• A few words on rising damp?

    All humidity problems are a result of capillary action, i.e. the action of capillaries in materials, except of course for direct water ingress.
    Pay special attention to the way in which rising damp is announced to you by professionals!
    There are indeed several devices on the market, the most sold is a device that lets power pass between two electrodes. Water being a “good conductor”, the measurement is taken on the dial and gives a scale corresponding to the percentage of humidity contained in the walls. It should be noted that it is not only water that is a conductor, but also salts, which are very often present in masonry: phosphates, sulphates, chlorides, etc.
    So, electrode devices might not be suitable for obtaining convincing results in terms of humidity content. These devices work on the basis of a power passing between two electrodes. The wetter the medium, the higher the measurement. But it can also be misled by salts in a dry wall. Salts are conductive elements.
    The only approved system is the CM method (Carbide Method). This device is available at BEAL office on the basis of a prior reservation for technical explanation and a deposit.
    In some cases, chloride formation can be observed in houses along the roads, which receive water with de-icing salts or in houses in coastal marine areas.
    In addition, nitrates can be formed from organic decomposition (farms, old stables, etc.). Beware also of bricks and porous reused materials which may contain nitrates depending on their origin.
    Treatment against rising damp in this type of building is one of the first operations to be carried out to allow the walls to dry out more quickly, as the building is open to all winds.
    Crystallisation of salts is a common phenomenon and these salts have a tendency to grow in volume, causing detachment of the finish and even bursts in the materials themselves.
    All salts are hygroscopic and retain water. When treatments are carried out, which are effective in the injection zone, there may still be areas of masonry above the injection barrier containing salts, particularly nitrates. In case of high concentration, these salts can cause disorders (damp stains) in very specific places and this will no longer have anything to do with rising damp problems.
    The presence of these salts can also be a very influential factor in determining the actual source of humidity.
    After a rising damp treatment, water remaining in the walls must still be removed by evaporation. As salts are soluble, water acts as a “carrying agent” of the salts that remain on the surface when the water evaporates.
    There are other systems to overcome this problem, for example the MORTEX NO3 coating. For more information on this problem, please contact us. Manufacturing to order depending on the availability of raw materials.
    Walls contain capillaries and have a surface tension specific to the materials present. The role of a good injection product is to leave a very high vapour permeability, but to prevent water from migrating through the capillaries. This barrier is achieved by changing the different surface tensions of the materials. Water will no longer rise through the capillaries and will be blocked at the point where the treatment has been carried out.
    CAPILASIL® fulfils this function perfectly.
    When injected in accordance with the professional standards and the installation instructions, it will give full satisfaction. The formulation is based on oligomeric siloxanes (10% of active ingredients). This means that they are very small molecules that will only block a few pores, which is a very important characteristic.
    Monomer-based silanes have even smaller molecules, but they are very volatile, so in order to have a concentration of around 10% of active materials on and in the walls, a product based on 30 to 40% of silane active materials would be needed. Polymers have a nasty tendency to block the pores because they have large molecules. They therefore block the pores and capillaries, greatly impeding vapour permeability.
    Important: Salts, and in particular nitrates, can form a chain that allows humidity to continue to rise after a conventional treatment.
    In order to avoid this major inconvenience, we propose a treatment with CAPILASIL HS (solvent phase) when the nitrate level exceeds 3.5 – 4%.
    In order to carry out this measurement, please send us by post or bring us at least 10 g of wall dust (most humid and porous areas). This wall dust being taken every 6 metres of the same wall at the level of the future injection barrier. Ask for our conditions.
    We will send you the results after analysis.
    It should be noted that in some cases, the walls are thought to be affected by rising damp when it is simply a matter of capillary action of the joint or a lack of material between the skirting board and the tiles. This allows then cleaning water (or accidental damage from a liquid spilt on the floor) to penetrate through the solid or hollow joint up to the plastering, causing rising damp. This phenomenon is more significant if the last tile laid against the wall slopes slightly towards the wall. As the plastering is not very porous and the skirting board is watertight, water storage becomes more and more important with each cleaning and can cause damage similar to walls affected by the same phenomenon. In this case, a simple silicone sealant such as MS polymer can solve the problem. After placing the sealant, allow the wet materials to dry thoroughly before repainting.
    If you would like to know more about rising damp injection products, please visit www.capilasil.com