Solving rising damp requires very exact, specific steps. Let's recap first what the problem is, what we are trying to solve.
Rising damp is the natural upward movement of water inside porous masonry.
Rising damp is a STANDALONE phenomenon that can occur on its own on both internal or external walls, even in well-maintained buildings, independent of any other dampness problems or building defects.
Rising damp is NOT CAUSED by various building defects or lack of proper maintenance (such as a bridged damp proof course, the use of cement plasters, non-breathable materials, improper pointing, higher ground levels, lack of heating etc.) – although such problems, by creating their own set of dampness issues, interfere with the dynamics of rising damp, often “amplifying” its symptoms, making it worse or bringing it into view.
Fixing any of these defects, if they exist, will improve the building; but rising damp - if unaddressed on its own - stays there and will create problems (years) later.
A very important but often less known or neglected aspect of rising damp are ground salts. The rising water flow draws up diluted salts from the ground, depositing them into the building fabric. Following the evaporation of water, salts crystallize, expanding 5-10 times in volume. The exerted mechanical expansion pressure (crystallization pressure) leads to the cracking, crumbling and flaking of the plaster and wall fabric – a combination of symptoms commonly known as rising damp.
Crystallizing salts are the primary cause behind crumbling and the gradual, slow decay of masonry. Because over decades or centuries salts become a permanent part of the building fabric, their presence must be known and “managed” by using appropriate renovation materials.
The Correct Solution for Solving Rising Damp
Solving rising damp is a very specific technology, requiring very specific, exact steps. If done correctly by experienced professionals who understand the underlying mechanism of rising damp, and know what they are doing, solving it is not guesswork, nor trial and error, but a precision technology.
Because rising damp is a dual, combined problem of water and salts, a permanent solution to the problem MUST address and solve the following two technical aspects:
- Stop the rising water: to allow the wall fabric to dry and recover.
- Deal with the salts: in order to ensure a long-lasting finish, the new plaster MUST be protected from the destructive effect of salts, by separating it from the underlying salt-laden wall fabric.
These steps are achieved by the following actions:
Step 1 - Installing a DPC
Installing a damp proof course (DPC) is necessary to prevent the rise of water and further accumulation of salts. Several DPC technologies exist on the market, including non-invasive magnetic DPCs.
Step 2 - Renovations
To make the salt damages good and to ensure a good looking finish, a certain amount of renovation is usually needed. Several correct renovation options are available, giving you choices. Many incorrect solution are also present; we are going to cover these as well, so you can recognize and avoid them.
There is NO OTHER solution. There are no shortcuts. Doing anything less than BOTH the above two steps, it is not a full solution, which will result in the future reoccurrence of the rising damp problem.
Let's look at both of these steps now in more detail.