Where mastic asphalt tanking is to be repaired or joined to previously laid material making it necessary to cut into existing asphalt, the work must be carried out be a specialist mastic asphalt contractor.
When removing an area of asphalt, the lines of the cuts should be covered with molten asphalt until the underlying material has softened. The asphalt should not be removed until this has taken place. Under no circumstances should a hammer and chisel be used to cut cold asphalt. An angle grinder may, however, be used as an alternative.
The cut edge of the existing asphalt should be softened using molten asphalt and removed to two thirds of its depth for a width of approximately 75mm and to a third of its depth for a further width of approximately 75mm and to a third of its depth for a further width of approximately 75mm. A three layer lapped joint can then be formed between the new and existing asphalt.