We are cleaning all the underground duct work in the slab home which is transite pipe with metal fittings, the weak rusted fittings are allowing the sand backfill to enter the duct and blow up into the home, so after we clean we are applying our trenchless cast mortar to all metal fittings to restructure the fitting and also applying two applications of our duct lining material to the entire underground duct work system leaving a nice clean air flow up into the home!