As with cellars and tanking, most contractors use the Hey’di K11 Grey Tanking System and generally do not carry out chemical injections as experience has shown that this is generally less effective. Internal plaster surfaces are cut to a height of 1.2 metres above floor level, the masonry surfaces are treated before applying a render to certain specifications, and then the Hey’di K11 Grey treatment is applied. This is finished with a coat of renovating plaster and then a coat of multi finish and left ready for redecoration. Some contractors may also include replacement skirting boards and door architraves where necessary within their quotes. These damp-proofing works usually carry a thirty year guarantee.