Fact: all the above solutions can only manage rising damp short to medium term. For a full, long-term solution a damp proof course must be part of the solution package - this does not have to be a chemical DPC but any working alternative.
Here is the technical explanation why is this.
The study of rising damp involves four dynamically interacting key areas:
- The soil
- The wall fabric
- The finish
- The environment (air)
Every solution on the marketplace that attempts to solve rising damp, deals with one or more of these four areas. The most common rising damp solutions [with the areas they address] are:
- Drainage [soil]
- Damp proof course (DPC) [wall]
- Wall-base ventilation [wall]
- Wall rebuilding [wall]
- Replastering [finish]
- Heating [environment]
- Room ventilation [environment]
Each and every one of these solutions has SOME effect on rising damp, but the efficiency and longevity of these solutions varies widely.
The ideal solution to rising damp would be the one that would solve it permanently. You do it once and then it's done You don't have to ever do it again (or at least not again in a lifetime).
Of the above list, damp proof courses are the only one that have the POTENTIAL to fully solve rising damp long term by blocking the upward movement of water and salts from the ground. Now, whether the various DPC technologies on the marketplace today live up to the promise of solving the problem of rising damp for a lifetime, that's an entirely different matter. But some of them have the potential of fully barring the water from the walls.
Any other solution NOT solving the problem at the wall level, but doing something else AROUND the wall - addressing the soil, the finish (the wall surface) or the environment - don't even have the POTENTIAL of solving rising damp permanently because they don't block the water off the wall, which just keeps rising.
These solutions, although beneficial, at best they can only "manage" the problem of rising damp by reducing its severity or by covering up its symptoms - giving building owners a few years break before the problem reappears and needs attention again.
Apparent Workability of the Secondary Solutions
These secondary solutions work better newer buildings, when the building fabric is not so loaded with ground salts. The older and saltier the building fabric, the damper the wall gets and the less efficient the drainage - replastering - heating & ventilation combo will become.