hi all.im a plasterer,who has done very little damproofing,virtually none,lol.friend asked me to do a bit of work for her,as shes just bought a small house to rent out.its quite clear it has a rising damp problem,i plan on using dryzone cream to the affected areas,theres about 25 metres in total,the mortar bed on the walls when ive taken the old render off, not to bad for injecting the cream,however i was also thinking of tanking the wall a metre high also as a backup,am i being extreme?i just dont want her to come back to me with any problems.also am i better off using a render with waterproofer mixed in,then just skim as normal,or better of using something like renderlite, or dricoat or a lightweight backing plaster instead of render,thanks guys for any advice offered.