What is Rising Damp?
Simply defined, rising damp is the upward flow of moisture from the ground through the capillaries in a permeable wall structure.
Whilst numerous factors can affect its severity, such as wall thickness, groundwater levels, the type of masonry and the rate of evaporation, rising damp often requires treatment as it can have some extremely undesirable effects, including:
1. Spoiling of internal finishes
2. Erosion of the building fabric
3. Reducing the thermal properties of the structure
4. Negative health effects for occupants
What Causes Rising Damp?
Due to the phenomenon of ‘capillarity action’, water from the ground is absorbed upwards through the pores, or capillaries, within the walls. The potential height to which this moisture can rise is largely dictated by the type of material from which the walls are built, and in particular the type of mortar.
Whilst other factors will also impact the potential height, in reality this is moderated by the fact that the water will eventually evaporate unless there are other factors that might inhibit evaporation. In most cases it is therefore rare to see rising damp exceeding 1.5 metres above ground level.
What are Hygroscopic Salts?
Rising damp is inextricably linked to hygroscopic damp, as the rising water transports moisture-attracting (hygroscopic) salts that are left behind within the fabric of the walls when the water evaporates. As a result, even if a rising damp problem is resolved, an internal damp problem may still occur as the hygroscopic salts attract moisture from the air inside the building.
These salts can also damage internal plaster when they expand during the process of crystallisation, and it is often necessary to replace plaster that has been damaged in such a way.
How Do You Stop Rising Damp?
Once a detailed survey has identified rising damp in a building, the best method for stopping it is a two-part process. Thanks to their new BBA certified damp proofing products, Newton are able to provide clients with the complete rising damp solution for both parts of this process.
1. Stopping the rising damp
To prevent rising damp from occurring in new builds, a physical damp proof course (DPC), such as the BBA certified Newton 809-DPC is installed. However in remedial rising damp scenarios this process is often too expensive and impractical, and an alternative solution is required.
The best method is therefore to use Newton 804-DPC to convert an existing mortar course into a new DPC. Newton 804-DPC is a high strength damp proofing cream that works by diffusing into and along the mortar course before curing into a breathable and water-repellent barrier that stops the rising damp in its tracks.
2. Reinstating damaged plaster
Although the new chemical DPC is almost immediately effective, hygroscopic salts residing within the wall will still attract moisture, and will still cause the wall to be damp. Correct re-plastering is therefore essential, and Newton 808-RA can be employed as a salt-resistant render additive, and an essential part of the rising damp solution.
Used within the sand and cement render, Newton 808-RA will prevent the passage of both residual moisture and hygroscopic salts from the underlying masonry to the new decorative surface, ensuring that no further damage occurs.
What About Damp Proof Membranes?
Much like the best waterproofing solutions, the best damp proofing solutions combine different products to form the most comprehensive defence possible.
With the addition of these two new products, the Newtonite Damp Proofing System now contains a comprehensive range of products that can be utilised in different combinations dependent on the scenario. For example, Newton damp proof membranes can be used with Newton 804-DPC where the required time for the wall to dry out is impractical, or as an alternative to rendering with Newton 808-RA.
Newton also recognise that in some situations it will not always be possible, practical or recommended to inject a new DPC, and a damp proof membrane will be the only solution in many circumstances.
Collectively, the products within the Newtonite System make it possible to deal with all forms of damp, from rising damp to penetrating damp, residual hygroscopic damp and condensation, and always providing the client with a BBA certified solution.