I have a long retaining wall which will form the back of a new building. I am thinking of tanking it with vandex BB75. Its a cotswold stone wall and very rough surface. I have filled all the worst crevises and holes as advised by the Vandex data sheet. Has anyone experience of this product and can anyone reccomend the best method of application please? The surface is far too uneven to trowel and brushing sounds like it could take for ever. It will eventually be dry-lined with 4x2 as stipulated by the BCO