Treating Rising Damp
Having to deal with rising damp is stressful for homeowners.
Once they have found the problem, they have to search for a reputable surveyor and contractor to come and remedy the problem.
They then have to deal with the expense and disruption of the actual rising damp treatment works being carried out before they can even think about redecorating and returning their property to normal.
The most common method for treating rising damp is to remove salt-contaminated plaster and then inject a silicone damp-proofing cream at regular intervals into holes drilled along a horizontal mortar course on the affected wall. On a successful treatment, the active silicone ingredient contained within the cream will spread through the mortar course and cure to form a waterproof barrier to damp. The wall is then replastered using a salt-resistant plaster or render.
The most common point of failure with this treatment method is the damp-proofing cream.
If a damp-proofing cream with an insufficient amount of silicone active ingredient is used or an insufficient amount of cream has been injected, this waterproof barrier will not properly form and the damp will not be halted.
There is a considerable disparity among various damp-proofing creams, as not all are created equal. An effective, high-strength damp-proofing cream, such as Dryzone Damp-Proofing Cream, typically comprises a minimum of 60% active ingredients, creating a durable barrier against rising damp. In contrast, some creams available in the market contain significantly lower levels of active ingredients, often falling below 15%.
In laboratory assessments that compared these low-strength creams to Dryzone Damp-Proofing Cream.
It became evident that the former lacked the capacity to diffuse adequately, rendering them ineffective in combating rising damp. This ineffectiveness occurred despite the fact that both the low-strength and high-strength creams possessed the same UK certification, highlighting the critical distinction in performance between different damp-proofing products.
Even if the correct materials are used, the rising damp treatment can still fail due to operator error. Often, when a high-strength damp-proofing treatment has failed, it is because the installation operative has not fully filled the injection hole with cream. It can also be the case that a void or fissure in the injection hole has caused the cream to be directed away from the treatment location. In both cases, the waterproof barrier will not properly form due to an inadequate amount of active ingredient being delivered.
Another variable that can further exacerbate a failed damp-proofing cream treatment is the choice of material used for replastering. The height of rising damp is determined by both the porosity of the building materials and the rate of evaporation. If a very dense and non-vapour permeable material, like sand and cement render, is used to replaster over a failed rising damp treatment then it can actually push the height of the damp higher than its original height, causing further damage.
To ensure this does not occur, it is highly recommended to
use a breathable salt and damp-proof renovation plaster, such as Dryzone Damp-Resistant Plaster. This means that, if a failure of the damp-proofing cream was to occur, the rising damp would not rise any higher than it originally did.
The best way to avoid treatment failure is to use Dryrod Damp-Proofing Rods. These patented fibre rods are directly impregnated with the correct amount of active ingredient to treat rising damp. Just like damp-proofing creams, they are inserted into holes drilled along a horizontal mortar course.
As Dryrod Damp-Proofing Rods are directly impregnated with the active ingredient, they represent the best available performance in the remedial damp-proof course category.
They also contain exactly the correct amount of active ingredient for their given length, ensuring the right amount of material is delivered and under-treatment is not a worry.
When a rising damp treatment has failed, it is necessary to install a second damp-proof course treatment. If you are using damp-proofing creams, this treatment must take place on a separate mortar line to the original. Even though the first treatment was unsuccessful, the drill holes will have cured to stop the spread of the cream.
If, however, Dryrod is used to carry out the retreatment, the original drill holes can be used. The chemical formulation of the active ingredient contained within the rods is able to diffuse throughout the previously treated mortar course.
This case study shows exactly how to spot and treat a failed rising damp treatment using Dryrod Damp-Proofing Rods and Dryzone Renovation Plaster. For those wanting to know more about how to reliably treat rising damp, you can read our full guide to rising damp and its control.
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