DAMP PROOFING HELP & ADVICE
Rising damp is a very common problem in old houses due to the fact that most old buildings were built without damp proof courses. Rising damp is caused by the upward flow of moisture from the ground through the capillaries in the wall. We have a range of products to help including damp-proof courses, render additives and damp proof membranes.
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:
Spoiling of internal finishes
Erosion of the building fabric
Reducing the thermal properties of the structure
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 that is used.
Whilst other factors will also impact the potential height of rising damp, in reality this height is moderated by the fact that the water will eventually evaporate unless there are other factors in play that might inhibit evaporation. As a result, in most cases it is rare to see rising damp exceeding 1.5 metres above ground level.
What about hygroscopic salts?
Rising damp is inextricably linked to hygroscopic damp – that is, the rising water also transports moisture-attracting (hygroscopic) salts that are left behind within the fabric of the walls when the water evaporates. As a result, even if the water source of a rising damp problem is resolved, an internal damp problem may still occur due to the hygroscopic salts attracting moisture from the air inside the building.
These salts can also damage internal plaster when they expand inside the pores of the substrate during the process of crystallisation. It is therefore often necessary to replace plaster that has been damaged in such a way, whilst also aiming to avoid future problems that might be caused by the hygroscopic salts.
How do you stop rising damp?
Once a detailed survey has accurately identified rising damp in a building, the best method for stopping it is a two-part process. Thanks to our 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 moisture at its source
In any new-build situation, to prevent rising damp from progressing upwards through a wall, a physical barrier to the rising water is inserted in the form of a damp proof course (DPC), such as the BBA certified Newton 809-DPC. However, installing a new physical DPC into an existing structure is prohibitively expensive and impractical in most situations. An alternative solution is therefore required.
The most practical and cost-effective method is therefore to use Newton 804-DPC to convert an existing mortar course within the wall 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.
3D image showing Newton 804-DPC injected into the mortar course of an existing brick wall suffering from rising damp
2. Reinstating damaged or salt-contaminated plaster
Although the new DPC is almost immediately effective, hygroscopic salts still residing within the wall fabric will still attract moisture, and will still cause the wall to be damp. Correct re-plastering is therefore essential, and in such scenarios Newton 808-RA can be employed as a salt-resistant render additive, and an essential part of the Newtonite 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 use different products in combination 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 Proofing membranes can be used together with Newton 804-DPC where the wait time for the wall to dry out is not practical, or as an alternative to direct rendering with Newton 808-RA render. Newton also recognise that in some situations it will not always be possible, practical or recommended to inject a new DPC and a wall membrane – like Newton 805 Newlath - will be the only solution in many circumstances.
Newton 805 Newlath has a meshed surface which creates a mechanical key to allow the membrane to be plastered, rendered or to receive dot & dab plasterboard