kemper System
