Replacing baseplates on sleeper walls and joists

[Ran Kamature]

After having a rising damp problem fixed with a chemical DPC I now have to replace the joists and baseplates which were damaged (problem exacerbated by lack of ventilation from installing Laminate flooring and vapour barrier over floorboards). The sleeper walls are still damp and appear to have no DPC. Can I install one under the new baseplates and do I lay mortar/DPC membrane/mortar/baseplate, or is it simpler than that?